US2924201A

US2924201A - Positioning mechanism

Info

Publication number: US2924201A
Application number: US694677A
Authority: US
Inventors: Paul A Gilovich
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 1957-11-05
Filing date: 1957-11-05
Publication date: 1960-02-09
Anticipated expiration: 1977-02-09

Description

Feb. 9, 1960 P. A. GILOVICH 2,924,201

POSITIONING MECHANISM Filed Nov. 5, 1957 2 Sheets-Sheet 1 INVENTOR.

/ PAUL G/LOV/CH B) N fibula/2041M A TTORNEZ Feb. 9, 1960 P. A. GILOVICH POSITIONING MECHANISM 2 Sheets-Sheet 2 Filed Nov. 5, 1957 which has been Unit States atent() POSITIONING MECHANISM Paul A. Gilovich, Santa Clara County, Callfl, assignor to International Business Machines Corporation, New York, N.Y., a corporation of New York Application November 5, 1957, Serial No. 694,677

8 Claims. (Cl. 121-41 This invention relates to a mechanism for positioning an element or device, and more particularly relates to a pressure activated mechanism which will generate a controlled mechanical displacement.

In an accounting machine or the like it is sometimes required to move or position an element or device with respect to the other elements of the machine. Thus, it may be desired to move a device such as a magnetic transducer across a magnetic storage file to a particular track thereon for recording or reading information. In such a case, the positioning of the transducer must be precise with respect to the magnetic storage file, since it isnot unusual to record one hundred or more tracks side by side upon the magnetic surface of the file, and it is essential that the transducer be positioned accurately upon a selected track.

It is an object of this invention to provide a simple device for mechanically driving or moving an element such as a transducer head to a selected one of a plurality of possible positions It is a further object of this invention to provide a pressure responsive positioning device which may be electrically controlled byactuating a selected one of several solenoid valvm and wherein a mechanical displacement will be generated corresponding to the particular valve that was actuated.

A further object of this invention is to provide positioning apparatus wherein two devices or more are coupled in tandem for producing a fine and a coarse drive and wherein each of the, devices is simply controlled by the operation of a single hydraulic valve.

Briefly stated,'according to this invention a positioning device includes a housing with a movable element therein. Fluid under pressure is admitted into the housing on both sides of the movable element. A plurality of exhaust ports are positioned uniformly along the housing, and through a system of control valves a single selected exhaust port may be opened to expel fluid from the housing. If the opened port is on one side of the movable element, the pressure on that side will be reduced causing the element to move in that direction and to eventually center itself over the opened port. In a-preferred embodiment of this invention, 'the housing may be 'arcuate in shape and the movable element may be a vane rotatable with a shaft for transmitting the mechanical displacement to an output device. If two or more of such devices are tandemly coupled, the displacement of the vane of the first device Fig. 1 is a perspective view with parts broken away of a pair of tandemly coupled positioning devices according to this invention.

Fig. 2 is ahorizontal sectional view along the broken line 2--2 of Fig. 1. Y

Fig. 3 is a similar horizontal sectional view of further apparatus constituting another embodiment of this invention. ,1

Asshown in Figs. 1 and 2, one form of the positioning apparatus of. this invention may be arranged with ,a first positioning device including a housing 11 with a movable element or vane 12 therein. The vane 12 is .attached to and rotatable with a shaft 13 which may be mechanically coupled to a second positioning device. The second device may likewise include a housing 14 with a vane 15 movable therein. The vane15 is similarly attached to and rotatable with an output shaft 16 whichin turn may be mechanicallytcoupled to an access arm 17 supporting a device such-as a magnetic transducer 18. Fluid under pressure is admitted to the housings 11 and 14 through pressure or

inlet ports

19 and 20 which are positioned at .opposite ends of each housing thereby admitting fluid spaced ports or apertures 22.

Considering the operation of the first pressure responsive device, it will be appreciated that the interior of the housing 11 is divided into two cavities by the vane 12. With hydraulic fluid under pressure on-both sides of the vane 12, there will ordinarily be no tendency for the vane to move since the pressures will be balanced on each side thereof. However, if an exhaust port is opened and fluid is permitted to escape from one of the cavities, the pressure will drop on that side-causing the vane 12 to move in that direction. When the end of the vane 12 moves over and covers the open'port, the hydraulic pressure may cause proportionally smaller displacement of the sec- 0nd device-which displacement will constitute a fine adjustment to be added to the coarse adjustment produced by the vane or other movable element of the second device.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings which disclose, byway ;of example, the principleoftheinvention and the best mode the'drawings:

contemplated of applying that principle.

will build up and equalize on both sides of the vane thereby holding the vane over the open port. In a subsequent operation, the first port may be closed andanother port may be opened to again cause the vane to move and center over the second open port. Thus, it may be seen that the vane 12 will move incrementally in either direction and will center itself upon an open exhaust port.

For good operation of the port-seeking vane, it is not necessary that it fit so snugly in the housing that there be no hydraulic leakage therearound. Since both cavities within the housing are under pressure, the leakage around the vane will be of little consequence. The end dimension of the vane 12 should correspond with the size of the exhaust ports 22, such that the vane will substantially cover and block the flow of fluid from the open exhaust port. It has been found that good operation results when the width of the vane is slightly less than the width of the exhaust ports, since the escape of fluid must be equal from each side of the vane in order to equalize the pressures on opposite sides of the vane, and therefore the vane will move to an exact position bisecting the area of the selected exhaust port.

The fundamental reason for the decreasein pressure on that side of the vane 12 where an exhaust port 22 has been opened lies in the fact that only a limited fluid flow is possible through each intake port 19-20 which may be insuflicient to replace the fluid exhausted. The pressure on one side of the vane may be caused to drop off more sharply by placing a flow restricting means such as an orifice in each of pressure conduits 32. However,- a

satisfactoryoperation of port-seeking apparatus has been O n w o tns ns rs l o t rig ins der q sran b e ys. w a

.3 vp ...t .fl i imi aticnsotttbs cenduits per se.

A further advantage may be gained by using a vane which is of smaller dimension than the width of the exhaust port, since the hydraulic fluid is continually expelled to the low pressure sump when the vane stands upon an open port between successive positioning operations. Thus, the pressure of the System is reduced between operations and the energy expended by the pump or other pressure means .is reduced. When the next positioning operation is commenced, the first port is closed and another port is opened, and the fluid pressure will then build up behind the vane as it begins to move. During the valve operations at the beginning of a stroke, the pressure is reduced, and therefore a simple ball check valve arrangement as shown at 23 (Fig. 1) is suflicient for use in the apparatus of this invention.

As shown in Fig. 1, each of the exhaust ports 22 has associated therewith a control valve 23 which may have a spring 24 urging the valve part against a seat to retain the valve in a closed position. When the valve is actu-.

ated and is opened, fluid from within the housing 11 is permitted to exhaust back to a low pressure sump. Since there are a number of the exhaust ports 22 and valves 23, the problem of piping therefrom may be greatly simplified if the low pressure sump comprises an outer tank 25 which may completely enclose both of the pressure responsive devices. Thus, it may be seen from Fig. 1 that the housing and vane arrangements are actually mounted within the sump tank and are surrounded by the oil or other suitable hydraulic fluid. Therefore, no pipingis required from the exhaust valve 23 since the fluid is expelled into the surrounding low pressure sump.

A solenoid operating mechanism 26 is controllably associated with each of the valves 23 and may be conveniently mounted over the tank 25 and therefore be abovethe hydraulic fluid. .The first housing 11 may be fixedly mounted on leg brackets 27 which hold the housing slightly above the floor of the sump 25 to permitflow of oil thereunder. Since the housing 11 is fixed and stationary, the mechanical coupling between the solenoids 26 and the valves 23 may be a rigid tube 28 with a wire or push rod 29 therein.- The housing of the second device 14 is rotatably mounted on a pedestal 30 which likewise supports the shaft 16 and the vane 15. Since this housing 14 must be free to move somewhat, the mechanical couplings between the solenoids 26 and the valves 23 associated therewith must be flexible in nature and there fore may be a flexible tube and wire arrangement 28, 29'. If the solenoid control mechanisms 26 were mounted directly upon the housings 11 and 14 and within the oil or hydraulic fluid, then the tube and wire couplings could be eliminated.

As shown in Fig. 2, the pressure ports 19 and are connected to hydraulic conduits 32and 32' for passing hydraulic fluid under pressure from a pump or other.

pressure device (not shown) external to the tank to the two

pressure ports

19 and 20. Since the housing 11 is fixed or stationary, the conduits 32 leading thereto may be rigid; however, since the second housing 14 must be free to move between limiting stops 33, the conduits 32' must be flexible in nature. Although the conduits 32 and 32'constitute a means for passing fluid under pressure into the housings 11 and 14, and in this case are connected to pass the fluid under pressure from outside The mechanical couplings between the two devices could also be a pinion and rack arrangement wherein a toothed pinion is mounted on a shaft 13 and engages cooperating teeth out into the circular periphery of thehousing 14. Although the pinion and rack coupling may be deemed the equivalent of the flexible band 34, it must be pointed out that the positioningapparatus of this invention may be required to produce'precise and accurate displacements of anoutput device such as .the transducer 18, and

any backlashor play resulting from gear teeth would be very undesirable. To connect the shaft 16 from the second device to the accesslarm arrangement17, a further flexible band 37 maybe employed in a manner similar to the band 34 wherein a set screw 38 will prevent slippage about the shaft16 and wherein the ends are lashed to the access arm output device by a further pair of set screws 39.

Fig. 3 illustrates another embodiment of this invention wherein the output displacement or movement is linear in nature rather than rotational as was the case of the apparatus shown in Figs. 1 and 2. The apparatus of Fig. 3 includes a first pressure actuated device with an arcuatehousing 11- and a vane 12 movable therein in the same manner as discussed heretofore in connection .with the apparatus in'Figspl and 2. However, the second tandemly coupled device .shown in Fig. 3 comprises a cylinder 40 constituting the housing and a pistonH41 movable therein. As in the previous apparatus, a band 34 is .wrapped around the shaft 13 and secured thereto with a sure ports 43 which connect by a flexible conduit 44 to the pressure conduits 32 associated with thefirst device. The cylinder 40 contains a plurality of uniformly spaced exhaust ports '42, each having a controlvalve 43 associated therewith. With pressure being admitted .to the cylinder at .each end thereof,.any unbalance may be created by opening a selected pressureport by energizing 1 a solenoid 44 by means of flexible electricalcables45.

The piston 41 will thence move toward the lower pressure andtoward the opened port. As shown in Fig. 3, a

"single port-valve 43' is opened to reduce the pressure of the sump 25, it may be appreciated that the tank sump 25 may be enlarged somewhat to provide additional room for the pressure pump therein and in which case the

conduits

32 and 32' need not extend to and through the walls of the sump tank 25.

As shown in Figs. 1 and 2, the mechanical coupling be-,

' tween the shaft 13 of the'first device'and the arcuate *housing '14 of the second device comprises a flexible band 34 which iswrapped around and secured to the shaft 13 -by means such as a set screw 35; The band also lies along the circular periphery of the housing14'and may attached thereto'by further set screws or studs 36.

causing the piston 44 to move in the direction of that 7 opened port-42 until it becomes centered overthat port and the hydraulic pressures on each side 'of the piston then balance. As in the case of the port-seeking vane,

the piston 41 need not fit so snugly within the cylinder 40 that oil is prevented from leaking' therearound. Likewise, as in the case of the vane, the width of the piston.

41 may be equal to or slightly less than the width of the exhaust ports 42. I

A piston rod,46 extends through the walls on both sides of the sump tank 25Aand through the ends of the cylinder 40 whereinit is secured to the piston 41. The piston rod 46 is slidable axially and constitutes an output member for the displacement or positioning of the device. In this case, a simple pointer 47 is attached to the end of the piston rod 46-and schematically represents the device or element to which the displacement and positioningof this apparatus is imparted. It may be further appreciated that'the piston rod 46, being slidably mounted with bearings 48, will be self-supporting and that through the bearings 49 in the'ends ofthe cylinder 40 the cylinder will be slidably supported upon the piston rod 46. Thus, the piston'rod 46 in addition 'to being'theoutput device also constitutes the slidable supporting structure for the cylinder '40. a

While there have been shown and described and pointed out the fundamental novel features of the invention as applied tothe preferred embodiment, it willbe understood that various omissions and subst t t ons and shanges 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:

1. Positioning apparatus comprising a plurality of pres sure responsive devices coupled in tandem, each of said devices including a housing and a movable element Within the housing, a mechanical means coupling the movable element of the first device to the housing of the second device, the housing of each device having ports for passing fluid under pressure to both sides of the movable element therein, the housing of each device having further ports intermediately spaced between the pressure ports for exhausting fluid therefrom, and valve means hydraulically coupled to each device for opening a selected port and for causing a selected movement of the element in the housing, said mechanical coupling means being operable to move the housing of the second device by an amount which is proportionally less than the movement of the movable element in the first device whereby both a coarse and a fine positioning are obtainable.

2. The positioning apparatus according to claim 1 wherein at least one of the devices comprises an arcuate housing with a rotatable vane therein.

3. Positioning apparatus comprising a first pressure re sponsive device and a second pressure responsive device, each of said devices including a housing and a movable element therein, the housing of the first device being fix edly mounted, the housing of the second device being movable, mechanical means coupled between the movable element in the first device and the housing of the second device, the housing of each device having pressure ports at each end thereof for admitting hydraulic fluid under pressure into the housing on both sides of the movable element, the housing of each device further having a plurality of exhaust ports spaced between the pressure ports, and a control valve hydraulically coupled to each of the exhaust ports whereby a single selected port may be opened in each device to cause movement of the element therein, said mechanical means being operable to move the housing of the second device by an amount which is proportionally less than the movement of the movable element of the first device, and whereupon a total positioning movement will be developed in accordance with the selection of exhaust ports.

4. The positioning apparatus according to claim 3 wherein both of the pressure responsive devices includes an arcuate housing enclosing a vane which is fixed to and rotatable with a shaft, the shaft of the first device being mechanically coupled to rotate the arcuate housing of the second device, the shaft of the second device being a mechanical output for a selected positioning movement generated by the combined selective movements of the vanes in both devices.

5. The positioning apparatus according to claim 3, wherein the first pressure responsive device includes an arcuate housing enclosing a vane which isfixed to and rotatable with a shaft, and wherein the second pressure responsive device includes a cylinder having a piston therein, the shaft of the first device being mechanically coupled to move the cylinder of the second device, said second device having a piston rod fixed to the piston and providing a mechanical output for a selected positioning movement which is generated by the combined selective movements of the vane of the first device and of the piston of the second device.

6. Positioning apparatus comprising a first pressure responsive device and a second pressure responsive device, each of said devices including an arcuate housing and a vane rotatably mounted therein, the housing of each device having inlet ports for admitting hydraulic fluid under pressure into the housing on both sides of the vane and having a plurality of exhaust ports spaced uniformly between the inlet ports, a control valve hydraulically coupled to each of the exhaust ports for opening a selected one of the exhaust ports in each of the devices, the vane in the first device being mechanically coupled to rotate the housing of the second device to an angular displacement proportional to and less than the angular displacement of rotation of the vane in the firstdevice, whereby the vane of the second device will produce an output displacement which is the combination of direct displacement of the second vane with a proportionately reduced displacement of the first vane.

7. Positioning apparatus comprising a first hydraulic device, a second hydraulic device and mechanical-means coupling the first device to the second device, said first hydraulic device including an arcuate housing with a vane rotatably mounted therein and further including means for admitting hydraulic fluid under pressure into the housing on both sides of the vane, said housing having a plurality of uniformly spaced ports for exhausting fluid from a selected point for rotating the vane thereto, said second hydraulic device including a cylinder having a piston slidable therein and further including means for admitting hydraulic fluid under pressure into the cylinder on both sides of the piston, said cylinder having a plurality of uniformly spaced ports for exhausting fluid from a selected point for moving the piston thereto, said cylinder being mounted to move axially, said mechanical means being coupled between the vane and the cylinder and being operable to move the cylinder by an amount substantially equal to the spacing between the ports of the cylinder.

8. The positioning apparatus according to claim 7 wherein the piston is fixed to a piston rod and wherein said piston rod slidably supports the cylinder to permit axial movement thereon.

References Cited in the file of this patent UNITED STATES PATENTS 691,692 Von Zweigbergk Jan. 21, 1902 2,045,140 Horton et al June 23, 1936 2,219,965 Smitt Oct. 29, 1940 2,391,578 Lawrence Dec. 25, 1945 2,398,997 Berry et a1. Apr. 23, 1946 2,481,426 Hull Sept. 6, 1949 2,825,307 Enyeart et al Mar. 4, 1958