US2591464A - Hydraulic power unit for presses and the like - Google Patents

Description

P 1952 R. JQPARSONS HYDRAULIC POWER UNIT FOR PRESSES AND THE LIKE Filed Se t. 2, 1949 lnven tor-z Roberft. .J. Parsons,

His Attorney.

Patented Apr. 1, 1952 HYDRAULIC POWER UNIT FOR PRESSES A D THE LIKE Robert J. Parsons, Bridgeport, Conn, assignor to General Electric Company, a corporation of New York Application September 2, 1949, Serial No. 113,762

(Cl. Gil-52) 6 Claims.

This invention relates to an improved hydraulic power unit for the operation of machines in which a plurality of elements are to be brought in synchronism from a home position to an operating position and return.

In particular, my invention is useful in the hydraulic operator forming a part of the apparatus described and claimed in the application of Robert E. Sheahan entitled Hydraulic Power System for Synchronous Operation of Press Elements, Serial No. 108,837, filed August 5, 1949, and assigned to the assignee of the present application. The Sheahan hydraulic unit comprises mutually interconnected cylinders, the piston of each being mechanically connected to an element of a press-i11ustratively a domestic ironing machine-to operate the same. One of said cylinders has a hydraulic pressure generating means contained within its piston, said generating means having a discharge valve which includes a short, relatively small diameter, nozzle. At the completion of an operating cycle, the piston comes to a home position, in which the nozzle occupies a valve seat provided in the base of the cylinder and at the head of a conduit communicating with the second cylinder. The piston of the second cylinder is substantially larger in area than that of the seated valve, and the respective areas are so related one to the other, and to the generated pressure, that with the nozzle valve seated at the commencement of the next operation, the hydraulic pressure generated within the cylinder is effective to move the piston of the second cylinder only. When said piston completes its travel, as determined by suitable stop means, the hydraulic pressure unseats the nozzle valve and fluid pressure becomes effective within the first cylinder, to propel its piston. The timed operation of the first and second pistons is therefore controlled by the sequence in which hydraulic pressure is eifective within the respective cylinders. It will be apparent that such operation requires that the nozzle valve seat accurately at each return to home position, so as to prevent any substantial leakage past the valve and into its associated cylinder.

Among the objects of the present invention are to provide an improved valve construction which will insure the proper seating of the nozzle valve at each return to home position, and to provide means whereby the return stroke of the piston of the second cylinder may be effected at a more rapid rate than its upstroke. As a presently preferred manner of accomplishing these objectives I provide a valve system in which the valve seat member and nozzle valve element have a limited freedom of movement relative to each other, so that as the nozzle valve seeks its seat the seat member will come into proper alignment. Associated with said valve seat I provide a valve in the conduit communicating between the first and second cylinder and effective automatically to increase the flow capacity of said conduit during the return of fluid from the second to the first cylinder.

These and other objectives and advantages will be apparent from the following specification, read in connection with the accompanying drawing in which Fig. 1 is a fragmentary side elevation in partial section showing my improved valve structure applied to a hydraulic pressure generating system and showing the relative position of the parts as the instant pressure fiow commences from the first to the second cylinder. Fig. 2 is an end elevational view of the apparatus; and Fig. 3 is a view similar to Fig. 1 but showing valve action at the commencement of the return of the pistons to home position.

Referring first to Fig. 2 there is shown a hydraulic pressure system arranged for operating an ironing machine such as that shown in the Wardwell, Jr., Patent No. 2,135,266 granted November 1, 1938, for Ironing Press. Applying the general structure of said patent to the present disclosure, a buck I is mounted on a combined piston and pressure generating means 2 operating with a cylinder 3 suitably fixed to the table 4 of the ironing machine. The pressure generating means includes a cylindrical housing 5 within which is a motor (not shown) and a shaft 6 terminating in a pump 1. The structure includes suitably spaced piston rings 8, 9. Through the ports [0 and H, the oil content of the cylinder, represented by the level OIL, enters a pump casing l2 to be discharged therefrom through outflow ports l3. In the Wardwell patent, the oil pressure is immediately effective to drive the piston 2 in the cylinder, and thus to raise the buck. Also in said patent, the shoe or cooperating ironing element is carried by an arm such as the fragmentarily shown arm l4 herein, said arm being pivoted at the bottom of the cylinder 3 as by suitable pivot screws, and by means of a handle provided on the ironer shoe, the latter is .manually positioned above the buck, prior, of course, to the operation thereof. Pursuant to the aforementioned Sheahan application, however, the arm l4 herein is mechanically swung counter-clockwise of Fig. l to its operating position by means of a piston ii in a second cylinder [6, said piston be ing drivingly associated with the arm M by a suitable link ll. After completion of the pressing operation, the operator stops the motor, whereupon suitable spring means such as the spring [8 extending between the cylinder 3 and a collar 20 on the buck aids the return of the piston 2 to home position. Similarly, suitable spring means 2| within the cylinder l6 assists the return of the piston I and its therewith associated shoe I4 to home position.

In the hydraulic system shown herein pump 1 discharges through the ports l3 into a valve structure includin a body plate 23 which terminates in a relatively short, tapered, nozzle valve 24. In the home position of the piston said valve 24 is seated on valve seat 24a so that the entire discharge from pump 1 passes into the conduit 25 communicating with cylinder [6. As is more fully explained in said Sheahan application, the effective area of piston 2 when the valve 24 is properly seatedis much smaller than the area of piston I5, with the result that piston I5 is driven upwardly within its cylinder whereas the piston 2 remains in home position. This condition prevails until the piston i5 is brought to a halt by suitable stop means (not shown), whereupon the pump discharge pressure becomes effective beneath the piston 2 to raise it and its associated buck to operating position. As explained in the Sheahan application, there is provided a passage 26 communicating between cylinder 3 and cyllnder l6, entering the latter at ports 21, 28. It will be observed that at the end of travel of piston l5, as shown in dotted lines in Fig. 1, the port 21 is uncovered by the piston whereupon oil under pressure returns to cylinder 3 through passage 26, to exert pressure against the piston 2. Any oil which may have entered the cylinder l5 above the piston may return to cylinder 3 through a port 30. I

I insure the proper seating of the valve 24 at each return to home position by making the nozzle valve and the valve seat self-aligning; for example, by positioning the valve seat member 24a within a suitable chamber formed in the bottom wall of cylinder 2 so as to have limited movement therein. A cover ring 32 or equivalent completes the confinement of the seat. The tapered wall of the valve seat opening cooperates with the tapered wall of the nozzle valve 24 to provide substantial contact area therewith, and it will be apparent that the reduced diameter end of the nozzle valve 24 acts as a pilot as the valve enters the seat opening, shifting the seat into proper alignment for accurate reception of the nozzle valve. I prefer to make the valve seat 24a the adjustable member rather than the nozzle valve 24 because of the relatively more difficult problem of sealing the slidable contact between the nozzle and the walls of a pocket formed in the body plate 23. A second alternative would comprise making the piston ring flanges of smaller diameter and increasing the depth of the ring slots, so as to give the entire piston lateral play Within the cylinder.

In ironing machines it is desirable to have the shoe approach ironing position relatively slowly to minimize inertia effects and undesirablejarring as the shoe stops in its working position, but to return to home position relatively rapidly. I accordingly provide a supplemental valve system comprising a body member 33 disposed beneath the valve seat member in registry with the opening thereofand having an enlarged body passage 34 within which freely operates a ball valve 35. A suitably ported cover plate 36 is conveniently secured at the entrance to passage 34 by the seat member 24a. The valve body has two passages, 31, 38 respectively communicating with conduit 25 above and below the ball valve seat. Passage 38 and its therewithcommunicating body passage 39 is of substantially larger diameter. As appears in Fig. 1, oil discharging through valve 24 seats the ball valve and thus may enter conduit 25 only through the smaller port 31. On the return stroke of piston l5, at which time it will be understood that pressure generation has ceased in cylinder 3, said piston pumps the oil back through conduit 25 and into passages 38, 39 to unseat the ball valve; see Fig. 3, to provide a relatively large flow path supplementing the passage 31 through which oil'may return to cylinder 3. Oil entering the cylinder will encounter the downwardly driving piston 2 and will thereupon find its way through valve 24, orifices l3 and the several pump housing inlet openings to re-establish substantially the original oil level.

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 claims 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:

1. In a fluid pressure power system, a work device to be operated by fluid pressure, a cylinder, valve means including an annular valve seat member confined within a wall of said cylinder for limited lateral movement therein, a conduit communicating between the downstream side of said valve seat and said work device, a combined piston and fluid pump in said cylinder, said pump having discharge means including a nozzle valve member for cooperation with said valve seat member, means for establishing a home position in which said nozzle valve is seated within said seat member, and means for operating said pump to create fluid pressure for operation of said work device, said combined piston and pump being free to withdraw from said valve seat and expend said pump pressure against itself upon abnormal resistance of said work device to opera tion by said fiuid pressure.

2. In a fluid pressure power system, a work device to be operated by fluid pressure, a cylinder, a conduit communicating between said cylinder and said work device, a combined piston and fluid pump in said cylinder, said pump having discharge means including a nozzle valve member, an annular valve seat member within said cylinder in communication with said conduit, means for adjusting the relative position of said nozzle valve and said valve seat member to insure the seating of said valve thereon, means for urging said cylinder into a home position in which said nozzle valve is seated, and means for operating said pump to create fluid pressure for operation of said work device, said combined piston and pump being free to withdraw from said valve seat and expend said fluid-pressure against itself upon abnormal resistance of said work device to operation by said pressure. p

3. In a fluid pressure power system, a work device to be operated by fluid pressure, a cylinder, a combined piston and fluid pump in said cylinder, said pump having discharge means including a nozzle valve member, an annular valve seat member within a pocket in a wall of said cylinder, said pocket being substantially concentric with the nozzle valve and of larger diameter than said seat member to permit the same to shift its position therein, a cover plate for securin said seat member within said pocket, a conduit extending from the downstream side of said seat member to said work device, means for urging said cylinder into a home position in which said nozzle valve is seated on said member, and means for operating said pump to create fluid pressure for operation of said work device, said combined piston and pump being free to withdraw from said valve seat and expend said fluid pressure against itself upon abnormal resistance of said work device to operation by said pressure.

4. A hydraulic power system for operating a pair of work devices comprising a cylinder having combined piston and hydraulic pressure generating means therein, a second cylinder having a piston therein, each piston being arranged to drive one of said work devices, means for returning each said piston to a home position, means for operating said pressure generator, and means for making the pressure generated thereby temporarily efiective to move the piston of the second cylinder only, comprising a nozzle valve member defining the outlet from said pressure generator, said valve member having an area substantially smaller than the piston in said second cylinder, an annular valve seat member in which said nozzle valve seats when its associated piston is in home position, said nozzle valve and seat member having limited adjustability relative to each other, and a conduit extending between the downstream side of said valve seat member and said second cylinder, whereby with the nozzle valve seated the hydraulic pressure fluid passes directly through said conduit to said second cylinder.

5. In a hydraulic power system for operating a pair of work devices, a cylinder having combined piston and hydraulic pressure generating means therein, a second cylinder having a piston therein, each piston being arranged to drive one of said work devices, means for returning each said piston to a home position, means for operating said pressure generator, a conduit communicating between said cylinders for flow of fluid under pressure from said first to said second cylinder during the work stroke of said second cylinder piston and return to said first cylinder upon return of said second piston to home position, and valve means in said conduit for restricting said flow in one direction relative to flow in the opposite direction, including a valve body member, said body member having a port communicating with said first cylinder and a pair of ports of respectively different flow capacity communicating with said second cylinder, and valve means within said body member arranged to close one of said pair of ports during fiow from said first cylinder and to open said port upon flow through said conduit to said first cylinder.

6. In a hydraulic power system for operating a pair of work devices, a cylinder having combined piston and hydraulic pressure generating means therein, a second cylinder having a piston therein, each piston being arranged to operate one of said work devices, means for returning said pistons to a home position, means for operating said pressure generator, a conduit between said first and second cylinders whereby the pressure generated in the first cylinder may be made available in the second, and valve means in said conduit to ofiier a difierent resistance to flow to said second cylinder than to flow in the opposite direction, comprising a valve body having a chamber communicating with said first cylinder, a plurality of other ports of different flow capacities communicating between said conduit and said chamber, and a ball valve in said chamber responsive to the direction of fluid flow therethrough to block flow through one of said last named ports or to expose said port.

ROBERT J. PARSONS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,135,266 Wardwell Nov. 1, 1938 2,441,358 Johnston May 11, 1948 2,475,304 Barifii July 5, 1949

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