US3538814A - Double-acting hydraulic cylinder and control therefor - Google Patents

Description

United States Patent Inventor Earl II. Fisher 630 Casgrain Avenue, St. Laurent, Montreal 9, Quebec, Canada Appl. No. 691,001 Filed Dec. 15, 1967 Continuation-impart of Ser. No. 423,073, Jan. 4, 1965, Patent No. 3,369,459 Patented Nov. 10, 1970 DOUBLE-ACTING HYDRAULIC CYLINDER AND CONTROL THEREFOR 2 Claims, 8 Drawing Figs.

US. Cl 91/39, 91/50, 91/51, 92/13, 92/130 int. Cl ..F15b 21/02, F15b 13/04 Field oi'Search 91/51, 39,

50(Cursory); 92/85. 13(Cursoryl. (Complete) References Cited Macks Ambrosini...

Lucien Bentley et a1 Bays et al FOREIGN PATENTS UNITED STATES PATENTS Lynott 5/1942 France Primary Examiner-Paul E. Maslousky Attorney- Fetherstonhaugh & C0.

ABSTRACT: A double-acting hydraulic cylinder having separate fluid inlet and exhaust ports at each side of its piston. Pump means deliver fluid into the cylinder through the inlet ports and valve means on the exhaust ports control fluid flow and application of fluid pressure to opposite sides of the piston. The valve means are power-actuated entirely independently of relative cylinderand piston movement.

Patented Nbv. 10, 1970 1 3,538,814

" 11111111111114 r INVENTOR EARL H. FISHER ATTORNEYS Patented Nov. 10-, 1970 Sheet INVENTOR EARL 'H. FISHER ATTORNEYS DOUBLE-ACTING HYDRAULIC CYLINDER AND CONTROL THEREFOR RELATED APPLICATION This application is a continuation-in-part of my copending application Ser. No. 423,073, filed Jan. 4, 1965, now Pat. No. 3,369,459 dated Feb. 20, 1968.

BRIEF SUMMARY My aforementioned copending application disclosed a double-acting hydraulic cylinder having separate fluid inlet and exhaust ports at each side of its piston, with inlet and exhaust valve for the respective ports actuated independently of relative cylinder and piston movement so that variations in length of stroke and rapid vibrations are possible by appropriate actuation of the valves.

The present invention carries forward the broad characteristics as above outlined, and its principal object is to substantially simplify the valve arrangement and, at the same time, materially expand the functional scope and utility of the cylinder assembly so that it may be effectively employed in various different environments where a variable length of stroke is desired, or where rapid vibrations are to be produced without any substantial stroke at all.

With the foregoing more important object and features in view and such other objects and features as may become apparent as this specification proceeds, the invention will be understood from the following description taken in conjunction with the accompanying drawings, wherein like characters of reference are used to designate like parts, and wherein:

FIG. 1 is a view, largely diagrammatic and partly in section, of a hydraulic system embodying the cylinder and valve means of the invention;

FIG. 2 is an enlarged sectional view of one of the exhaust valves, taken substantially in the plane of the line 22 in FIG. I;

FIG. 3 is a fragmentary view, similar to that in FIG. I, but showing a modified arrangement embodying two pumps;

FIG. 4 is a fragmentary sectional view of the cylinder equipped with fluid shock absorbers or accumulators: at the inlet ports;

FIG. 5 is a view similar to that in FIG. 1 and including auxiliary work engaging cylinders on the piston rod;

FIG. 6 is a view, partly in elevation and partly in section,

, showing the cylinder equipped with resilient stroke controlling means;

FIG. 7 is a view similar to that in FIG. 6 but showing a modified embodiment of the stroke controlling means; and

FIG. 8 is an elevational view of a typical cylinder arrangement for producing rapid vibrations or impacts without any substantial stroke.

DETAILED DESCRIPTION Referring now to the accompanying drawings in detail, and more particularly to FIGS. 1 and 2, the numeral 10 designates a double-acting hydraulic cylinder including a casing 11 having a piston 12 therein, the piston dividing the interior of the easing into a pair of chamber portions 13, 13', each having a fluid inlet port 14 and an exhaust port 15 separate from the inlet port, as will be apparent. The piston 12 is carried by a piston rod 16 which projects at least at one end to the outside of the casing 11, although the piston rod may project at both ends as shown in the drawings.

The casing 11 and the piston 12 are reciprocable relative to each other and, as far as the invention is concerned, the casing may be fixed and the piston reciprocable, or vice versa, or both may move at the same time under certain conditions. If the casing is to be fixed, it may be provided with a suitable mounting lug 17 for securing the same to supporting structure, although any other suitable mounting may be utilized.

Hydraulic fluid under pressure is supplied to the two chambers 13, l3by a suitable pump 18 having an intake line 19 extending from a fluid reservoir 20 and also having an intake manifold communicating as at 21 with the two inlet ports 14, so that both chambers 13, l3'may be pressurized by fluid simultaneously and constantly. The exhaust ports 15 are connected by lines 22 to a pair of exhaust valves 23, 23', respectively, the outlet or discharge lines 24 of these valves returning fluid to the reservoir 20. The valves 23, 23' may be of any suitable type, the example illustrated in FIG. 2 showing a rotary type valve having a hollow rotor 25 in a housing 26, the rotor having a set of circumferentially spaced ports or openings 27 which are successively registrable with the fluid exhaust line 22 of the associated cylinder exhaust port 15, so thatas the rotor is rotated, the valve is alternately closed and opened to respectively block and permit flow of fluid from the associated cylinder chamber. After entering the interior of the rotor through the openings 27, the fluid is discharged from the valve through the discharge line 24, as aforesaid.

As already indicated, this particular valve construction is shown only as an example, and regardless of what type of a valve is used, it is significant to state that the valves 23, 23' are actuated separately and entirely independently of relative reciprocation of the cylinder casing 11 and piston 12. In the illustrated example the valves are rotated by suitable motors 28 operatively connected to the valves by suitable drives 29. As such, the valve actuation is not only independent of actuation of the cylinder 10, but the two valves 23, 23' are independently driven by the two separate motors 28, which may be desirable under some conditions where opening and closing of the two valves is to be out-of-phase by varying degrees. Under other conditions a single motor drive may be provided for both values in a fixed out-of-phase relationship, so that one valve is fullyopen while the other is fully closed. In any event, the critical feature is that of valve actuation independent of cylinder or piston reciprocation, as already stated. This not only permits variations in the length of the stroke of reciprocation, but also facilitates production of rapid vibrations or impacts without any substantial stroke at all, as will be hereinafter explained.

In operation, fluid under pressure is constantly delivered by the pump 18 into both cylinder chambers 13, 13' and, assuming the exhaust valve 23 to be open and the valve 23' closed, fluid will escape from the chamber 13 through the open valve 23 but fluid pressure will build up in the chamber 13, thus forcing the piston 12 to the left as viewed in FIG. 1. On the other hand, when the valve 23' is open and the valve 23 is closed, the piston will move to the right, both these conditions assuming that the cylinder casing is fixed and the piston is reciprocable. As actuation of the valves 23, 23 continues, reciprocation of the piston (or cylinder) will result, and it will be apparent that inasmuch as the valve actuation is not dependent upon cylinder or piston movement, the length of stroke may be varied by simply actuating the valves at a faster or slower rate so that application of fluid pressure to the opposite sides of the piston is appropriately reversed at any desired point along the length of the stroke. Indeed, the stroke may be so short as to produce very rapid vibrations of a small amplitude in certain types of installations where the cylinder is to be used as a source of vibrating energy. Also, in similar such installations there may not be any stroke at all, but application of fluid pressure to the alternately opposite sides of the piston will produce reactive impacts of a high frequency for transmission to the work through either the cylinder casing or the piston rod.

It is to be noted that only the exhaust valves 23, 23' are used to control the flow of fluid through the cylinder chambers and that in this manner the structure is considerably simplified by I elimination of valves at the inlet ports 14. However, inlet valves (not shown) may be provided if so desired in addition to the exhaust valves, for example as disclosed in my aforementioned application Ser. No. 423,073. If inlet valves are utilized, it is essential that they be as close as possible to the cylinder to minimize delay in travel of fluid from the inlet to the exhaust. However, when inlet valves are omitted and the cylinder is loaded with fluid pressure right up to the exhaust valves, the exhaust valves may be located remotely from the cylinder as convenient, without affecting the cylinder operation by delay in fluid travel.

A slightly modified arrangement of the hydraulic system appears in FIG. 3 wherein two separate pumps 18, 18' are used instead of a single pump to deliver fluid to the two intake ports 14 of the cylinder. Fluid from the reservoir 20 is delivered by a manifold 19a to the two pumps, but otherwise the arrangement of FIG. 3 is the same as that of FIG. 1, including the exhaust valves, etc., as already described.

FIG. 4 shows another modification which may be used in the arrangement of either FIG. I or FIG. 3 and in which fluid shock absorbers or accumulators 30 are provided in communication with the fluid supply lines leading from the pump or pumps to the cylinder inlet ports 14. These accumulators contain a charge of inert gas such as nitrogen, for example, separated from the fluid by a movable partition or piston 31, the cushions of gas serving to absorb any fluid shocks in the system and also to provide instant response to any changes which the system may encounter.

FIG. 5 illustrates the double-acting cylinder provided on the external portions of its piston rod 16 with auxiliary hydraulic cylinders 33, 34, 34 for engaging various work in a manner similar to that disclosed in the aforementioned application Ser. No. 423,073. Manifestly, the arrangement may embody only one pump 18 as shown, or two pumps l8, 18' as in FIG. 3, the single pump being shown for illustrative purposes only.

Each of the external or auxiliary cylinders 33, 34, 34' contains a piston 35 rigid with the piston rod 16 and the cylinders are reciprocable relative to their respective pistons so that in effect the auxiliary cylinders are longitudinally adjustable on the piston rod. Each cylinder has conventional fluid connections 35 whereby fluid pressure may be applied selectively to opposite sides of the associated piston, thus causing the cylinder to slide along the piston rod in one direction or the other.

Numerous different arrangements are possible in applying the auxiliary cylinders to the work and within the context of this invention these need not be detailed. However, by way of an example, the cylinders 34, 34 may be provided with jaws 37 for clamping a piece of work therebetween, as for example a rail, if the apparatus is used for setting or lining of railroad track. The cylinders 34, 34 may also be provided on the opposite end of the piston rod 36 in place of the cylinder 33, or two cylinders such as the cylinder 33 may be used at the opposite ends of the piston rod, if the apparatus is used for tamping of track ballast, or in forging hammers, pile drivers, and the like. It suffices to say that the auxiliary cylinders afi'ord facilities for clamping or otherwise engaging the work in a manner which permits adjustment longitudinally of the piston rod 16, and that the work so clamped may be shifted, vibrated or otherwise subjected to force or impact energy when actuation of the cylinder 10 occurs. by control of the exhaust valves 23, 23.

In the example shown in FIG. 8 emphasis is placed on the impact producing ability of the cylinder 10 without any substantial reciprocation of the piston relative to the cylinder. As shown, the device is placed between two opposing walls, or the like, 38, with one end of the piston rod 16 abutting one wall and the other wall being in abutment with the auxiliary cylinder 33 at the other end of the piston rod. Fluid under pressure admitted to the right hand end of the auxiliary cylinder 33 will firmly wedge the device between the two walls, and reciprocation of the cylinder l0 relative to the piston 12 may be prevented by securing the mounting lug 17 to a suitable support fixed with respect to the walls 38. If the exhaust valves of the cylinder W are then actuated so that fluid pressure is applied alternately to the opposite sides of the piston 12, there will be no reciprocation of the piston relative to the cylinder, or vice versa, but rapid reactive impacts will be applied alternately to the piston from its opposite sides and such impacts will be transmitted through the piston rod 16 and through the auxiliary cylinder 33 to the walls 38. In an operation of the type given in this example, the walls 38 may be either vibrated or subjected to'a gradual spreading apart or breakdown, in which event the progressively increasing span between the walls will be compensated for by longitudinal adjustment of the auxiliary cylinder 33 on the piston rod 16 and the cylinder unit 10 will still remain without any substantial amount of reciprocation.

FIGS. 6 and 7 illustrate other adaptations of the double-acting cylinder 10 in an environment where the stroke of reciprocation, already variable by timing of the exhaust valves as previously explained, may be further controlled by resiliently compressible means outside the cylinder. In FIG. 6, the projecting end portions of the piston rod 16 carry resiliently compressible blocks 40 of rubber, or the like, which are interposed between the ends of the cylinder and washers 41 held in place on the piston rod by adjustable nuts 42. Actuation of the exhaust valves of the cylinder will produce a tendency of the piston rod to reciprocate, but such reciprocating movement will be restrained by the resilient blocks 40 and a complex, varied and controlled stroke may be obtained, depending upon, for example, the resiliency of the blocks, adjustment of the nuts 42, speed of reciprocation, pressure and volume of fluid, etc.

In FIG. 7 the piston rod 16 projects only from one end of the cylinder and is surrounded by a coil spring 45 having one end secured as by welding to an attachment plate 46 suitably fastened to the adjacent end of the cylinder as by the screws 47. The other end of the spring is secured, as by welding, to a plate 48 having a rotatable connection 49 to an adjusting nut 50 on a screw-threaded end portion of the piston rod. The spring 45 functions to control reciprocation of the piston rod in a manner similar to the blocks 40 in the embodiment of FIG. 6, but since the ends of the spring 45 are secured to the components 46, 48 and since the distance between these components is predetermined by adjustment of the nut Stl, the spring will effectively control movement of the piston rod in both directions, by compression in one direction and stretching in the other, so that use of similar resilient restraining means at the opposite end of the cylinder is not necessary. It will be apparent that, if desired, the resilient restraining means of FIGS. 6 and 7 may be suitably embodied inside the cylinder 10, rather than being disposed exteriorly thereof as shown.

lclaim:

l. The combination of a double-acting hydraulic cylinder assembly including a casing having a chamber therein, a piston positioned in said chamber and having a piston rod projecting at least at one end to the outside of the casing, said casing and said piston being reciprocable relative to each other, said piston dividing said chamber into a pair of chamber portions, said casing being provided with a pair of hydraulic fluid inlet ports communicating with the respective chamber portions and with a pair of separate exhaust ports communicating with the respective chamber portions at points spaced from the respective inlet ports whereby fluid may flow unidirectionally through the chamber portions from the inlet ports to the exhaust ports, pump means delivering fluid under pressure into said chamber portions through the respective inlet ports a pair of rotary exhaust valves connected to the respective exhaust ports for controlling the flow of fluid out of said chamber portions, power-actuated means separate from and independent of relative casing and piston reciprocation for actuating said valve means, means recirculating fluid from said exhaust valves to said pump means, abutment means provided on said piston rod exteriorly of and in spaced relation from said casing, and resiliently compressible piston rod stroke controlling means interposed between the casing and said abutment means.

2. The combination as defined in claim ll wherein said abutmerit means are adjustable longitudinally of the piston rod.

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