US3608431A

US3608431A - Control system for the ram of vertically disposed fluid pressure cylinders

Info

Publication number: US3608431A
Application number: US841381A
Authority: US
Inventors: William C Pease
Original assignee: Lummus Industries Inc Co
Current assignee: Lummus Industries Inc Co
Priority date: 1969-07-14
Filing date: 1969-07-14
Publication date: 1971-09-28
Anticipated expiration: 1988-09-28

Abstract

A SYSTEM FOR OPERATING FLUID PRESSURE CYLINDERS, PARTICULARLY CYLINDERS POWERED BY COMPRESSIBLE GASES IN WHICH THE CYLINDER IS ARRANGED VERTICALLY SO THAT ON ITS WORKING STROKE THE RAM OF THE CYLINDER MOVES DOWNWARDLY. A CONTROL SYSTEM FOR THE CYLINDER INTERCONNECTS THE ENDS OF THE CYLINDER ON TE DOWNWARD STROKE OF THE RAM SO THAT THE FLUID UNDER PRESSURE IN THE LOWER END AND WHICH HAS BEEN USED TO RAISE THE RAM FLOWS INTO THE UPPER END SO THAT THE RAM FALLS DOWNWARDLY BY GRAVITY. BY THUS INTERCONNECTING THE ENDS OF THE CYLINDER AT THE TIME INDICATED THE RAM MOVES DOWN, ON ITS WORKING STROKE, WITHOUT BEING CONNECTED TO THE SOURCE OF GAS UNDER PRESSURE. FURTHER DETAILS INCLUDE MEANS TO ADMIT GAS UNDER PRESSURE TO THE UPPER END OF THE CYLINDER WHEN THE INTERCONNECTING PROCEDURE IS INSUFFICIENT TO CAUSE THE RAM TO COMPLETE ITS WORKING STROKE.

Description

Sept. 28, 1971 W. C. PEASE Ill CONTROL SYSTEM FOR THE RAM OF VERTICALLY DISPOSED FLUID PRESSURE CYLINDERS 1 l E Z.

a 43 [co/v7. L 52 5/? can) @(rmse) 45 48 dzs m HM m 1 4 -37 g g If 5:1. v5)

/b 3 M & VAL VE) -4 1, lO 4,2 Z9

WM 4 001.. VALVE) I 5 SUPPLY I g 37; [22 -11 /9 k I L W E 34 1 5/ j k za t J i l E SUPPLY Q T Z/ s */7 A?) INVENTOR.

Wi/l/am C Peaseflz Attorneys United States Patent US. Cl. 91-361 3 Claims ABSTRACT OF THE DISCLOSURE A system for operating fluid pressure cylinders, particularly cylinders powered by compressible gases in which the cylinder is arranged vertically so that on its working stroke the ram of the cylinder moves downwardly. A control system for the cylinder interconnects the ends of the cylinder on the downward stroke of the ram so that the fluid under pressure in the lower end and which has been used to raise the ram flows into the upper end so that the ram falls downwardly by gravity. By thus interconnecting the ends of the cylinder at the time indicated the ram moves down, on its working stroke, without being connected to the source of gas under pressure. Further details include means to admit gas under pressure to the upper end of the cylinder when the interconnecting procedure is insufficient to cause the ram to complete its working stroke.

This invention relates to apparatus for conserving the energy required to operate fluid pressure cylinders and is especially directed to a system for operating pneumatic cylinders of the kind having a ram which may be connected to a platen or the like and which is used to compress fibrous material, or to do other useful work.

An object of my invention is to provide, in combination with a vertically disposed fluid pressure operated,

double acting cylinder, control means associated there-'-- with to conserve the energy to operate the cylinder on its working stroke.

A more specific object is to provide a double acting fluid pressure cylinder having a ram which on its working stroke, that is on downward movement of the ram, the bottom end and upper end of the cylinder are connected, whereby, the fluid under pressure in the ram end of the cylinder is transferred to the blind end, whereby the ram moves downwardly by gravity on its working stroke, thus eliminating the necessity of supplying an additional volume of air from the pressure source to the top of the cylinder.

Another object is to provide a control system for a fluid pressure cylinder of the character designated in which, when the working force to be exerted by the ram exceeds that available for interconnecting the ends of the cylinder on the downstroke, includes means further to pressurize the blind end of the cylinder from an outside source of fluid under pressure, thus supplying the additional energy to cause the ram to complete its working stroke.

A further object is to provide apparatus of the character designated in which the total energy required for the working stroke of the cylinder is decreased by the amount of energy conserved due to interconnecting the ends of the cylinder, as aforesaid.

A still further object is to provide a system of the character described which is especially useful for compacting materials such as fibers in an accumulating chamber, for example, a chamber which may be used for baling 3,608,431 Patented Sept. 28, 1971 "ice such fibers and in which the packer plate or the like on the end of the ram contacts the charge of fibers on its downward stroke, packing the charge beneath certain fiber holding mechanisms, the system including means to cause the ram to reverse after the stock is engaged by the holding mechanisms.

Apparatus illustrating features of my invention is shown diagrammatically in the accompanying drawings forming a part of this application in which:

FIG. 1 is a wholly diagrammatic view illustrating a vertically disposed, fluid pressure operated double acting cylinder and showing the control mechanisms and a portion of the electrical controls;

FIG. 2 is a wiring diagram in which the circles therein represent electrical coils of the several solenoid valves, control relay and timer; and

FIG. 3 is a diagrammatic view of a slightly modified cylinder and ram arrangement.

Referring now to the drawings for a better understand-- ing of my invention I show at 10 a conventional form of cylinder having a ram 11 and a piston 12. For the reasons later to appear the cylinder is arranged sub-- stantially vertically so that the force of gravity aids the downward movement of the ram on its working stroke. The ram may carry a platen or pressure plate 13 and there conveniently may be

guide rods

14 and 16 slidably mounted in bearings 17 and 18 to aid in stabilizing the ram and plate. Further, the cylinder is closed by a head 19 at its blind end and the ram of course slides through the other head 21, in fluid tight manner.

As before stated, one of the principal objects of my invention is to save the energy present in the volume of air which has been used to raise the ram to the position shown in FIG. 1, when the ram is programmed to move on its downward, working stroke. To this end I provide a conduit 22 which enters the blind end of the cylinder and a second conduit 23 which enters the ram end. A cross line 24 connects the

conduits

22 and 23 and this line is under control of solenoid operated valve 26.

The

conduits

22 and 23 are further cross connected by a conduit 27 which adjacent its center leads to atmosphere through a connection 28. Between

conduit

22 and 28 is a solenoid operated valve 29. A similar solenoid operated valve 31 is provided between conduit 23 and the exhaust connection 28.

Fluid, for instance, air under pressure, may be supplied to the system through a line 32, and another branch 33 of the same line. The fluid from the source under pressure, not shown, entering

lines

32 and 33 may be under control of

pressure regulators

34 and 36. In line 32 is a solenoid operated valve 37 and in line 33 is a solenoid operated valve 40.

In the line 24 I may provide a throttling valve 38.

Similar throttling valves

39 and 41 may be provided at the places shown.

In order to indicate the abnormal condition of excess pressure in the blind end of the cylinder 10 I may provide a line 42 which leads to a pressure switch PS which in turn actuates a warning device such as a bell 44.

From what has been described, and illustrating the basic operation of my improved system it can be stated that with the parts in the position shown in FIG. 1 it will be understood that all of the valves are closed. When the system is initiated through a certain control later to be described it will be seen as will later appear that valve 26 opens, thereby interconnecting the upper end of the cylinder 12 with the lower end through the

lines

23, 24 and 22. Therefore, with the ram and platen or work plate 13 raised, the air under pressure in the lower end of the cylinder, that is, beneath the piston 12, now moves through the lines and valve 26 just indicated into the top of the cylinder. When it is considered that some of these devices are extremely large, namely that the total weight of the piston 12, ram 11, platen 13 and its associated mechanism may be on the order of six or eight hundred pounds, it will be apparent that the force of gravity is thus available to cause such weight to do a considerable amount of work. With the cylinder ends connected during downward movement of the ram it is not necessary to call on additional air from the source of supply through line 32 nor to vent the lower end of the cylinder. Therefore valve 37 as well as the remaining valves remain closed. When the piston reaches the bottom of its stroke as will later appear fluid is admitted through supply line 33, valve 26 now being closed, so that the ram is again raised, the upper end in this instance being vented through line 22 and valve 29 to atmosphere through line 28.

Referring particularly to FIG. 2, I illustrate the wiring diagram and this includes a cycle control mechanism S which may be a simple electro-mechanical device which operates the control system in a given sequence or at given intervals.

At 43 I show a control relay which controls sets of

contacts

44, 45 and 46. At 47 I diagrammatically illustrate a time delay relay switch which controls sets of contacts 48 and 49.

One of the guide rods, for instance 14, may

control switches

51 and 52, switch 51 being the switch which institutes the downward movement of the ram as will appear and switch 52 being a return switch. Switch 51 has a normally open set of contacts 51a and a normally closed set of contacts 51b. In other words, when rod 14 is out of contact with the arm of switch 51, contacts 51a are open and contacts 511) are closed, and vice versa.

From what has been described it is now possible to explain a complete cycle of operation of my improved apparatus. Starting with the ram in raised position it will be apparent that it has come to this position by virtue of admitting air under pressure to the lower end of the cylinder. Thus, the ram 11 is retracted within the cylinder and the working element 13 on the ram is in raised position. All of the solenoid valves are deenergized, that is closed. In the raised position of the ram the rod 14 which moves with the ram 11 as shown has actuated the

limit switches

51 and 52 thus opening limit switch contacts 51b, closing contacts 51a and closing switch 52. The energization of the cycle control S also energizes relay 43 closing the normally open contacts 44 thereof thereby locking in relay 43 and also energizes and locks in time delay relay 47. The other set of normally open contacts 45 are closed when relay 43 is energized, thus to energize and open valve 26. This connects the upper end of the cylinder to the lower end through the lines 22, valve 26,

lines

24 and 23. The ram and the working plate 13 and other associated mechanism, under the influence of gravity moves downwardly, whereby the fluid which was under pressure and holding the ram raised passes as indicated, the ram moving downwardly without the necessity of supplying any air from the supply source through line 32.

It might be mentioned that in the event that ram encounters no force which its gravity movement cannot overcome the time delay switch 47 does not time out before the rod 14 moves past the arm of switch 52. Of course, in descending the switch 51 is first deactuated but nothing is changed since relay 43 is energized. Upon continued downward movement, assuming that the ram falls downwardly without encountering any more resistance than can be overcome by the force of gravity moving the parts in that direction, when switch 52 is deactuated it opens, deenergizing relay 43 and time delay 47, thus permitting valve 26 to close. Since the limit switch 51 is now deactuated contacts 511) are closed so that when relay 43 deenergizes its normally closed contacts energize

solenoid valves

29 and 40. This pressures the lower end of the cylinder and vents to atmosphere the upper or blind end, allowing the ram and the piston to move upwardly. When limit switch 51 is again actuated contacts 51b open,

deenergizing solenoid valves

29 and 40 and closing them.

In those cases where the ram is used to pack materials in a collecting chamber and where the material is fed into the top of the chamber, beneath the plate 13, as such stock builds up the tramper plate 13 meets increasing resistance to free fall. This resistance builds up and finally stops the descent of the tramper foot before switch 52 is deactuated. Since the timer 47 is energized on every down stroke, when the ram fails to make a complete stroke, downwardly, the timer 47 times out. When this occurs normally closed contacts 48 open, deenergizing the valve 26 and the normally opened contacts 49 close, energizing

valves

31 and 37. This closes the path between the ram end of the cylinder to the cap end and pressurizes the cap or upper end and vents the lower or rod end. This allows the ram to continue downward movement until limit switch 52 is deactuated, thus reversing the ram direction.

From the foregoing it will be seen that I have devised an improved system for operating fluid pressure cylinders in such fashion as to effect a material saving in the energy required to move the rams and pistons of such devices on their working stroke. As a typical example, I have employed my invention to operate the trampers for packing fibers into a charging box, preparatory to baling them. In this apparatus the fibers are fed into the box, from a side thereof, between the bottom of the box and the bottom of the presser plate or tramper 13. The fibers are pressed downwardly and held beneath certain holding means or dogs, with each stroke of the ram. During the initial part of the filling operation gravity only is required to move the ram downwardly and by bypassing the air from the lower end of the cylinder to the top I eliminate the necessity of supplying compressed air to the top. As the fiber builds up, the tramper foot 13 meets increasing resistance and finally, there will be so much fiber beneath the tramper foot 13 that the control rod 14 will not deactuate switch 52. When this happens the timer 47 times out, thus opening valve 37 to supply additional air under pressure In FIG. 3 I show a modification in which the ram 11a of cylinder 10a passes through the upper end of the cylinder rather than the lower end. The working presser plate or platen 13a is offset from the ram as shown. This modification is operated identically with the one previously described, the same control system being employed.

While I have described a timer as part of my improved circuit, it will be seen that other switching devices may be used. However, in practice I have found the use of a timer as described to be entirely practical.

In actual operation and as applied to trampers for baling fibers, I am enabled to save upwardly of fifty percent of the power heretofore employed in operating fluid pressure cylinders of this type. It will be readily apparent that the amount of energy involved is a function of the volume of air or other fiuid to be supplied, as cylinders of this type have heretofore been operated. By eliminating the power required to provide such volume of air during the free fall portion of the operation I effect considerable savings.

My invention has proved to be satisfactory in every way and is extremely practical and easy to install and maintain.

While I have shown my invention in but two forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof.

What is claimed is:

1. In apparatus for packing fibers into a charging box or the like,

(a) a generally vertically disposed pneumatically operated double acting cylinder having a ram reciprocable through one end,

(b) a valve,

(c) a conduit controlled by the valve eflective when said valve is opened to permit air under pressure to pass from beneath the ram to the upper end of the cylinder, whereby the ram is free to move downwardly on its working stroke by gravity,

(d) other valves for admitting air under pressure to the upper and lower ends of the cylinder and for venting the upper and lower ends of the cylinder to atmosphere, and

(e) control means for said valves eifective to reciprocate the ram on its working and return strokes and further effective when the ram fails to make a complete downward working stroke solely by interconnecting the upper and lower ends of the cylinder to admit air under pressure to the upper end thereof, thus to force the ram to complete its working stroke.

2. Apparatus as defined in claim 1 in which said control means includes a limit control effective to energize the valves controlling upward movement of the ram after it completes a full downward working stroke, and a timer effective upon failure of the ram to make a full Working stroke to admit air under pressure to the upper end of the cylinder, thus to force the ram downwardly, whereby said limit control is then eflective to raise the ram by admitting air under pressure to the lower end of the cylinder.

3. In a control system for reciprocating the ram of a vertically disposed fluid pressure cylinder on its working and return strokes,

(a) a source of fluid under pressure,

(b) a conduit interconnecting the upper and lower ends of the cylinder,

(0) a valve in said conduit,

(d) means to open said valve when the ram is in raised position, thereby to admit fluid from the bottom end of the cylinder to the top end thereof, thereby freeing the ram for downward movement by gravity,

(e) time delay control means operable upon failure of the ram to complete a downward stroke due to the ram encountering more resistance to downward movement than the total force exerted by the ram when the ends are interconnected to admit fluid under pressure to the upper end of the cylinder, thereby causing the ram to complete its downward working stroke,

(f) means to admit fluid under pressure to the bottom end of the cylinder thereby to raise the ram, and

(g) means to vent the upper end of the cylinder while the ram is moving upwardly.

References Cited UNITED STATES PATENTS 5,730 8/1848 Hurst 91437 404,528 6/1889 Foster 91437 2,390,119 12/1945 Nisbet et al. 91-437 2,422,362 6/1947 Moore 9l437 2,875,732 3/1959 Hoffmann 91422 PAUL E. MASLOUSKY, Primary Examiner US. Cl. X.R.