US2815254A - Fluid cylinders - Google Patents

Description

Dec. 3, 1957 R. SQMAN ET AL 2,315,254

FLUID CYLINDERS Filed March 2a, 1956 2 Sheets-Sheet 1 INVENTORS ROBERT SOMA/Y WILLIAM E. PARKERI CHAUNCEY LOUCKS ATTORNEY I Dec. 3, 1957 FLUID CYLINDERS R. SOMAN ET AL 2,815,254

Filed March 26, 1956 2 Sheets-Sheet 2 il s \\1 I 2:

IN V EN TORS ROBERT SOMAN W/LL/AM EAR/(ER CHAU/VCEY LOUC/(S BY Z/Wwmu A TTOR/VKY htates Patent @fiice 2,815,254 Fatented Dec. 3, 1957 Loncks, Warren, ()hio, assigmors to The Federal Machine & Welder Company Application March 26, 1956, Serial No. 574,057

6' Claims. (Cl. 309-6) The present invention relates to fluid cylinders, more particularly to fluid cylinders of the type having means for lubricating the relatively movable parts thereof, and the principal object of the invention is to provide new and improved fluid cylinders of such character.

The problem of lubricating fluid cylinders, particularly certain types of air cylinders and the like, has never been satisfactorily solved. Attempts have been made to lubricate such cylinders; however, even the best of the prior constructions were high in initial cost and were troublesome to maintain since most required a multiplicity of working parts.

The present invention is characterized by simplicity, low initial cost and longv trouble-free operation. These and other advantages will readily become apparent from a study of the following description and from the drawings appended hereto.

In the drawings accompanying this specification and forming a part of this application, there is shown, for purpose of illustration, an embodiment which the invention may assume, and in these drawings:

Figure l is an elevational View illustrating an appli cation for which the present invention is particularly well suited,

Figure 2 is an enlarged longitudinal sectional view of the invention,

Figure 3' is an enlarged, fragmentary view of a portion of the device shown in Figure 2, and

Figure 4 i a view similar to Figure 3 but showing certain parts in another position.

The fluid cylinder herein illustrated is adapted to be employed as a cushioning device for a press; however, it is to be understood that the present invention has application in fluid cylinders adapted for other uses.

The press It) illustrated in Figure 1 may be of any conventional design and is herein shown to comprise a movable platen ill and a fixed support 12. The usual power mechanism (not shown) may be employed to reciprocate platen 11 toward and away from support 12. Press It further incorporates a cushioning device 13 which illustrates an embodiment of the present invention.

Briefly, cushioning device 13 comprises a pair of relatively shiftable members interposed between platen 11 and support 12 of the press and in the present embodiment, the non-movable portion of the cushioning device is secured to the support 12. Normally, the movable portion of cushioning device 13 is resiliently biased to an elevated position; however, when platen 11 descends and exerts a predetermined force thereon, this portion will be forced downwardly by the moving platen to prevent the latter from exerting more than the predetermined force.

When the platen 11 reaches the end of its stroke and begins to return toward its upper position, the movable portion of the cushioning device will move upwardly with the platen, keeping the force constant, until the cushioning device reaches its elevated position and stops. The platen 11 will then continue its upward movement alone until it reaches its upper stroke limit. Although not shown, the usual dies or other material working devices will normally be positioned between the platen 11 and the cushioning device 13.

As best seen in Figure 2, cushioning device 13 comprises a post-like member 14 whose lower end is secured to support 12 of the press by suitable bolts 15 or the like. For a purpose to become evident, the upper end of post 1 is formed to provide a piston 16. Post 14 is provided with a cavity 17 which provides a sump for containing a quantity of oil or other lubricant. A cylinder member 18 is carried by post 14 and has a bore 19' in which piston 16 is slidable. The upper end of bore 19 is closed by a wall 20' to provide a chamber 21 for containing a compressible fluid such as air. In the present embodiment and for reasons to be disclosed, chamber 21 is in communication with a standpipe 22 which projects above the level of the lubricant in the sump, and which leads to an external surge tank 23.

Means are provided for sealing the operating clearance between piston 16 and bore 19, which clearance has been exaggerated in the drawings. Such means presently comprises a plurality of axially spaced annular sealing mem ber which may take the form of conventional U-shaped packing rings. In the present embodiment, the upper end of piston 16 carries sealing members 24, 25 secured to the piston by a suitable retaining ring 26. Spaced from sealing member 25 is a sealing member 27 which is carried by the cylinder member 18 and held in place by a retaining ring 28 which is secured to the cylinder memher by any suitable means, and which forms an extension thereof. In the position of parts shown, the lower end of retaining ring 28 is provided with an inwardly directed shoulder 29 which engages with a shoulder 30 on the post 14 to limit upward movement of the cylinder member relative to the post.

A conduit 3ll is in communication with the space between sealing members 25, 27 and conduit 31 is connected to a conduit 32 whose lower end is immersed in the lubricant in the sump and to a conduit 33 which terminates adjacent sealing member 24. Suitable check valves 34- and 35 are interposed in respective conduits 32, 33 to limit passage of lubricant to the directions indicated by the respective arrows.

For the purpose of indicating the level of lubricant within cavity 17, a conventional sight glass 36 is positioned to one side of the cushioning device. The lower end of the sight glass communicates with the bottom of cavity 17 by means of a conduit 37 while the upper end of the sight glass communicates with the space above the level of the lubricant by means of a conduit 38. A suitable fitting 39 is provided in conduit 38 to permit introduction of additional lubricant.

Operation of the cushioning device will be as follows: Normally, surge tank 23 will be charged with air under a given pressure, such pressure being determined by the desired amount of force to be exerted by the cylinder member 18. Chamber 21 will also be filled with air under the same pressure which exists in the surge tank since the chamber and the tank are in communication with each other through standpipe 22. With chamber 21 filled with air under pressure, cylinder member 18 will be urged to its uppermost position shown in Figure 2 and 3.

Downward movement of platen ll of press 10 will ultimately exert a downward force on cylinder member 18 of the cushioning device. However, downward movement of the cylinder member will not occur until the force exerted by the platen is suflicient to overcome the opposing force exerted by the air under pressure in chamber 21.

When the force exerted by platen 11 is great enough,

cylinder member 18 will be forced downwardly (see Figure 4). Downward movement of the cylinder member will move sealing member 27 away from sealing member 25 and increase the space between such members. With an increase in space (or volume) between these sealing members, the resultant reduction in pressure will draw lubricant from the sump through conduits and and into the space between the sealing members x3, to 112- bricate the latter. Note that check valve will prevent fiow of fluid in a direction from conduit to conduit When platen 11 moves upwardly, the air in chamber 21 will cause cylinder member 13 to return to the position shown in Figures 2 and 3. This movement of the cylinder member will move sealing member 27 toward sealing member 25 and decrease the space between such members. With the decrease in space between the sealing members, lubricant will be forced from the space through conduits fill and 33 to be discharged by the latter on sealing member 24- to effect lubrication thereof. Note that check valve 34 will prevent flow of lubricant in a direction from conduit 31 to conduit 32.

From the foregoing it will be apparent that each time cylinder member 18 moves downwardly, a charge of lubricant will be drawn into the space between sealing members 25', 2'7 and each time the cylinder member moves upwardly, lubricant will be forced out of the space for discharge on to scaling member 24. Obviously, excess lubricant discharged by conduit 33 will flow down the wall of cavity 17 and collect in the bottom to be recirculated.

in view of the foregoing it will be apparent to those skilled in the art that we have accomplished at least the principal object of our invention and it will also be apparent to those skilled in the art that the embodiment herein described may be variously changed and modified, without departing from the spirit of the invention, and that the invention is capable of uses and has advantages not herein specifically described, hence it will be appreciated that the herein disclosed embodiment is illustrative only, and that our invention is not limited thereto.

We claim:

1. A fluid cylinder comprising a cylinder member having a bore in which a piston is slidably disposed and said cylinder member and said piston being arranged for relative reciprocating movement, spaced-apart means for effecting an annular seal between said piston and said bore and comprising first annular sealing means carried by said piston and slidably engaged with said bore and second annular sealin means carried by said cylinder member and slidably engaged with said piston, said first and second means being movable toward and away from each other to contract and expand the space therebetwcen during relative reciprocation of said cylinder member and said piston, and means for utilizin the expansion of the space between said first and second means to draw lubricant into such space to lubricate said annular sealing means.

2. A. fluid cylinder comprising a cylinder member having a bore in which a piston is slidably disposed and said cylinder member and said piston being arranged for relative reciprocating movement, spaced-apart means for effecting an annular seal between said piston and said bore and comprising first annular sealing means carried by said piston and slidably engaged with said bore and sec ond annular sealing means carried by said cylinder member and slidably engaged with said piston, said first and second means being movable toward and away from each other to contract and expand the space therebetween during relative reciprocation of said cylinder member and said piston, and means for utilizing the expansion of the space between said first and second means to draw lubricant into such space to lubricate said annular sealing means and for utilizing the contraction of such space to displace lubricant therefrom.

'5. A fluid cylinder comprising a cylinder member having a bore in which a piston is slidably disposed and said cylinder member and said piston being arranged for relative reciprocating movement, spaced-apart means for effecting an annular seal between said piston and said bore and comprising first annular sealing means carried by said piston and slidably engaged with said bore and second annular sealing means carried by said cylinder member and slidably engaged with said piston, said first and second means being movable toward and away from each other to contract and expand the space therebetween during relative reciprocation of said cylinder member, and said piston, and means for utilizing the expansion of the space between said first and second means to draw lubricant from a source into such space to lubricate said annular sealing means and for utilizing the contraction of such space to displace lubricant therefrom for return to such source.

4. A fiuid cylinder comprising a cylinder member having a bore in which a piston is slidably disposed and said cylinder member and said piston being arranged for relative reciprocating movement, spaced-apart means for effecting any annular seal between said piston and said bore and comprising first annular sealing means carried by said piston and slidably engaged with said bore and second annular sealing means carried by said cylinder member and slidably engaged with said piston, said first and second means being movable toward and away from each other to contract and expand the space therebetween during relative reciprocation of said cylinder and said piston, third annular sealing means for effecting a seal between said piston and said bore at a place spaced from said first and second means, and means for utilizing the expansion of the space between said first and second means to draw lubricant into such space to lubricate said first and second annular sealing means and for utilizing the contraction of such space to displace lubricant therefrom and to said third annular sealing means for lubricating the latter.

5. A fluid cylinder comprising a cylinder member having a bore in which a piston is slidably disposed and said cylinder member and said piston being arranged for relative reciprocating movement, spaced-apart means for efiecting an annular seal between said piston and said bore and comprising first annular sealing means carried by said piston and slidably engaged with said bore and second annular sealing means carried by said cylinder member and slidably engaged with said piston, said first and second means being movable toward and away from each other to contract and expand the space therebetween during relative reciprocation of said cylinder member and said piston, third annular sealing means for effecting a seal between said piston and said bore at a place spaced from said first and second means, conduit means extending from a source of lubricant to the space between said first and second means and extending from such space to adjacent said third means, and valve means for preventing flow of lubricant through said conduit means in a direction from adjacent said third means toward the space between said first and second means and for preventing fiow of lubricant through said conduit means in a direction from such space toward the lubricant source, expansion of the space between said first and second means drawing lubricant into such space through said conduit means to lubricate said first and second means and contraction of such space displacing lubricant therefrom and through said conduit means to said third means for lubricating the latter.

6. A fluid cushioning device for presses and the like comprising a cylinder member having a generally vertically extending bore, a generally vertical post Whose upper end provides a piston slidably fitting with said bore and about which said cylinder member is reciprocable in a generally vertical direction, said piston having a recess extending downwardly from its upper end to provide a sump for storing a quantity of lubricating fiuid, a plurality of vertically spaced annular sealing members each adapted to effect an annular seal between said piston and said bore and comprising an upper sealing member carried by said piston and slidably engaged with said bore, a lower sealing member carried by said cylinder and slidably engaged with said piston, and an intermediate sealing member disposed between said upper and lower sealing members and carried by said piston and slidably engaged with said bore, said lower sealing member being movable with said cylinder member toward and away from said intermediate sealing member during reciprocation of said cylinder member to contract and expand the space therebetween, conduit means extending from the sump provided by said piston to the space between said lower and said intermediate sealing members and extending from such space to adjacent said upper sealing member, and valve means for preventing flow of lubricant through said conduit in a direction from adjacent said upper sealing member toward the space between said lower and said intermediate sealing members and for preventing flow of lubricant through said conduit means in a direction from such space toward the sump provided by said piston, expansion of the space between said lower and said intermediate sealing members drawing lubricant from the sump in said piston into such space through said conduit means to lubricate said lower and said intermediate sealing members and contraction of such space displacing lubricant therefrom and through said conduit means to said upper sealing member for lubricating the latter.

References Cited in the file of this patent UNITED STATES PATENTS 2,752,212 Hedges June 26, 1956

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