US3476015A - Valved,fluid-operated actuator assembly - Google Patents

Description

Nov. 4, 1969 E. 1.. ACKLEY VALVED, FLUID-OPERATED ACTUATOR ASSEMBLY Filed Feb. 13, 1968 2 Sheets-Sheet 1 Edward Lflckleg INVEN To]? United States Patent US. Cl. 91-401 4 Claims ABSTRACT OF THE DISCLOSURE A valved, fluid-operated actuator for reciprocating tools comprises a hollow case open at both ends. A reversing valve, preferably a two-way hollow-center valve, is mounted on one end of the case and communicates with a source of fluid under pressure as well as with the interior of the case. A cap seals oil the other end of the case. A piston is mounted for sliding movement within the case. A piston rod is connected to the piston and extends through the cap for connection to the tool. Adjustment of the valve between first and second positions causes advancement and retraction of the piston.

This invention pertains to valved, fluid-operated actuators for use in driving limb loppers, punch presses and like tools. It relates further to a novel reversing valve for use in conjunction with such actuators as well as for other applications.

It is the general purpose of the present invention to provide a valved, fluid-operated actuator assembly which may be applied to the operation of a diversity of tools, which operates smoothly, which is subject to precise control, which is relatively maintenance free, and which has a long service life.

It is a further purpose of the present invention to provide a novel two-position, hollow-center, fluid flow reversing valve which is applicable to the control of both reciprocating and rotary types of fluid-operated units, which is balanced and easy to adjust, which moves smoothly through its two position of forward and reverse drive, which may be adjusted rapidly, which does not vibrate or jar during use, and which is relatively simple and rugged in its construction.

The manner in which the foregoing and other purposes of this invention are accomplished will be apparent from the accompanying specifications and claims considered together with the drawings, wherein:

FIG. 1 is a foreshortened view in elevation of a limb lopper powered by the herein described fluid-operated actuator assembly and reversing valve;

FIGS. 2 and 3 are views in longitudinal section of the valved actuator assembly illustrating the assembly in two positions of adjustment, i.e. a FIG. 2 position which is the normal rest position of the assembly and a FIG. 3 position which is the working position of the assembly;

FIG. 4 is a fragmentary view in elevation of a spool employed in the valve unit of the actuator assembly of FIGS. 2 and 3; and

FIGS. 5 and 6 are transverse, sectional views of the spool taken along lines 55 and 6-6 of FIG. 4.

In its broad aspect, the valved, fluid-operated actuator of my invention comprises a hollow case open at both ends. A reversing valve is mounted on one end of the case. It communicates with a source of fluid under pressure, as well as with the interior of the case. Also, it includes as one of its ports a tube extending a spaced distance into the case.

A cap is sealed across the other end of the case. A centrally apertured piston is mounted in the case with the aperture receiving the tube in sliding engagement. A

3,476,015 Patented Nov. 4, 1969 piston rod is secured to the piston. It extends through the cap in sliding engagement and is adapted for connection to a device to be actuated.

The inner end of the piston rod is bored longitudinally and receives the tube. Orifices are drilled through the piston rod and piston in relative positions predetermined for registration when the piston is in its position of maximum advancement. A passageway bypasses the pressurized flow around the piston when the piston is in its advanced position. A valve is seated across the passageway. It permits passage of pressurized fluid around the piston, through the orifices, and behind the piston.

In one position of the reversing valve, fluid passes into the case, driving the piston forwardly to its advanced position wherein the fluid bypasses the piston and returns to the exhaust side of the valve through the hollow tube. In the other position of the valve, the pressurized fluid passes through the tube, through the orifices, and to the space behind the piston where it drives the piston in the reverse direction.

Considering the foregoing in greater detail and with particular reference to the drawings:

FIG. 1 illustrates the application of the valved actuator assembly to the actuation of a limb lopper. This device includes a handle indicated generally at 8, and connected to inlet and outlet hoses 9, 10 by means of which fluid under pressure is supplied to the device. It further includes a valve, indicated generally at 12, an actuator or driving section indicated generally at 14, an arm of variable length, indicated generally at 16 and a limb lopper attachment indicated generally at 18.

The limb lopper attachment is of conventional construction and is not illustrated in detail. However, it includes a frame member 20 to which is bolted a bifurcated extension 22 having bearings 24 and an arcuate, stationary knife 26 fixed to its outer end. A cooperating power-driven knife 28 is fixed to a shaft 30 which is journaled in bearings 24. One end of a link 32 is connected by means of pivot pin 34 to the end of knife 28. The other end of the link is connected by pivot pin 36 to the outer end of a draw rod 38 which extends the length of arm 16. The draw rod is connected to actuator unit 14 by means of which it is shifted between extended and retracted positions. Its inner end has a terminal longitudinal recess 39.

The construction of actuator assembly 14 and of valve assembly 12 by means of which it is controlled, is illustrated in detail in FIGS. 2 and 3.

As shown in those figures, arm 16 is comprised of a heavy, hollow cylindrical case 40 dimensioned to receive draw rod 38 in sliding engagement. The inner end of the case is drilled and tapped to provide a threaded recess 42.

The actuator assembly is housed in a case 44 which comprises a hollow cylinder open at both ends. The inner end 46 of the case is internally threaded. Its inner surface adjacent its outer end is formed with an annular recess 48 and its outer end is formed with a bore 50 of enlarged diameter.

One side of reversing valve 12', the construction of which is to be described in detail later, is threaded into the threaded inner end 46 of case 44.

A connector, indicated generally at 52 is mounted in the outer end of the case.

The connector comprises a body 54 dimensioned for reception in the enlarged bore 50 of the outer end of the case, with its inner margins seated against the shoulders therein provided. Body 54 serves as a cap for the outer end of case 44.

Connector 52 has completely through it a longitudinal opening dimensioned to receive the inner end of draw rod 38. The inner end of the opening is enlarged to provide a recess 58, the purpose of which will appear herein- 3 after. The body of the connector is sealed within the case by means of rings 60, 62.

Extending outwardly from body section 54 of the connector is threaded extension 64. This is threaded into threaded section 42 of case 40 of arm 16 and is secured in a desired position of adjustment by means of lock nut 66.

Mounted for sliding movement between reversing valve 12 and connector 52 is a piston indicated generally at 70.

The piston includes a body 72 having a threaded longitudinal bore dimensioned for receiving the threaded inner end of draw bar 38, which accordingly serves the function of a piston rod. Seal rings 74, 76, 78 are mounted on the body for establishing the desired sealed condition.

Two or more pairs of conduits 80, 80a are drilled in the body, longitudinally thereof. The conduits are angular. The component sections of each pair communicate both with the end walls and side wall of the piston body, The sections communicating with the side wall are spaced apart sufficiently to lie within the span of recess 48 in the inner wall of case 44. This affords two continuous passageways through the piston when the piston is in its FIG. 2 position, i.e. its position of maximum extension.

A hollow extension 82 extends outwardly from piston body 72. It further encases pull rod or piston 38. Its outer end is dimensioned for reception in annular recess 58'.

Valve means are provided for closing olf the passageways provided by bores 80, 80a, and recess 48.

In the illustrated form of the invention, the valve means employed for this purposes comprises a disk valve 84 seated across the outer end of the passageways and maintained in position by means of a coil spring 86. One end of the spring bears against the disk valve and the other end bears against a retaining snap ring 88 mounted on the outer end of the valve body extension.

The valve body extension further is provided with a pair of ports 90 drilled through the side wall of the extension in a location forwardly of disk valve 84. When the piston is in its advanced position of FIG. 2 these ports register and cooperate with a companion pair of ports 92 drilled through the side walls of draw bar 38.

The construction of the reversing valve 12 which controls the flow of fluid under pressure to actuating unit 14 also is shown in FIGS. 2 and 3.

The reversing valve is housed in a valve body 100 which is hollow and has aligned openings in its opposite ends. An apertured plug 102 is threaded in one of the openings, being maintained in sealed condition by means of 0 rings 104, 106. An apertured plug 108 is threaded into the opposite opening. It is sealed by means of 0 rings 110, 112.

The infeed end of the valve body is formed with an infeed conduit 116 and an outfeed conduit 118, These communicate with a pair of sockets lying within a body extension 120 dimensioned to be received in a snug fit within the flared outer end of handle 8.

The sockets are dimensioned for reception of hoses 9, by means of which fluid is fed to and exhausted from the unit. Seal rings 122, 124 preserve the desired seal.

The inner side of valve body 100, i.e. the side adjacent actuator assembly 14, is formed with an extension 126 which is threaded externally for threaded engagement with the internally threaded end of case 44 in which it is received. The resulting joint is sealed by means of O ring 128.

Valve body extension 126 is formed with a pair of ports 130, 132 which may comprise either the infeed or outfeed port, depending upon the setting of the valve, Port 132 receives in threaded engagement the threaded end of a tube 134. The outer end of the tube in turn is received in sliding engagement in the aperture present in the inner end of piston body 72.

This in effect projects the port to the area inside the piston body and inside recess 39 in piston rod 38, whereas port 130 communicates with the interior of case 44 in front of the piston. This is an important structural feature which assists materially in determining the function and mode of operation of the assembly.

A sleeve is housed within valve body 100. The sleeve fits snugly within the body. Its ends are in close proximity to, or abut, end caps 102, 108.

Sleeve 140 is provided with two pairs of opposed ports: One pair, comprising ports 142, 144 communicate respectively with ports 116, 118 of the valve body. The other pair, i.e. ports 146, 148, communicate respectively with ports 130, 132 of the valve body.

Sleeve 140 also is formed with a slot 150, FIG. 5. The slot extends inwardly from the margin of the sleeve adjacent cap 102 a predetermined distance. It serves a locking function, as will appear hereinafter.

A valve spool indicated generally at 160, is mounted for sliding reciprocating movement within the sleeve. The construction of the valve spool is shown particularly in FIGS. 4, 5 and 6.

As indicated in those figures, the spool is maintained in position by means of a pair of stems 162, 164 threaded into or otherwise secured to the valve spool. The stems are in axial alignment with each other and extend outwardly sufficiently to penetrate the apertures through valve body caps 102, 108, the seal being maintained by 0 rings 106, 112. Stem 162 extends outwardly sufficiently to be coupled to a lever 165 by means of which the valve is operated.

Valve spool 160 is contoured, shaped, and grooved to provide the passageways necessary for operation of the valve. Generally stated, the desired result is otbained by providing a pair of annular grooves on the periphery of the spool which serve to channel the fluid during the motion of piston 70 in one direction, and an inner bore which serves to channel the fluid during the reverse motion of the piston.

Accordingly there is provided a first annular groove 166 which interconnects ports 116, 130 in the FIG. 2 or idling position of the valve and, spaced therefrom, a second annular groove 168 which interconnects ports 118, 132 in the same valve position. Since in this position of the valve, groove 166 lies in the pressure end of the spool, a plurality of pressure equalizing chambers 170, 170a communicate with the groove. Pressure equalizing chamber 170a is of increased depth because it also serves as a passageway for fluid in one position of the spool. A second group of pressure equalizing chambers are formed in the opposite margin of the groove with which they too communicate.

These chambers are distributed at uniformly spaced intervals about the periphery of the spool and insure that fluid under pressure will be applied equally to all its sides. This in turn insures that the spool will be balanced by the application of fluid pressure uniformly to all of its sides so that it will not stick nor bind in operation.

Also mounted on the exterior of the spool is a pin 182 which extends radially outwardly and is received in slot 150 of sleeve 140, locking the spool within the sleeve so that it does not spin during operation of the valve, FIG. 5.

The open center configuration of the spool likewise is indicated in FIGS. 2, 3 and 4.

As illustrated, the spool is formed with a longitudinal bore 184. It extends substantially the full length of the spool and, as viewed in cross section, is substantially S- shaped in configuration with one of its segments communicating with the exterior of the valve spool in the infeed direction and the other in the outfeed direction.

A plurality of radial pressure-equalizing bores 186 also communicate with longitudinal bore 184. These serve the same function as do recesses 170, 170a, i.e. in one position of the valve they equalize the pressure on all sides of the spool, thereby preventing it from binding.

Valve spool 160 further is provided with pressure equalizing openings 190, 192. These communicate on the interior with longitudinal bore 184 and on the exterior with the inside of the valve body. They balance the spool longitudinally by insuring that equal pressure is applied to both ends of the spool, thus making possible easy and precise adjustment of the valve.

To maintain the valve spool in the idling position of the unit, there is provided a recess in the interior of valve body end cap 108. The recess contains a coil spring 196, one end of which bears against the inside of the cap and the other end of which bears against the spool. This maintains the spool normally in the position of FIG. 2.

Although the use of spring 196 in the indicated manner serves as one satisfactory means for accomplishing the desired purpose, other means such as detents suitably located on the valve stem may be employed as alternate constructions.

OPERATION The operation of the herein described valved, fluidoperated actuator assembly is as follows:

With reversing valve 12 in its FIG. 2 position, where it normally is maintained by the action of spring 196, fluid under pressure flows through hose 9, port 116, around groove 166 out through port 130 and into the inside of case 44 behind piston 70. This causes the piston to advance. When the piston reaches its FIG. 2 position, the inner ends of bore 80, 80a therein register and communicate with recess 48 in the inner surface of the case. Also, piston extension 82 enters recess 58 displacing the fluid therein and creating a fluid brake which de-accelerates the movement of the piston.

Continued application of fluid under pressure to the working face of the piston lifts disk valve 84. The fluid thereupon passes through registering ports 90, 92 into the interior of piston rod 38. It continues its flow through tube 134, valve body port 132, annular recess 168, and out through discharge port 118 into exhaust hose 10.

The flow continues in this circuit as long as reversing valve is maintained in its FIG. 2 position. This maintains piston rod 38 which, as above noted, comprises the draw bar of the limb lopper of FIG. 1, in its extended, cocked position.

When it is desired to use the implement, it is hooked over a limb and reversing valve moved to its FIG. 3 position. Thereupon the flow of fluid under pressure passes through port 116 into chamber 170a around annular groove 166, and out through port 132 into tube 134.

Tube 134 discharges the flow into recess 39 of piston rod (draw bar) 38. It then passes outwardly through registering openings 90, 92 into the space between piston 70 and cap 52.

This applies fluid pressure to the opposite side of the piston and accomplishes two functions. It holds shut disk valve 84 and moves the piston in the reverse dlrectlon.

As the piston moves, the fluid displaced ahead of 1t passes through port 130, through the hollow center 184 of the valve spool and out through port 118 into exhaust line 10.

This sequence occurs rapidly and slams shut knife 28 with the force required to sever the limb. The movement of the knife continues until the piston abuts against the body of reversing valve 12, or until pressure on operating lever 165 is released. Upon such release the valve spool is returned by the action of spring 196 to its FIG. 2 position, which extends the draw bar to its FIG. 1 position, ready for another operation of the knife.

Several important advantages of the herein described actuator assembly at once are apparent. Its operation is precise and instantaneous. The reversing valve action is smooth and facile because of its balanced construction. Since the valve is a two position valve and does not have to go through a central or neutral position, its action is exceptionally rapid.

Furthermore, the reversing valve is versatile in that it may be applied to a great diversity of fluid-operated units to be actuated, whether they are of the reciprocating class illustrated herein, or of the rotary class such as the rotary motors used to drive drills, impact wrenches and the like.

Having thus described my invention, I claim:

1. A valved, fluid-operated, actuator assembly comprising (a) a hollow case open at opposite ends,

(b) reversing valve means mounted on one end of the case,

(0) the reversing valve means having a first port communicating with the interior of the case and adapted to pass fluid under pressure in a first direction and a tube extending into the case a spaced distance beyond the first port, the end of the tube providing a second port communicating with the interior of the case and adapted to pass fluid under pressure in a second direction,

(d) a centrally apertured cap sealed to the other end of the case,

(e) a centrally apertured piston mounted in the case with the aperture receiving the tube in sealed, sliding engagement,

(f) a terminally bored piston rod secured to the piston and extending through the cap aperture in sealed sliding engagement therewith, and adapted for connection to a device to be actuated,

(g) the bore of the piston rod being aligned with and receiving the tube,

(h) abutment means on the inner surface of the cap positioned for abutment by the piston in its position of maximum advancement,

(i) orifices through the piston rod and piston in relative positions predetermined for registration when the piston is in its position of maximum advancement,

(j) a by-pass arranged to by-pass fluid under pressure around the piston when it is in its position of maximum advancement, and

(k) valve means associated with the by-pass and operative to permit the passage of fluid under pressure around the piston, through the orifices and behind the piston when the piston is in its said position of maximum advancement.

2. The actuator assembly of claim 1 wherein the abutment means on the inner surface of the cap includes a recess of restricted cross section dimensioned to receive the end of the piston in fluid-brake-forming relation.

3. The actuator assembly of claim 1 wherein the bypass comprises a pair of longitudinally spaced passageways in the piston, the passageways opening out into the opposite ends and the side wall of the piston, and a recess in the sidewall of the case registering with and interconnecting the passageways when the piston is in its position of maximum advancement.

4. The actuator assembly of claim 1 wherein the bypass opens out into the outer end of the piston and wherein the valve means comprises spring-pressed disk valve means mounted on the piston and seated across the by-pass opening.

References Cited UNITED STATES PATENTS 2,703,558 3/1955 Wilcox 9l4l6 2,746,425 5/1956 Schafer 9l4l6 3,326,304 6/1967 Johnson 9l4l6 PAUL E. MASLOUSKY, Primary Examiner US. Cl. X.R. 91--466; 92108,

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