US2980063A - Cylinder adder - Google Patents

Description

April 18, 1961 F A, Lrrz 2,980,063

CYLINDER ADDER Filed June 30, 1958 2 Sheets-Sheet 1 F. A. LlTZ CYLINDER ADDER April 18, 1961 2 Sheets-Sheet 2 Filed June 30, 1958 (PR/0R ART l PRIOR ART nited States Patent CYLINDER ADDER Frank A. Litz, Santa 'Clara County, Calif., assignor to International Business Machines Corporation, New York, N.Y., a corporation of New York Filed June '30, 1958, Ser. No. 745,578

4 Claims. (Cl. 121-38) This invention relates to a positioning device wherein a plurality of selected discrete movements are mechanically added to provide a single output displacement, as in the device referred to as a cylinder adder in copending application Serial No. 674,416, tiled July 26, 1957. More particularly, the present invention refers to an improvement in the embodiment shown in Figs. 6 and 7 of the aforementioned copending application, reproduced herein as Figs. 3 and 4, respectively.

A cylinder adder of the type referred to may be described as a plurality of hydraulic cylinders, each containing a piston displaceable through a predetermined amount, wherein the cylinders are coupled in tandem by mechanically connecting each piston to the next subsequent cylinder. Therefore, each cylinder can be moved or translated by displacing the preceding piston. The total movement of an object coupled to the final piston will be equal to the sum of the movements of all displaced pistons.

In the embodiment shown in Figs. 6 and 7 of the above application (i.e., Figs. 3 and 4 herein) fluid is passed into the cylinders through machined openings 3S and 36 in the stationary guide way 1. Each cylinder contains ports 37 and 38 at each end thereof, which ports open into an elongated groove or chamber 39 extending longitudinally along the outer portion of the cylinder. The chamber 39 thus provides a conducting path between the fixed openings 35 and 36 and the ports 37 and 38 within the movable cylinder. This embodiment is particularly useful where a sealed unit is desired, i.e., a unit having no fitted or liexible connections which might be subject to leakage, etc. Also, it`will be observed that such a device has the advantage of not having to wor against or overcome a return biasing force and hence is more etlicient, this latter feature being attributable to the positive control of each piston in both directions by the use of 4-way valves therewith. v

While the embodiment just described performs quite satisfactorily at lower speeds, its use in positioning applications demanding higher speeds is somewhat restricted by the side-thrust resulting from the application of pressure to chambers 39 since this side-thrust produces considerable friction between guide way 1 and the periphery of cylinders 2 at a point opposite each elongated chamber 39. Further, in the foregoing embodiment, it is diiiibult to drill the relatively long bore required in guide way 1 with satisfactory precision, whereas in the present invention the use of squared cylinders facilitates a rectangular construction of guide way 1 which greatly simplifies construction of the bore.

According to the present invention the above sidethrust is completely eliminated or neutralized by arrang-V ing -adjacent pairs of cylinders one above the other in a folded or overlapping manner. Although it might be expected that the resulting stepped arrangement of the piston rods connecting adjacent cylinders would cause the cylinders to lock up in their bore due to the off-center application of forces therebetween, such is not 4 2,980,053 Patented Apr. 18, 1961 the case. In fact, no deleterious eifect attributable to the non-central location of the connecting piston rods can be observed in the actual operation of this device.

Therefore, it is an object of this invention to provide an improved cylinder adder.

It is another object of this invention to neutralize sidethrust in a cylinder adder employing elongated slotted ports.

Otherobjects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings which disclose, by way of example, the principle of the invention and the best mode which has been contemplated of applying that principle.

In the drawings:

Fig. 1 is a schematic elevation view of the invention.

Fig. 2 is a schematic perspective View .showing the balanced forces acting on the square cylinders of the invention.

Figs.v 3 and V4 are Figs. 6 and 7 respectively from the above copending application, and are included here for convenience and clarity in understanding the improvement thereover in the present invention.

Fig. 5 is an end view in sectionof the invention showing the simplified bore construction thereof.

Briefly stated, according to the invention a bore or guide way is provided having a plurality of movable cylinder blocks therein. Within each cylinder block a pair of cylinders is arranged side by side longitudinally thereof. Each of the two cylinders within each block contains a movable piston with a piston rod connected thereto. The piston rods of the two pistons in each block extend through opposite ends of each block and, except in the first and last blocks, each rod is common to two pistons, one being in'each of the adjacent blocks, thereby coupling all blocks in tandem. The rods which are left over in the first and last blocks, i.e., those not being common to two pistons, are connected to one piston and to a stationary member and an output member respectively. Each piston is positively pressure controlled in both its forward and reverse directions by 4-way valves leading to the interior of each cylinder through a pair of elongated slotted ports. One such pair is formed in the top of each block and a complementary pair in the bottom of each block. At all times one port of each pair will be under pressure while the other port of the pair is open to exhaust. In this manner there has been provided a balancing of forces acting upon each cylinder block, thereby eliminating side-thrust on the blocks.

The invention is shown schematically in Fig. 1 and is comprised of a stationary guide way 101 abutting a fixed end plate 111. Within guide way 101 is a plurality of squared movable cylinder blocks 102. Each block 102 has an upper` and a lower cylinder 103U and 103L respectively, having a movable piston 120 therein. Pistons 120 are arranged to be displaced between predetermined limits established by fixed stops 105. By adjusting stops 105; the displacements of pistons 120 may bearranged in binary fashion, if desired, as shown in Fig. 1 wherein piston 120b moves twice the distance of e, 120e twice 120b, and 120d twice 120e, etc. Pistons 120b and 120e are vconnected by a piston rod 107 v which provides the only link between blocks 102a andv 102b. Piston 120u vwithin cylinder 103U of block 102a is connected by a piston rod 108 to fixed end plate 111, shown integral therewith in Fig. l. The final or output piston 120d may be connected via its piston rod 113 to any suitable object to be displaced (not shown) which is represented here by a pointer 114 shown as part of rod 113.

To actuate each piston 120, there has been provided a solenoid operated 4-way spool valve 125 of conventional design, as described in the above application, hy-

agences draulically coupled to the interior of each cylinder 103. This hydraulic coupling may be traced via openings 135 and 136 in guideway 101, elongated grooves or chambers 139 formed in the top and bottom surfaces of blocks 102, and ports 137 and 138 leading into cylinders 103. Since chambers 139 are suiciently long to accommodate the displacement of any particular block, a fluid conducting path is always provided between the 4-way valves 125 and each cylinder 103. Each of valves 125 has only two positions and is provided with three spools 126 integrally arranged on a solenoid actuated shaft 127. The spool arrangement isr such that in one position fluid from a pressure source P will be directed to an associatedA cylinder 103 via either opening 135 or 136 and returned therefrom to sump R via the other of the openings 136 or 135. In its other position valve 125 will effect the reverse condition. In order that the pressure applied to the top and bottom of blocks 102 will be equal, it is to be understood that source P may be either a single iluid source or a number of separate sources having the same pressure. Thus, fluid under equal pressure will be directed against the top and botom of blocks 102 at ali times through one or the other of openings 135 or 136 and pass into cylinders 103 via one of the chambers 139 in each of the mentioned surfaces.

The operation of this cylinder adder is shown in Fig. 1 wherein piston 120b has been actuated to displace block 10211 from its fully retracted position (shown by dotted lines) by an amount equal to the displacement of 120i). On the other hand, pressure applied to cylinder 103U of block 102e positively retains block 10-2a against end plate 111. Likewise, pistons 120e` and 120d are pressured toward their retracted positions by propenly conditioning their associated 4-way valves 125, as shown. Thus, as best shown in Fig. 2, wherein the applied pressures for the actuated condition of the adder as shown in Fig. l are shown by a series of arrows, it can be seen that during both the actuation (e.g., 102b) and retraction (e.g., 102m, c and d) of a piston 120, one of the elongated chambers 139 on each of the opposed upper and lower surfaces of blocks 102 receives an applied fluid pressure, while the other such chamber 139 is passing fluid to sump R. It has been discovered that, not withstanding differences in the configuration and area of chambers 139, the forces acting on the opposed surfaces are substantially equal, thereby eliminating sidethrust upon blocks 102.

Finally, the invention is not to be limited to squared cylinders of rectangular cross-section since circular cylinders can obviously be folded and employed to perform in the same manner. However, the rectangular bore of guide way 101 may be easily fabricated by merely assembling four ilat sheets of material and hence is preferred since it obviates the diiculty inherent in drilling a rather long precision bore for cylinder blocks 102,.

The simplicity of such an assembled bore is shown in Fig. 5 which represents an end view, in section, of guide way 101 and associated solenoid operated 4-way valves. As thereshown, the bore for blocks 102 results from assembling a pair of side plates 150 to a pair of 4-way valve blocks 151. Each side plate 150 has a smooth, iiat machined inner surface 153 which forms the vertical walls of the bore. Both plates 150 have upper and lower shoulders 154 upon which rests the inside face 156 of valve blocks 151. Faces 156 are also machined smooth and fiat and form the horizontal walls of the bore. Thus, by simply machining shoulders 154 to the proper dimensions, the bore may be easily and accurately fabricated.

ln Fig. l the 4-way valves 125' are shown arranged with their spool shafts 127 parallel to the bore, whereas in` Fig. 5 they arer perpendicular to the bore. This discrepancy has been necessary in the schematic drawing of Fig. 1 to clearly show the operation of the invention, whereas the actual device is constructed as in Fig.v 5.

While there have been shown and desribd. and

pointed out the fundamental novel features of the invention as applied to the preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

l. A positioning device comprising an elongated guide member having a bore extending longitudinally therein, a cylinder block within said bore movable with respect thereto, said block having two cylindersl formed longitudinally therein side by side, a displaceable piston within each of said cylinders, said pistons being connected to piston rods extending through opposite ends of said block, said rods being mechanically coupled to a stationary member and a movable output member respectively, means for positively driving each piston with respect to its cylinder in both a forward and a reverse direction to displace said output member by selectively displacing said pistons, said driving means including a port at each end of both said cylinders for passing fluid thereto and therefrom, a pair of elongated `grooves associated with each cylinder and communicating therewith via said ports, said pairs being disposed opposite each other in the exterior surface of said block, and means for passing huid simultaneously into each cylinder via a selected one of the grooves of the pair associated therewith while exhausting flu-id from each cylinder via the other groove of each pair whereby the fluid forces acting upon said block normal to the longitudinal axis of said bore are maintained in a balanced condition during displacement of said output member.

2. A positioning device comprising an elongated guide member having a bore extending longitudinally therein, a plurality of cylinder blocks coupled in tandem within said bore and movable with respect thereto, each said block having two cylinders formed therein side by side and arranged with their axes disposed parallel to the direction of movement of said block, a displaceable piston within each of said cylinders, each of the pistons being mechanically coupled to one of said pistons in an adjacent block, each of said cylinders having a port at each end thereof in fluid communication with opposite sides of the piston therein, each of said blocks having a iirst and a second pair of elongated grooves formed in the exterior surface thereof, said pairs being disposed in opposed relationship and communicating with said cylinders via said ports, a plurality of openings in said guide member, each said opening being associated with one of said grooves and disposed to channel duid selectively into and out of an associated one of said cylinders, and control means for selectively directing fluid under pressure to one side of both pistons within each block via one of the grooves of each pair while exhausting fluid from the other side of the pistons within each;v block via the other groove of each of said pairs thereby to selectively displace said blocks with respect to each other while neutralizing the uid forces acting upon the blocks normal to their direction of movement.

3. A positioning device comprising an elongated guide member having a bore extending longitudinally therein, a plurality ofcylinder blocks coupled in tandem within said bore and movable with respect thereto, each said block having two cylinders formed therein side by side and disposed with their axes disposed parallel to the direction of movement of said block, a displaceable piston within each of said cylinders, each ofthe pistons being mechanically coupled to one of said pistons in an adjacent block, each of said cylinders having a port at each end thereof in iluid communication With opposite sides of the piston therein, cach of said ports being hydraulically connected to an elongated chamber extending longitudinally along the., Side of its associated block, Said chambers being disposed in pairs, each pair vcontrolling an assocated one of said cylinders, said pairs being arranged on opposite sides of each block, said guide member having an' opening extending therethrough to each of the said chambers and arranged to pass liuid to and from selected sides of the piston in each cylinder via said chambers without restricting slidable movement of the blocks, and control means for directing fluid into said cylinders via one chamber of each pair at all times while exhausting fiuid from said cylinders via the other chamber of each pair to balance the uid pressures upon said blocks normal to their direction of movement.

4. A positioning device comprising an elongated guide member having a rectangular bore extending longitudinally therein, a plurality of rectangular cylinder blocks coupled in tandem within said bore and movable with respect thereto, each said block having two cylinders formed therein side by side and with their axes disposed parallel to the direction of movement of said block, a displaceable piston within each of said cylinders, each of the pistons being mechanically coupled to one of said pistons in an adiacent block, each of said cylinders having a port at each end thereof in fluid communication with opposite sides of the piston therein, each of said blocks having a iirst pair of elongated grooves formed in one face thereof and a second pair of elongated grooves formed iu an opposite face, each pair of grooves leading to the ports of an associated one of the cylinders, and openings in said guide member for hydraulically coupling one of the grooves of each pair to a source of fluid under pressure while coupling the other groove of each pair to exhaust uid from each of said cylinders to maintain the uid forces acting Aupon the opposing faces in balance while displacing said blocks with respect to each other.

References Cited in the le of this patent UNITED STATES PATENTS White Apr. 5, 1960

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