US2644306A - Hydraulic power unit for operation of press elements - Google Patents

Description

July 7,1 53 P. L. PAULSEN 2,644

HYDRAULIC POWER UNIT FOR OPERATION OF PRESS ELEMENTS Filed Aug. 28, 1951 2 Sheets-Sheet 1 Fig.2. z

iii 5 Inventor:

5 6 Paul L..Pau.lsen,

, bg His Attorneg.

J y 7, 1953 P. L. PAULSEN 2,644,306

HYDRAULIC POWER UNIT FOR OPERATION PRESS ELEMENTS Filed Aug. 28, 1951 2 Sheets-Sheet 2 I .7 -Ifi-vento1:

v Paul L.. Paul'sen,

His my I Patented July 7, 1953 HYDRAULIC POWER UNIT FOR OPERATION OF PRESS ELEMENTS Paul L. Paulsen, Bridgeport, Conn, assignor to General Electric Company,

New York' a corporation of Application August 28, 1951, Serial No. 244,042

1 Claim.

This invention relates to an improved hydraulic power system for operating in timed relationship mutually cooperating press elements'such as the elements employed in domestic flatplate ironing machines.

It is the object of the invention to provide an improved valve construction for the hydraulic power system which will insure proper operation without the maintenance of close tolerances.

In carrying out my invention I provide an hydraulic press actuating mechanism including a main cylinder having combined piston and hydraulic pressure generation means, a second or auxiliary cylinder, and a main conduit through which fluid under pressure flows from the first to the second cylinder to exert pressure against a piston therein. The respective pistons are mechanically connected to work devices to operate the same. In an ironing machine,the combined piston and pressure generator may be attached to the lower pressing element or buck, and the piston in the second cylinder arranged to operate a pivotally mounted arm on which the upper pressing element or shoe is mounted. Means are provided to return each piston to a home position in which the buck and shoe are retracted. In such position, a valve comprising the discharge from the pressure generator is seated with respect to an outflow port at the base of the cylinder. This port provides the inlet to the aforesaid main conduit. I relate the discharge valve j area and area of the second piston to each other and to the hydraulic pressure generated within the first cylinder so that with the valve seated at the commencement of operation the pressure causes the second piston to move, thus raising the shoe, but is ineffective to raise the buck.

With this arrangement, the operator may grasp V the rising shoe and hold it against further movement even though the hydraulic generator is still operating, and even though the shoe arm is stopped, the buck piston remains stationary because there is not sufficient hydraulic force to unseat its valve. v

I further provide a. supplemental conduit extending between the first and second cylinders; specifically, the conduit communicates with the first cylinder at the upstream side of the valve seat, and with the second cylinder sufficiently upwardly of its wall to be successively closed and reopened by the piston therein as the same approaches completion of its stroke. Then when the shoe arm actuatin piston has completed its travel, fluid under pressure passes through the conduit from the second cylinder to the area below the first cylinder piston, whereupon the buck will rise smoothly and rapidly.

To insure. proper seating of the discharge valve at each return of the buck piston to home position, I provide a novel discharge valve construction comprising a concave plate or cup member attached at its open end to the buck piston head. This platehas a centrally located opening in its lower portion to which is fitted a resilient annular,

grommet having a substantially flat lower surface engageable with the valve seat portion of the cylinder head at the outflow port. The grommet material is sufficiently deformable that an adequate seal can be maintained regardless of irregularities on the cylinder head surface or slight angular misalignment of the buck piston. Moreover the outside diameter of the annular grommet substantially exceeds the diameter of the outflow port so that the discharge valve structure may have a limited freedom of lateral movement relative to the valve seat without breaking the seal.

My invention willbe better understood from the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claim,

In the drawings, Fig 1 is a side elevation, partially in section, of an ironing machine embodying my invention, the pressing position of the buck and shoe being shown in dotted lines; Fig. 2 is a fragmentary rear elevation showing the association of the buck and shoe actuating cylinders, said figure being in section on line Z- 2 of "-Fig. 1; Fig. 3 is a side elevation in section taken through the lower portion 01f the buck cylinder and throughthe shoevcylinder, and particularly showing the fluid passages interconnectingthe buck and shoe cylinders; Fig. 4 is a view similar to Fig. '3 and showing the piston positions at the beginningof the upward stroke of the buck piston; and Fig. 5 is a-perspectiveview of the impeller. rotor. a

Referring now-to Fig. 1, an embodiment of my invention is applied to a typical ironing machine comprising a suitable mainframe or table I, a buck 2 and a shoe 3, said shoe being carried by a substantially U-shaped carriage or arm 4 pivotally supported with respect to the frame as by pintles 5 mounted in bearing lugs 5 at the base of a main hydraulic cylinder 1. A handle 8 extends across shoe 3 and projects forwardly thereof on suitable brackets 9.

metallic pressing surface units (not shown) embedded therein and having suitable thermostatic control. The buck is supported by a framework ll fixed to the end of a piston Within cylinder 1, as later described. The cylinder is suitably supported by a flange structure l2 bolted or otherwise rigidly secured to the frame I.

Fig. 1 shows in full line the ironer in readiness to have the work placed on the padded buck 2. By means later detailed the shoe is brought forwardly and the buck is moved upwardly to their respective dotted line positions, in which the work then on the buck is pressed against the heated shoe for ironing. The respective movements of the buck and shoe are in synchronized relationship, and result from valve operation in the hydraulic power system. By valve control, hydraulic pressure is automatically made effective against the piston in a shoe operating cylinder l3, and then, at substantially the completion of shoe-carriage travel, within the buck operating cylinder 1. Cylinder l is the pressure source; in said cylinder, as shown in Fig. 3, is a fluid pressure generating system including an impeller [4 at the end of a shaft [5 driven by a motor (not shown) arranged within an enclosed piston structure IS. The buck is affixed to the upper end of the piston l6 by the previously noted frame I I. Piston I6 is provided with suitable piston rings l1, [8, the latter being carried by a piston head I9.

Affixed to the underside of the piston head 19, as by suitable screws 20, is a novel valve structure including a concave plate or cup member 2!. This cup member is provided with an opening in the center of its lower portion in which opening a resilient and deformable annular grommet 22, preferably of oil resistant material, is fixed. In a presently preferred form of my invention the grommet 22 is formed with a large outer diameter relative to the diameter of its center opening, and with a substantially fiat and smooth lower surface. The center opening is of a size larger than needed for the pressure generating system to discharge therethrough liquid at a sufficient rate to elevate the shoe carriage piston at the desired speed, as presently described. The opening' in the grommet 22 may be uniform through part of the grommet thickness and then flared outwardly at the upper end, but the minimum or uniform diameter is, of course, controlling as to the rate of fluid flow.

The cylinder 1 has an integral head portion 23 in which is provided a substantially centrally located passage or port 24 communicating with a main conduit 25 which leads to the lower end of the cylinder 13. Since the valve structure carried by the piston i6 is positioned so that the grommet 22 is in general alignment with the port 24, the cylinder head 23, in effect, forms a valve seat 26 at the port 24. The lower surface of the grommet engages the head 23 when the piston is in its lowermost position, thereby completing a closed passageway between the fluid pressure generator and the auxiliary piston l3. Because the grommet is deformable, surface irregularities on the piston head will not prevent the maintaining of an adequate seal. Moreover a limited angular misalignment between the valve structure and the cylinder head surface can be readily accommodated.

It should be noted that, because of the resiliency of the rings I1 and [8, the piston [6 will not be centrally located each time it returns to its lowermost or home position. Consequently the grommet opening will not always be aligned properly with port 24. Consequently the port 24 as well as the grommet opening is made larger than necessary to permit the required rate of fluid flow, so that limited lateral misalignment of these openings will not adversely affect the operation of the machine. Since the outer diameter of the grommet is considerably larger than the diameter of the port 24, such misalignment will not break the seal.

The piston head I9 is clamped between the cup portion 2| of the valve structure and a plate 2'! by the screws 29; the head l9 cooperates with the plate 2'! to provide an impeller chamber. A ball thrust bearing 28 preferably spring mounted as shown supports the end of the impeller shaft IS. The cylinder 1 has a predetermined charge of a suitable liquid, preferably a light oil. The impeller receives the oil through side wall openings 29, and a central opening 38 in the plate 2?, and discharges it through the grommet 22 and the port 24. With the hydraulic unit in the home position shown in Fig. 3, the oil under pressure is discharged directly to the conduit 25 communicating with the cylinder 13.

The pump motor may be energized by closing a switch, not shown, which may be suitably carried in the lower frame structure. It will be observed that so long as the discharge valve remains seated, the driving. force against piston 56 is equal only to the cross-sectional area of the opening in the grommet multiplied by the unit fiuid pressure. Said area is so related to the area of a shoe actuating piston 3! in the auxiliary cylinder and its work load that the unit fiuid pressure is insufficient to raise piston 16 but is sufllcient to raise piston 3|, said piston having a much greater area than that presented by the grommet opening. -A piston rod 32 fixed to the piston 31 is pivotally connected to the carriage by a suitable yoke 33 as shown in Figs. 1 and 2.

It is, of course, apparent that the operation of the shoe may be stopped at any midposition by merely deenergizing the motor. However, it has been found that under emergency conditions the operator may forget to operate the switch and will instinctively push against the shoe handle 8 to hold the shoe against further movement. In this circumstance the operator may stop the shoe 3 in midfiight, the leverage provided by the shoe carriage 4 being such that the operator may easily oppose the force of piston 3|.

At the completion of travel of the shoe and carriage, as defined by the engagement of carriage 4 with an abutment 34 on the main frame, oil pressure will become available against the effective area of the buck piston head, in a manner explained hereinafter, to lift the piston I6 and the thereon carried buck sufficiently to unseat the valve. As the discharge valve unseats, oil pressure then acts directly against the full area of the piston head with resultant generation of full ironing pressure against the previously positioned shoe 3.

Upon deenergization of the driving motor the rotation of the impeller will immediately cease and the buck piston Will move downwardly under force of gravity assisted by springs 35 and 36 affixed to a pair of cars 31 on the buck frame and to pintles 5 on the main cylinder, as shown in Figs. 1 and 2.

The shoe arm 4 is urged into clockwise rotation of Fig. l by means of a coil spring 38 disposed within the cylinder l3. Spring 38 is maintained in position by confinement between the upper end of the cylinder 13 and-'thepiston 3! as shown in Fig. 3. It is, of course, compressed during the entire movement of the piston. When oil pressuregeneration ceases, the recoil of the spring 38 urges the piston 35 sharply downwardly in its cylinder is, rotating thearm i rapidly away from ironing position. Oil returns to the cylinder 1 above the piston head through channels 39 between the impeller blades as seen in Fig. 5, and the variously disposed piston head and pump casing openings previously described.

Since it is desirable to have the shoe approach ironing position relatively slowly and to return to home position relatively rapidly, I have shown my invention in connection with a supplemental valve system such as that disclosed in the copending application of Robert J. Parsons, S. N. 113,762, filed September 2, 1949, now issued as Patent No. 2,591,464 for Hydraulic Power Unit for Presses and the Like and assigned to the General Electric Company, assignee of the present application. This supplemental system comprises a body member it disposed beneath the grommet opening and within the passage 2d, and having a body passage ll within which freely operates a ball valve 42. The valve body 4!] has two ports 33 and M respectively communicating with conduit 25 above and below the ball valve seat. As appears in Fig. 4, oil discharging through the grommet opening seats the ball valve and thus may enter conduit 25 only through port 43. On the return stroke of piston 3!, at which time it will be understood that pressure generation has ceased in cylinder '5, said piston pumps the oil back through the conduit 25 and into port 4 3, unseating the ball valve, whereupon both ports 43 and 54 are open to provide a relatively large flow path through which oil may return to cylinder i. Ball valve 42 may be retained within the body member in any convenient manner, as by a ported cover plate 48a.

In order to clearly illustrate a probable use of my invention I have disclosed a hydraulic system interconnecting the cylinders 'l' and I3 supplementary to the main passage25. The interconnecting system is generally similar to that disclosed in the copending application of Robert E. Sheahan, S. N. 108,837, filed August 5, 1949, now Patent No. 2,602,246, for Hydraulic Power System. for Synchronous Operation of Press Elements, and assigned to the General Electric Company, assignee of the present application.

This arrangement insures that the work de vices operate in properly timed sequence, and i provide a positive safety element in the event that the work device of piston 31 is held against operation. It comprises a flow passage 45 opening into the chamber below the piston head I 9 at a port 46 and into cylinder [3 at a port 41. A topmost port 58 which, as is evident in Fig. 4, is above the maximum point of travel of the piston 35, provides a vent passage to prevent compression of air within cylinder id as the piston rises, and through which may return to cylinder 1 oil which may have leaked into the cylinder is above the piston. The port 47 is positioned with respect to the piston 31 and its upper limit of work travel so that near said upper limit it is covered by the piston, and at the upper limit, it is either wholly or in substantial partuncovered. It has previously been noted that the piston 34 rises in advance of the piston it because, with the discharge valve in seated position, the area of piston 3! is so much greater than the projected area of the gamma opening in'the discharge that the reaction pressure of the fluid against said areais 'insufiicient to move the piston 16. Piston 3! is moved, whereas piston it remains in home position. The passage c5 and its ports communicating between cylinders l and 13, provide a low resistance path in theevent of leakage at the grommet 22 suflicient' to cause oil to how into the space below the piston head I9. Therefore, even under persistent leakage conditions pressure will not build up below the piston head sufiiciently to thrust the piston assembly upwardly. Any such. leakage would be small when using my improved valve construction and would not rob the cylinder :3 of its actuating pressure. Most of the oil which enters the cylinder l3 above the piston 3! will be returned to the main cylinder I through the port 48 as the piston 3| reaches its uppermost position.

The passage 45 serves to actuate the buck piston it as the shoe piston 3! reaches the upper limit of its stroke. Near the end of travel of piston 3!, at which time the discharge valve would not yet have unseated, oil under pressure will flow from cylinder l3 below the piston 3| through the passages 47, 45, and 46 into cylinder '1 below the piston head where suflicient pressure would then become available to unseat the discharge valve, following which lift of the buck piston l6 would proceed as previously described. In Fig. 4 the arrows indicatin thedirection of oil movement in the cylinder l3 show the movement as it is immediately after the port ET is uncovered, and before the piston I6 has begun its upward travel. It should be understood that in the position shown, with the buck piston slightly elevated, the oil in the auxiliary cylinder would be in a sub stantially static condition.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not Wish to be limited thereto since many modifications may be made; and I therefore contemplate by the appended claim to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

In an ironing machine of the type having a pivotally mounted carriage supporting a heated shoe for movement into and out of register with a buck, hydraulic power means for automatically operating said shoe and buck in sequence for a pressing operation therebetween comprising a main cylinder, a buck piston within said main cylinder and including a power operated pump, a second cylinder, a carriage piston movable within said second cylinder and biased to a posi-- tion holding the shoe away from the buck, a valve seat in said main cylinder downstream of said buck piston presenting a flat surface of substantial area, a passageway of given diameter extending from within said main cylinder centrally through said valve seat to said second cylinder, a valve carried by said buck piston cooperable with said valve seat, said valve comprising a centrally apertured cup member fixed to said piston to receive said pump discharge and an annular resilient member mounted within said central aperture, said resilient member having an orifice of diameter less than said given diameter of said passageway and normally coaxially located with respect thereto and a flat surface adapted to overlie the corresponding surface of said valve seat, and means resiliently biasing said buck piston to a retracted position in which said piston carriedvalve is seated on said valve seat, whereby References Cited in the like of this patent fluid pressure generated by said pun np is efi ective UNITED STATES PATENTS first to drive sald carriage piston within said second cylinder and upon restraint of saidcarriage Number Name Date to unseat said valve and drive said buck piston 5 Hlfner 1929 said main cylinder 2,057,624 Burkhart Oct. 13, 1936 2,117,389 Yoder May 1"], 1938 PAUL PAULSEN 2,591,464 Parsons Apr. 1, 1952

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