US2987047A - Fluid-pressure actuated control apparatus - Google Patents

Description

June 6, 1961 D. H. YOUNG 2,987,047

FLUID-PRESSURE ACTUATED CONTROL APPARATUS Filed Aug. 18, 1959 2 Sheets-Sheet 1 30 32 v Inventor Wm, 42 AM A ttorneys June 6, 1961 D. H. YOUNG 2,987,047

FLUID-PRESSURE ACTUATED CONTROL APPARATUS Filed Aug. 18, 1959 2 Sheets-Sheet 2 I, 4 v l 7 FIG. 2.

Inventor United States Fatent 2,987,047 FLUID-PRESSURE AC 'UATED CONTROL APPARATUS David Horace Young, 54 St. James Ave., Hampton Hill, Middlesex, England Filed Aug. 18, 1959,,Ser. No. 834,458 Claims priority, application Great Britain Sept. 9, 1958 9 Claims. (Cl. 12138) This invention relates to fluid-pressure actuatedcontrol apparatus. In its more important aspect the apparatus is adapted to dispense a lubricant or other substance at any desired controlled rate within limits. The apparatus of this invention is however not limited to this application but has numerous other applications: for example it may be utilized to actuate the blow-off valve of a steam boiler atpredetermined time intervals.

The fluid-pressure actuated control apparatus according to my invention comprises a chamber having a wall movable in one direction to decrease the volume of the chamber by fluid pressure acting directly or indirectly on-the wall, means for moving the wall inthe opposite-direction, a control member connected at one end tothe wall, a. reservoir for hydraulic fluid, a passageway connecting the reservoir withv the interior of the chamber, means for regulating flow of hydraulic fluid from the chamber to thereservoir when the wall is moved in said onedirection whereby to regulate movement of the control member, a fluid-pressure release means automatically actuated when the wall has moved in said one direction to a predetermined position whereby the fluid pressure on the wall is released and the wall is moved in said opposite direction, means for the passage of hydraulicrfluid from the reservoir to the interior of. the chamber when said wallmoves in said opposite direction, and means automatically actuated when the wall has moved in said opposite direction to a predetermined position to restore the fluid pres sure acting on the wall.

Apreferred form of fluid-pressure actuated control apparatus will now be described with reference to the accompanying drawings, in which:

FIGURE 1 is a central'vertical sectional view of-the apparatus;

FIGURE 2 is a partial view, similar to that of FIG- URE 1, showing the pistons and other parts in a different working position;

FIGURE 3 'is a top plan view of the apparatus;

FIGURE 4 is an enlarged sectional view of the valve means for regulating the flow of hydraulic fluid to the reservoir, and

FIGURE 5 is a view to an enlarged scale ofthe valve means controlling the escape of pressure fluid from the lower cylinder.

The apparatus shown in the drawings comprises two axially aligned cylinders 1, 2 separated by a transverse wall 3 provided with a through-hole which is axially alignedwith the cylinders and through which extends a piston rod 4 having at its ends pistons 5, 6 which work in the cylinders 1, 2 respectively. The cylinder 1 beneath the piston 5 receives pressure fluid, e.g. steam, from an inlet 7 and the steam passes from the cylinder through a passageway 8 controlled by valve means which are indicated generally by the reference numeral 9.

The space in cylinder 1 above piston 5 contains hydraulic fluid and this space is adapted to be placed in communication with a reservoir 10 surrounding the cylinder 2 by passageways 11 and 12: flow through such passageways is controlled by valve means indicated generally by the reference numeral 13. The space in cylinder 2 above piston 6 has an inlet 14 controlled by a nonreturn valve and an outlet 15 also controlled by a non return valve.

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The piston rod: 4has an axial bore extending upwardly from the lower end thereof and movable in this bore is a valve stem 16 having a collar 16" pinned to the upper end thereof. The lower end portion of the valve stem 16 has an integral, axially aligned valve 16 (FIGURE 5) comprising an intermediate reduced portion providing a head 17 and an annular shoulder 17' which is adapted to seal with the upper end of a flanged sleeve 18which is made for example of'polytetrafluo-roethylene and' which is retained in. the base of cylinder 1 by means of a screwed retainer ring 19; In all positions of the valve stem the valve head.17. seals with the inner wall of sleeve 18. The valve 16 has extending from the lower end thereof an axial bore 20 communicating with a plurality of radial passageways 21 and it will be seen from FIG- URES l and 5 that, with the valve 16' in the raised posi tion thereof shown in those figures pressure fluid entering the cylinder 1 will pass directly into outlet passageway 8 and thenceto the steam trap 22 via pipe 23.

A helical spring 24 surrounding piston rod 4 urges pis ton 5 to its lowermost position and a passageway 25 containinga spring-pressed ball 26in a part thereof of enlarged diameter extends between reservoir 10 and the space in cylinder 1 above piston 5. A substantially rectangular spring plate 27 secured at its ends to the base of cylinder 1 has two intermediately disposed longitudinally extending tongues having recessed ends which engage in an annular groove 28 in the valve stem 16 (see FIGURE 5) and this spring plate is adapted to snap the valve 16 from the lowered position shown in Figure 2 to the raised position shown in FIGURES l and 5 and vice versa. The spring 27 may advantageously be backed by a rectangular spring plate (not shown) secured at its ends to the base of cylinder 1 and engaging in the annular groove 29 on the valve stem 16 (see FIGURE 5).

The action of the apparatus so far described is as follows. With the pistons 5, 6 in the uppermost position thereof shown in FIGURE 1 pressure fluid entering cylinder 1 via inlet 7 passes freely to exhaust through radial passageways 21, bore 20, passageway 8 and pipe 23 and the piston Sand piston 6 are moved downwardly underthe action of spring 24. On downward movement of the pistons the lubricant or other substance to be dispensed is drawn into cylinder 2 via inlet 14 from a suitable source (not shown) and the hydraulic fluid is drawn from reservoir 10 through conduit 25 into the space in cylinder 1 above piston 5. Downward movement of the pistons continues until the end Wall of the axial bore in the piston rod 4 engages the upper end of valve stem 16. Further downward movement of the pistons causes spring 27 to snap past its dead centre position to the position shown in FIGURE 2 thereby causing valve shoulder 17 to move into engagement with its seat thus preventing escape of pressure fluid from cylinder 1. Pistons 5 and 6 then commence to move upwardly under the action of the pressure fluid, piston 5 forcing the hydraulic fluid through passageways 11 and 12 into reservoir 10, flow through passageway 25 being prevented by ball 26, and piston 6 forcing the substance to be dispensed through the outlet 15.

The rate at which the hydraulic fluid is forced into the reservoir 10 and thus the rate at which the substance is dispensed preferably comprises an elongated passage of gradually decreasing cross-section through which the hydraulic fluid is caused to flow whereby its pressure is reduced, and means for varying the cross-section of the outlet of the passage. In the construction illustrated the rate at which the hydraulic fluid is forced into the reservoir 10 and thus the rate at which the substance is dispensed is controlled by the valve means 13 which comprises a sleeve 30 (see FIGURE 4) which is screwed into a socket inthe wall 3'and whichistinternally thread: edat its innenend... The; valve means; l3calsocomprises' i 3 a stem 33 having a taper thread at its inner end which is screwed into the internally threaded portion at the inner end of the sleeve 30. The stem 30 is provided at its outer end with a handle 34 whereby the stem can be rotated and the axial position thereof varied.

The taper thread on the inner end of the stem 33 provides an elongated helical passage of gradually decreasing cross-section through which the hydraulic fluid is caused to flow in its passage from passageway 11 to passageway 12: the cross-section of the outlet of the passage may be varied by rotation of the handle 34. It will be appreciated that the hydraulic fluid in flowing between the threads of the sleeve 30 and the stem 33 has its pressure greatly reduced and this together with the fine con trol provided by the co-operating threads enable the rate at which the hydraulic fluid flows to the reservoir 10 to be very much more finely controlled than when a ball valve is used. The taper thread instead of being provided on the stem could be provided on the sleeve.

The thread may be of 8 mm. diameter and 0.75 mm. pitch and the taper on the thread may be from 0.315" to 0.303. The pistons in their ascent finally reach a position in which the annular lip 36 on piston engages collar 16" on the valve stem 16 and the valve stem is then raised so that the spring 27 snaps to the position thereof in which valve 16 is in its open position. The above cycle of operations is then repeated.

A pipe 37 (FIGURE 3) connecting passageway 12 with reservoir contains a sight glass 38 containing two spaced and axially aligned rods 39. In operative position of the apparatus the tube 37 extends vertically and the hydraulic fluid drips from the upper rod to the lower rod, thus enabling the rate at which the hydraulic fluid is forced into the reservoir 10, and thus the rate at which the substance is dispensed, to be readily judged.

The valve means 9 enable the direction of movement of the pistons to be very rapidly changed and it will be appreciated that the apparatus disclosed affords a simple means for closely regulating the rate at which a lubricant, a boiler water additive or other substance may be dispensed. Movement of the piston rod 4 may be utilized to control a wide variety of other operations, for example piston rod 4 may be so adapted that when it reaches predetermined positions in the cylinder 2 it opens and closes the blow-cit valve of a steam boiler or effects numerous other controlling operations in a manner which will be clear to those skilled in the art.

In the apparatus illustrated the pressure fluid acts di rectly on the piston 5 forming the movable wall.

In the apparatus illustrated the spring 24 moves downwards piston 5 forming the movable wall but other means for moving the piston downwards may be employed and the pressure fluid used to move the piston upwards may be utilized to move the piston downwards. In one adfrom cylinder 2. When the pressure of the pressure fluid on the lower face of piston 5 is released, such fluid opens the valve in the shunt passageway so that the fluid then acts on the upper face of piston 5 to move it downwards until the pressure on the lower face of the piston is restored when the valve is again closed and the piston moves upwards, the wall of cylinder 1 being provided with a bleed hole to permit the escape of pressure fluid from the space in the cylinder above the piston.

, I claim:

1. A fluid-pressure actuated control apparatus comprising a chamber. having a wall movable in one direc# tion to decrease the volume ofthe chamber by fluid pressure acting on the wall, means for moving the wall in the opposite direction, a control member connected at one end to the wall, a reservoir for hydraulic fluid, a passageway connecting the reservoir with the interior of the chamber, means for regulating flow of hydraulic fluid from the chamber to the reservoir when the wall is moved in said one direction whereby to regulate movement of thecontrol member, said flow regulating means comprising an elongated passage of gradually decreasing cross section through which a hydraulic fluid is caused to flow whereby its pressure is reduced and means for varying the cross section of the outlet of the passage, a fluidpressure release means automatically actuated when the wall has moved in said one direction to a predetermined position whereby the fluid pressure on the wall is released and the wall is moved in said opposite direction, means for the passage of hydraulic fluid from the reservoir to the interior of the chamber when said wall moves in said opposite direction, and means automatically actuated when the wall has moved in said opposite direc tion to a predetermined position to restore the fluid pressure acting on the wall.

2. A control apparatus as claimed in claim 1, wherein the elongated passage is helical and is provided by a taper thread on one of two co-operating threaded memhere.

3. A fluid-pressure actuated control apparatus comprising a cylinder having a piston forming a chamber and movable in one direction to decrease the volume of the chamber by fluid pressure acting on the piston, means for moving the piston in the opposite direction, a piston rod forming a control member and connected at one end to the piston, a reservoir for hydraulic fluid, a passageway connecting the reservoir with the interior of the chamber, means for regulating flow of hydraulic fluid from the chamber to the reservoir when the piston is moved in said one direction whereby to regulate movement of the control member, said flow regulating means comprising an elongated passage of gradually decreasing cross section through which a hydraulic fluid is caused to flow whereby its pressure is reduced and means for varying the cross section of the outlet of the passage, a fluidpressure release means automatically actuated when the piston has moved in said one direction to a predetermined position whereby the fluid pressure on the piston is released and the piston is moved in said opposite direction, means for the passage of hydraulic fluid from the reservoir to the interio'r of the chamber when said piston movm in said opposite direction, and means automatically actuated when the piston has moved in said opposite direction to a predetermined position to restore the fluid pressure acting on the wall.

4. A control apparatus as claimed in claim 3, wherein the cylinder has an inlet for pressure fluid and an outlet therefor, a valve controls rflow of pressure fluid through the outlet, and spring means are provided for snapping the valve to its open and closed positions when the piston in such cylinder reaches the predetermined positlons thereof.

5. A control apparatus as claimed in claim 4, wherein the valve is carried by a stem and the reciprocable piston and rod assembly and the stem have co-operating abutments such that, when the piston in the cylinder forming the chamber moves in said one direction to sald predetermined position, the valve stem is moved to cause the valve to snap to its open position, and, when such piston has moved in said opposite direction to said predetermined position, the valve stem is moved to cause the valve to snap to its closed position.

6. A control apparatus as claimed in claim 3, wherein the elongated passage is helical and is provided by a taper thread on one of two co-operating threaded members.

- 7. A valve for accurately controlling the rate of flow of fluids comprising means defining a cylindrical passage having a length of internal thread therein, a valve body having an external thread therearound partially rotatably disposed in said internal thread, means for conducting fluid under pressure into one end of said passage on one side of said valve body, means connected to said body for eifecting rotary adjustment thereof with consequent adjustment of the relative axial positions of said threads, one of said threads being tapered, whereby the interengaging portions of the respective threads define between them an elongated helical flow passage, the minimum cross-sectional area of which is varied incident to said adjustment.

8. A valve as defined in claim 7, wherein one of said References Cited in the file of this patent UNITED STATES PATENTS 1,920,285 Wilkins et al. Aug. 1, 1933 1,998,873 Kingsbury Apr. 23, 1935 2,252,939 McCoy Aug. 19, 1941 2,371,085 Waters Mar. 6, 1945

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