US2921561A - Fluid cylinder and piston assembly - Google Patents

Description

Jan. 19, 1960 J. J. sENDoYKAs FLUID CYLINDER AND PIs'roN Assmw 2 sheets-sheet 1 Filed April 23. 1958 WSE Jan. 19, 1960 J. J, sr-:NDoYKAs FLUID CYLINDER AND PISTON ASSEMBLY 2 SheetsPSheet 2 Filed April 25, 1958 INVENTOR .7216/1 f 'e Wz/d.

I dr/vE/n Uaitcd Se@ f 2,921,561 Y from CYLINDER AND PrsToN ASSEMBLY y .nick :L sendoykas, si. clair shores, Mich. "i Application` April 23, 195s, serial No. 730,332

9 claims.- (cl. 121ss) This' invention relates to new and useful improvements in iluid motors.

More particularly, the iluid motor ofl this invention comprises a cylinder having a piston mounted for reciprocation therein and novel means for controlling the rate of travel of the piston as it advances in Ithe cylinder. The motor is intended to be used whereverit is desired that a part actuated by the piston move at different speeds during different portions of the piston stroke. For example, itfis contemplated that the motorbe used on' a clamping xture where it is necessary or desirable for the clamp to advance initially on a rapid traverse and then continue to advance slowly to a final clamped position. typical situation themotor is connected to the grinding headof a grinding machine so as to first advance the head on a rapidtraverse to bring the head up to thev work and thenJ move it slowlyduring the actual grinding operation, A similar situation is presented by a machine tool having tools for performing a cutting operation on a workpiece," 'In still other situations'it is desirable'to have the motor advance a tool ory other part ina series of steps which are alternately rapid and slow.

The above are typical environments in which'themotor of this invention is adapted to performl' Other typical situations will be readily apparentfto those skilled inthev art.

An'important object of the present invention isV to pro' vide a iluid motor of the above mentioned character-*that is uniquely constructed and readilyl adaptable to the par-- ticular mode of`operation required of it.

Another object of the invention is to'provide a' fluid motor of the above mentioned-character -thatis uniquelyY constructed so that it can be changedy by inexpensive meansl vfrom one mode of operation to adifferent mode of operation.

Still another object of the invention is 'to provide a' fluid motor of the above mentioned character that is in.- expensive to manufacture and ecient in operation.

Other objects and advantages of the invention' will be apparent during the course of the following description.'

In the drawing forming apart of this specification and wherein like numerals are employed to designate like parts throughout the same,

VFigure l is a longitudinal sectional View ofa' fluid 4 is a longitudinal sectional view of a modifiedl motor embodying the invention, and particularly showing a modied speed control mechanism for advancing the piston in a series of alternate rapid and Aslow movements;

In another Considered in certain of its broaderl aspects the huid motor of this invention comprises a'cylinder having a; uid inlet at one end and a fluid outlet at the other endj thereof. A tube extends from the inlet axially into the has a by-pass which extends between the inlet and the inby a needle valve or the like to a relatively restricted rate. A piston rod carried by the piston extends therefrom through the forward endof the cylinder; and the piston rod has a tubular portion which telescopically receives the'tube. Fluid also owsfrom the inlet through the tube to 'the'forward end 'thereof where it discharges through the lateral opening and into the piston rod which conducts itback into' the lcylinder behind the piston. The

piston rod is formed with a portionv or portions of relai tively small diameter andwith a portion or portions of' relatively large diameter. The portion or portions of relatively small diameter snugly tit the'terminal portion of the tube to close the opening and torestrict flow of fluidV 'into the cylinder to the by-pass." The portion 0r portions .of relatively large diameter are spaced' circumferentially. from Ithe terminal portion of the tube to provide relatively unrestricted communication'between the opening and the cylinder behind the piston. Thus,when' piston extends forwardly through a ycentral Opening 30 a relatively large'diamete'r of the rod is in register with the end of the tube, iluid ows rapidly into the cylinder and advances the piston at an essentially rapid raiteghow# ever, when a relatively small diameter portion of the rod" is in register withthe opening the restricted ow of fluid through theby-pass fills the cylinder slowlyand advances the piston atan essentially slow rate.

.It is. a feature of the invention that 'the tube can be remoyed comparatively easily and quickly from the cyl-` inder for cleaning or replacement. Anotherfeatureof the invention ie that .the piston rod is made in two parts'.l The inner part of the rod functions as, a liner, and the liner is the part of variable internal diameter which controls the. advancement rate o'f the piston. Thus, in order to change vthe advancement pattern of the piston and to adapt 'the motor for one job` or another it is merely necessary to change the liner of the piston rod. This liner is an easily formed, inexpensive part. Further'- more, the motor is uniquely constructed yso `that the liner can be easily removed and a replacement liner substituted therefore.

For 'a more detailed description of the motor, attention is directed to the accompanying drawings wherein .the numeral 10 designates a cylinder comprising a tubular- Wall 1'2 and front and rear end walls or heads 14 The forward end of the tubular wall 12 is set 4in an annu'lar groove 18 in the head 14 and the opposite end of the tubular member 12' is set in anannular groove 20 in therear head 16. Theheads 14 and 16 preferably are generally square in plan.- Screws 2 2 at the corners of therear head 16 extend forwardly exteriorally of the tubular members l12, through the front forward head 14, andnuts 24 on the screws hold the various parts of the cylinder 10 securely assembled.

A` piston 26 is mounted for reciprocationin the cylinder-f l'and apiston rod 28 connected and movable with the" in the head 14.l A threadedstud 32 on' the outer end 'oftherod 28 |adapts the latter for connection to a mechanism to be actuated thereby. i

The piston 26 comprises fnont and rear annular plates'- Paened Jan. 1a i960,

34 and 36 and an intermediate annular disk 38. The rear plate 36 has a forwardly projecting central embossment 40 which receives and snugly ts the intermediate disk 38 and is threaded on thepiston rod 28. Acollar 42 on the rod ahead of the piston 26 seats forwardly against anannular shoulder 44 on therod 28 and rearwardly against the front plate 34.Piston rings 46 and 48 have radially inwardly extending portions contined between the disk 38 `and the plates 34 and 36 respectively and outer annular portions which t snugly around the plates 34 and 36 to seal the piston against the Wall of the cylinder 10. A radially inwardly extending annular lip 50 on the rear plate 36 overlays the end of therod 28. Manifestly, when the plate 36 is tightened on therod 28, all parts of the piston assembly are pulled and held securely. together. However, the piston can be readily removed from the cylinder by removing thehead 16, and therod 28 can then be removed from the piston by unscrewing the connection between the rod and the plate 36.

Fluid is admitted into the cylinder 10 behind the piston 26 through a iitting 52 disposed centrally in therear cylinder head 16. A central passage 54 in the iitting 52 is formed with a threaded socket 56 at the outer end thereof which is adapted to receive a correspondingly threaded nipple onta pipe or tube (not shown) from any suitable source of fluid under pressure.

, As clearly `shown in the drawings` the portion of thepiston rod 28 adjacent to the piston 26 is hollow or tubular in form `and `a tube 58 connected to the fitting 52 extends inwardly from the passage 54 into the hollow portion of therod 28. A cupeshaped member 60` on the distal end of the tube 58 closes the end of the latter, and fluid traversing the tube 58 is discharged through lateral openings 62 in the tube and mem-ber 60.

In the form of the invention here shown thepiston rod 28 is formed with an inner liner 64 having a portion 66 adjacent to the piston 26 of relatively small internal diameter and aportion 68 remote from the piston of relatively large internal diameter. As shown in Figure l, the.portion 68 of the liner 64 is substantially larger in diameter than the terminal member 60 so that when theportion 68 is in register with the openings 62 fluid discharging from the tube is conducted back through therod 28 and into thecylinder behind the piston 26. Also it will be observed that flow of fluid in thisl manner is relatively unrestricted so that the cylinder 10 is able to ll relatively quickly to push the piston 26 forwardly at a relatively high rate of speed. As the piston 26 advances it of course pushes thepiston rod 28 forwardly with it to actuate whatever mechanism is attached to the rod.

. The piston continues to advance in the above manner until the relatively small portion 66 of the liner 64 moves into register with the terminal member 60, as shown in Fig. 2. The relatively small diameter portion 66 tits the terminal member 60 essentially snugly as shown in Fig. 2 of the drawing and when it moves into register with the openings 62 it prevents continued ilow` of the fluid from the tube 58 into the cylinder 10.

In order to provide for continued advancement of the piston 26 after the small diameter portion 66 of the liner 64 closes the openings 62 a by-pass is provided in thecylinder head 16. The luy-pass comprises a plurality of radial passages 70 which extend outwardly from the centnal passage 54 in the tting 52 and terminate in an annular groove 72 sealed by O-rings 74 and 76. The groove 72 communicates with an L-shaped passage 78 in thehead 16, which passage is provided with a tapered seat 80 adapted to receive the correspondingly tapered end of a needle valve 82 which extends radially into the head` 16 and is in threaded engagement therewith. The valve 82 extends radially outwardly from the head and a nut 84 on the projecting end thereof is tightened against thehead 16 to hold the valve in a selected adjusted position. In this connection, it will be observed that the valve 82 can be backed away from its seat 80 to permit a limited restricted flow of lluid through the bypass into the cylinder `behind the piston 26. Further, it will be observed that when flow through the openings 62 is stopped by the relatively small diameter portion of the liner 64 in the manner hereinabove described, fluid may continue to flow into the cylinder through the bypass at a relatively restricted controlled rate so that the piston 26 continues to advance after the openings 62 are closed but Iat a slower rate of speed. The rate of travel of the piston 26 under these conditions can of course be controlled by adjusting the needle valve 82.

Fluid in the cylinder 10 ahead of the piston 26 is discharged from the cylinder through an annular passage 86 and alateral port 88 provided in the front cylinder head 14. Conversely, fluid can be admitted into the cylinder through theport 88 and passage 86 ahead of the piston to retract the latter. As the piston 26 is retracted in the cylinder 10, fluid is: discharged through` aport 90 in thehead 16. The passage 54 and theports 88 and 90 can be connected int-o a suitable fluid system controlled by a conventional four-way valve in the usual manner to operate the motor in accordance with the requirements of the mechanism to which it is attached.

lt will be readily appreciated that thepiston rod 28 can ybe made in one piece if desired b-ut it preferably is made with a removable liner 64, as shown in the drawing. When therod 28 is made in this manner, the liner 64 can lbe readily removed if desired and replaced by a liner having a dierent arrangement of the relatively large diameter portions and the relatively small diameter portions or by a liner in which these portions are of different lengths to adapt the motor to dierent traverse and speed motions. Replacement liners can lbe kept on hand and the same motor used to service diierent machines alternately if desired. As pointed out hereinabove, therod 28 and the liner 64 can be readily disconnected from the pist-on for purpose of replacement. In order to hold the liner securely in therod 28 the annular lip 50 of the piston plate 36 extends inwardly sull'iciently far to overlap the end of the liner.

The form of the invention shown in Fig. 4 is identical to the form of the invention rst described except for the internal congurationof the liner 64. In this form of the invention a modified liner 92 is provided having a relatively large diameter portion 941, a relatively small diameter portion 96, a relatively large diameter portion 98 and a relativelysmall diameter portion 100 arranged in series from the distal end of the liner. This coniiguration of the liner 92 alternates rapid and slow movements of the portion 26. Other variations in the liner will be apparent from the forms shown.

What is claimed is:

l. A vari-able speed fluid motor comprising a cylinder having a rfluid inlet at one end and a fluid outlet at the other end thereof, la tube extending from the inlet axially into said cylinder -for conducting fluid from 4said inlet and having an enlarged terminal portion provided with a lateral discharge opening for said fluid, a piston mounted for reciprocation in said cylinder and along said tube, a by-pass between said inlet and the interior of said cylinder behind said piston providing a continuously open passage through which fluid can flow from said inlet into said cylinder at a relatively restricted controlled rate, and a piston rod movable with said piston extending through said other end of said cylinder and having a tubular portion telescopically receiving said tube Iand 'adapted to conduct uid from said discharge opening into the cylinder behind said piston, at least a portion of said rod snugly tting the terminal portion of said tube to close said opening and at least another portion of said rod being spaced from said terminal portion to provide relatively unrestricted communication Jbetween said opening and said cylinder behind said piston.

`-ilA-vz'iriable speed nid motor comprising-a cylinder having a uid inlet at one end and a iluid outlet-at the other end thereof, a tube extending from the inlet axially into said cylinder for conducting fluid from said inlet and having an enlarged terminal portion provided with a lateral discharge opening for said huid, a piston mounted for reciprocation `in said cylinder and along said tube, a by-pass between said inlet and the interior of said cylinder behind said piston providing a continuously open passage through which fluid ows from, said inlet into said cylinder at a relatively restricted controlled rate, a piston rod movable with said piston extending through said other end of said cylinder and having a tubular portion telescopically receiving said tube adapted to conduct Huid from said discharge opening into the cylinder behind, said piston, a predetermined length of said tubular portion 4adjacent to said piston snugly fitting the terminal portion of said tube to close said opening to provide a relatively slow advancement for said piston in accordance with ow of liuid through said by-pass and a predetermined length of said tubular portion remote from said piston being spaced circumferentially from said terminal portion to provide relatively unrestricted communication between said opening and said cylinder behind said piston and a relatively rapid initial traverse for the pi-ston.

3. A variable speed fluid motor comprising a cylinder having a `iiuid inlet lat one end and a tluid outlet at the other end thereof, a tube extending from the inlet axially into said cylinderfor conducting fluid from said inlet and having an enlarged terminal portion provided with a lateral ydischarge opening for said iluid, a piston mounted for reciprocation in said cylinder and along said tube', a by-pass between said inlet and the interior of said cylinder behind said piston providing a continuously open passage through which fluid can ow from said inlet into said cylinder at a rel-atively restricted controlled rate, and a piston rod connected to and movable with said piston extending through said other end of said cylinder and having a tubular portion telescopically receiving said tube adapted to conduct fluid from said discharge opening into the cylinder behind said piston, at least one portion of said tubular portion snugly fitting the terminal portion of said tube to close said opening to stop the ilow of lluid through said tube into said to ow through said by-pass, at least one other portion of said tubular portion being ysusbtantially larger in diameter than said terminal portion whereby relatively unrestricted communication is provided between said opening rand the cylinder behind the piston when said last mentioned portion is in register with .said opening.

4. A variable speed fluid motor comprising a cylinder having a lluid inlet at one end and iluid outlet at the other end :thereof a tube extending from the inlet axially into said cylinder for conducting fluid from said inlet and having lan enlarged terminal portion provided with a lateral discharge opening for said uid, a piston mounted for reciprocation in said cylinder and along said tube, a by-pass between said inlet and the interior of said cylinder behind said piston providing a continuously open passage through which fluid Hows from said inlet into said cylinder at a relatively restricted controlled rate, a valve controlling said by-pass adjustable toregul-ate the rate of tiow through said by-pass, and a piston rod movable with said piston extending through said other end of said cylinder and having a tubular portion telescopically receiving said tube-adapted to conduct iluid from said discharge opening into the cylinder behind said piston, at least a portion of said rod snugly tting the terminal portion of said tube to close said opening and at least another portion of said rod being spaced from said terminal portion to provide relatively unrestricted communication ybetween said opening and said cylinder behind said piston.

5;.'l A variable speed fluid motor-comprising'a cylinder having a fluid'inlet at one end and a fluidoutlet at the`| other end thereof, a tube extending from-the inlet axially l into said vcylinder for conducting fluid from said inlet and having an enlarged'terminal portion provided withv a lateral discharge opening for :said uid, a piston mountedl for reciprocation in said cylinder and along saidtube,4 ay

by-pass between Vsaid inlet and the interior of said cylinder behind said piston providing a continuously openA passage -through which uid can flow from said inlet into` said cylinder at a relatively restricted controlled rate, al piston rod connected to said piston and rmovable'the1'e-- with extending through the other end of said cylinderl and having a tubular portion telescopically receiving said- `tube, a removable liner disposed in and reciprocable with the tubular portion of said piston'rod and around saidL tube', and means holding said liner normally lixed in but removable from said rod, at least one portion of said.

liner snugly fitting the terminal portion of s'aid tube to close said opening, and at least another portion of saidf rod being larger in diameter than said terminal portion f and spaced therefrom to provide relatively unrestricted communication between said opening and said cylinder` behind said piston.

other end thereof, a tube extending from the inlet axially into said cylinder for conducting iluid fromsaid inlet and having an enlarged terminal portion provided with av lateral discharge opening for said fluid,` a piston mounted for-reciprocation in said cylinder and along said tube, a by-pass between said inlet and the interior of said cylinder behind said piston providing a continuously open passage through which iluid can ow from said inlet into said cylinder at a relatively restricted controlled rate, a piston rod connected to said piston and movable therewith extending through the other end of said cylinder and having a tubular portion telescopically receiving said tube adapted to conduct iluid from said discharge opening into the cylinder behind said piston, and a removable liner in and movable with the tubular portion of said piston rod, said piston being removably connected to said rod and having a central opening through which said tube extends into the tubular portion of said rod and said liner and said piston overlapping said liner at said opening to hold the liner normally in said piston rod, a portion of said lliner being of a diameter to snugly lit the terminal portion of said tube to close said opening and another portion of said liner being larger in diameter than said terminal portion so as to be spaced therefrom when in register with said opening whereby to provide relatively unrestricted communication between said opening and said cylinder behind said piston.

7. A variable speed iluid motor comprising a cylinder, a tting removably mounted centrally in one end of said cylinder and detachably fastened thereto having an inlet through which iluid enters the cylinder, a tube carried by said fitting extending from the inlet into said cylinder for conducting uid from said inlet and having an enlarged terminal portion provided with a lateral discharge opening for said fluid, a piston mounted for reciprocation in said cylinder and along said tube, a piston rod carried by and movable with said piston extending through the end of the cylinder remote from said fitting and having a tubular portion telescopically receiving said tube adapted to conduct fluid from said discharge opening into the cylinder behind said piston, a liner in and reciprocable with the tubular portion of said piston rod, means detachably holding said liner normally in said rod, a portion of said liner snugly fitting the-terminal portion of said tube to close said opening and another portion of said liner being spaced from said terminal portion to provide relatively unrestricted communication between said opening and said cylinder behind said piston, said piston rod being disengageable from said piston and removable from said cylinder to permit replacement of said liner, means providing a by-pass from said inlet to the cylinder behind said piston, means accessibile from outside said liuid motor for controlling flow of liuid through said by-pass to restrict the rate at which dluid traversing said by-pass enters said cylinder, and means providing fluid outlets inv the ends of the cylinder.

l 8. A variable speed nid motor comprising a cylinder having inlet and outlet ports at opposite ends thereof, a longitudinal tube connected at one end to said cylinder extending axially therein and communicating at the yco-nneoted end thereof with said inlet port so that iluid under pressure is admitted to said tube, a piston mounted for reciprocation in said cylinder and along said tube, a piston rod. on and reciprocable with said piston having a tubular portion telescopically receiving :said tube, said tube having a lateral orifice therein through which fluid passes from the tube into said rod and thence into said cylinder behind said piston, means carried by and movable with said piston rod slidable on said tube and cooperating with said orice to open the same during selected portions of the piston travel and to close the same during other portions of piston travel, and a Icontinuously open bypass affording a second means of communication and a controlled rate of Huid ow at all times between said tube and the portion of said cylinder behind said piston.

9. A variable speed fluid motor comprising a cylinder having inlet and out'let ports at opposite ends thereof, a longitudinal tube connected to said cylinder extending axially therein and communicating with one of said ports, said tube having a lateral orice therein through which fluid passes from the tube into said cylinder, a piston mounted for reciprocation in said cylinder and along said tube, a piston rod on and reciprocable with said piston having a tubular portion telescopically receiving said tube, said rod having portions of relatively small diameter and portions of relatively large diameter, the portions of relatively small diameter snugly tting the tube and closing saidorice to close the same `during the vportions of piston travel when said relatively small diameter portions are in register with said orice, the portions of relatively large diameter being spaced from said orice to open the same during the portions of the piston travel when said large diameter portions are in register with said orifice, and a bypass between said tube and the p0rtion of said cylinder behind said piston affording a restricted flow of Vuid at all times between said tube and a portion of said cylinder behind said piston.

References Cited in the file of this patent `UNITED STATES PATENTS

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