US2684659A

US2684659A - Antijet director for lifting devices

Info

Publication number: US2684659A
Application number: US144833A
Authority: US
Inventors: Ackerman Frank
Original assignee: Curtis Manufacturing Co Inc
Current assignee: Curtis Manufacturing Co Inc
Priority date: 1950-02-17
Filing date: 1950-02-17
Publication date: 1954-07-27
Anticipated expiration: 1971-07-27

Description

July 27, 1954 F, ACKERMAN ANTIJET DIRECTOR FOR LIFTING DEVICES 2 Sheets-Sheet 2 Filed Feb. 17, 1950 JNVENTOR ra/1k Ackerman ATTO NEY Patented July 27, 1954 ANTIJET DIRECTOR FOR LIFTING DEVICES Frank Ackerman, Clayton, Mm, assignor to Curtis Manufacturing Company, St. Louis, Mo., a corporation of Missouri Application February 17, 1950, Serial No. 144,833

Claims.

1 This invention relates to improvements in lifting devices. More particularly this invention relates to improvements in lifting devices that use hydraulic fluid and are actuated by pneumatic pressure.

It is therefore an object of the present invention to provide an improved lifting device that uses hydraulic fluid and is actuated by pneumatic pressure.

Lifting devices that use hydraulic fluid and are actuated by pneumatic pressure customarily include stationary cylinders that slidably support hollow plungers. The hollow plungers customarily have openings in the bottoms thereof; such openings receiving upwardly-extending conduits for pneumatic fluid and also serving as orifices for the passage of hydraulic fluid. A charge of oil is customarily introduced into the hollow plunger of such a lifting device, and that oil will occupy most of the volum of the hollow plunger and the cylinder of the lifting device. To cause the hollow plunger to move upwardly it is only necessary to introduce compressed-air into the hollow plunger, by means of them:- warolly-extending conduit; that compressed air acting to force that plunger to move upwardly. The opening in the bottom of the plunger will be large enough to permit that bottom to pass easily through the oil; that oil occupying about the same position in the cylinder whether the plunger is in its upper or lower position, but being below rather than. within the hollow plunger when the plunger is in its upper position. The level of the oil in the cylinder will actually move downwardly a short distance as the plunger moves upwardly; solely to the movement of the oil into the space initially occupied by the walls of the hollow plunger, and that change of level will be quite small. The amount of oil initially charged into the hollow plunger and the length of travel of that plunger are such that when that plunger is in its upper position, the bottom of that plunger will be disposed several inches below the level of the oil in the lifting device. As long as the air pressure is maintained within the plunger, that plunger will remain in its upper position; but when that pressure is released, as by permitting the air to escape through the upwardly-extending conduit, theplunger will move downwardly in response to gravitational forces. As the plunger -moves downwardly, the opening in the bottom thereof will permit that bottom to pass through the oil; most of that oil passing once again into the hollow plunger. The oil will coact with the opening in the bottom of the plunger to probut that change of level will be due vide steady and smooth raising and lowering of the plunger.

Liftin devices of this type have been in use for many years and have worked quite well. However, it has been noticed that appreciable quantities of oil are lost even though all of the joints of the lifting devices are fluid-tight; that oil escaping in the form of a mist with the air that is exhausted from the upwardly-extending conduit as the plunger is lowered. While the rate at which the oil is lost is not very rapid, the loss of oil is very objectionable because the mist will stain objects that it touches, the mist momentarily colors the air adjacent the lifting device and gives that air a strong odor of 01-, the mist causes small pools of oil to form, and the loss of oil requires replenishment of the oil in the plunger.

For over twenty years efforts have been made to prevent this loss of oil, but those efforts have been uniforml unsuccessful. Those efforts were predicated upon the theory that the compressed air, which entered the plunger through the upwardly-extending conduit, would strike the surface of the oil with such force that some of the air and some of the oil would become intimately intermingled and form a mist; that mist exhausting with the pneumatic fluid through the upwardly-extending conduit when the plunger moved to its lower position. Proceeding on the basis of this theory, a large number of devices were proposed and used to reduce the force with which the compressed air struck the surface of the oil; and while those devices couldreduce the force with which th compressed air struck the oil, those devices could not stop the loss ofoil. Th present invention, on the other hand, completely stops the loss of oil from lifting devices, and it does so by providing a construction which is predicated upon a new and different theory. According to that theory, the oil mist is not formed by the forcible striking of the oil by the incoming compressed air; instead, that oil mist is formed by the jetting of oil-upwardly into the plunger as the plunger begins to move to its. lower position. Immediately prior to the release of the compressed air from the plunger, the pressures above and below the bottom of the plunger are equal; those pressures usually being in excess of one hundred pound per square inch. Immediately after the compressed air is released, the pressure above the bottom of the plunger is considerably less than the pressure below that bottom; and as a result, some of the oil below the bottom of plunger jets axially upwardly through the opening in that bottom and forces its way through the oil overlying the bottom of the plunger to form a small fountain of oil in the air-filled upper part of the plunger. The oil in this small fountain will be slowed down by gravitational and wind resistance forces and will eventually fall back to the bottom of the plunger; but in its upward rush, its hesitation at the moment before it begins to fall back, and in its movement downward toward the bottom of the plunger, the oil of the fountain can form a spray or mist which is carried out with air exhausting from the plunger through the upwardly-extending conduit. The greatest part of the oil in the fountain will fall back to the bottom of the plunger and not be lost, but an appreciable amount of that oil will be turned into the oil mist and cause serious dirhculties. The present invention avoids the creation of the oil mist, and the consequent loss of oil, by preventing the jetting of oil in the plungers of lifting devices. It is therefore an object of the present invention to provide a lifting device which prevents the jetting of oil in the plungers of lifting devices.

The present invention does this by providing an oil-directing element adjacent the opening in the bottom of the plunger of the lifting device. Such an element will intercept the oil attempting to jet through that opening, and will direct virtually all of that oil transversely of the plunger; that oil entering and being slowed down by the pool of oil at the bottom of the plunger. With such an oil-directing element, a fountain of oil cannot occur, and thus an oil mist can not form. It is therefore an object of the present invention to provide an oil-directing element adjacent the opening in the bottom of the plunger of a lifting device to intercept oil attempting to jet through that opening and to direct that oil transversely of that plunger.

To intercept the oil attempting to jet through the opening in the bottom of the plunger, the oil-directing element must closely surround the upwardly-extending conduit and must overlie the opening in the bottom of the plunger. If the lower end of the plunger was held against sideways movement, it would be possible to mount the oil-directing element solidly on the bottom of the plunger; however, the lower end of the plunger usually experiences such appreciable sideways movement that a solidly held oil-direct ing element would bend the upwardly-extending conduit. The present invention solves this problem by providing an oil-directing element which has a slidable engagement with the bottom of the plunger; that element tilting as the lower end of the plunger moves sideways and thus avoiding bending of the upwardly-extending conduit. It is therefore an object of the present invention to provide an oil-directing element that closely surrounds the upwardly-extending conduit of a lifting device and has a slidable engagement with the bottom of the plunger of that lifting device.

It has been noted that lifting devices which experience loss of oil, in the form of an oil mist, also experience jerking and bouncing of the plunger as the plunger moves up and down. This jerking and bouncing movement of the plunger is due to the formation of minute bubbles of air in the oil and the accumulation of those air bubbles in the form of air pockets in the cylinder; the air bubbles being caused by aeration of the oil as it formed the oil fountain within the plunger. Any such bouncing or jerking movement is extremely undesirable since it can cause dislodgement of the load carried by the lifting device. All such bouncing or jerking movement is wholly avoided by the present invention, since the present invention avoids the formation of oil fountains in the lifting devices.

Other and further objects and advantages of the present invention should become apparent from an examination of the drawing and acoompanying description.

In the drawing and accompanying description some embodiments of the present invention are shown and described but it is to be understood that the drawing and accompanying description are for the purpose of illustration only and do not limit the invention and that the invention will be defined by the appended claims.

In the drawing Fig. 1 is a sectional View of a lifting device that embodies the principles and teachings of the present invention,

Fig. 2 is a larger sectional view of the oil directing element used in the lifting device of Fig. 1,

Fig. 3 is a plan view of a motion-limiting support for the oil-directing element shown in Figs. 1 and 2,

Fig. 4 is a large cross-sectional view of another oil-directing element provided by the present invention, and

Fig. 5 is a plan view of the oil-directing ele ment shown in Fig. 4.

Referring to the drawing in detail, the numeral H3 denotes the lower part of the cylinder of a lifting device which uses hydraulic fluid and is actuated by pneumatic pressure. The upper part of that cylinder is denoted by the numeral 62; and the upper and lower parts of the cylinder are integrally secured together, as by welding. A guide bearing It is inserted within the upper end of the cylinder of the lifting device, and that guide bearing is locked in place within the cylinder by a threaded ring 15. The threaded ring l5 also acts as a support for the packing iii. A packing gland I! is disposed in the upper end of the cylinder above the packing I6, and that gland holds that packing in position.

A plunger 18 is disposed within and is guided by the inserted guide bearing [4, and that plunger is air-tight except for an opening 20 in the bottom thereof. That portion of the bottom of plunger 18 which defines the opening 20 is made to form a spherical seat, and that seat releasably receives an oil-directing element or oil director 22. This director is carried by the plunger l8, and it has a spherical surface 25 at the lower end thereof that selectively engages the seat, on the bottom of the plunger. When the spherical surface 2'0 on the director 22 engages the spherical seat on the bottom of the plunger, oil will be unable to flow between that surface and that seat. As a result, the director 22 also acts as a valve. The. director 22 is hollow and it has a conical upper end. Openings 24 are provided in the sides of the director 22, and those openings have their axes perpendicular to the axis of the plunger 58. The openings 24 are suiiiciently small to limit the flow of oil through them.

A recess 28 is formed. in the under surface of the bottom of the plunger i8, and that recess is concentric with the seat in that bottom. A retaining plate 30 is disposed adjacent that recess, and that plate partially closes the lower end of that recess. The retaining plate 39 is of generally triangular configuration and it has a central opening 32 therethrough. The opening 32 underlies the director 22, but it is small enough that the director 22 cannot pass through it; instead, the bottom of the director 22 can rest upon the retaining plate 30. I

An upwardly-extending conduit 34 is directed axially of the plunger I8, and that tube extends upwardly through'the plunger to a point adjacent the top of that plunger when the plunger is in lowered position. The tube 34 extends through the opening 32 of the retainer 30, through the hollow portion of the director 22, and through the closely-fitting opening 21 in the top of that director 22. The opening 27 is large enough to permit frictionless movement of the director 22 relative to the tube 34, but is small enough to prevent appreciable jetting of oil through that opening. The lower end of the conduit 34 is denoted by the numeral 36, and it extends to a female fitting 38 which can be connected to a source of compressed air.

A quantity of oil is initially charged into the plunger I8, through the opening I9, and that oil will fill the greater part of the volume of the plunger and cylinder. An air bleed, not shown, will be provided for the cylinder to permit removal of all air below the packing IS. The amount of oil charged into the plunger and cylinder will be great enoughto insure that a pool of oil will always surround and cover the director 22, even when the plunger is in its upper position. To raise the plunger, compressed air is forced through conduit 34 to a point immediately adjacent the top of the plunger I 8. This air will act upon the oil in the plunger and will act to force the plunger I8. to move upwardly. As the plunger moves upwardly, the opening 20 in the bottom of the plunger will permit that bottom to move through the oil; oil passing from above to below the bottom of the plunger by passing through the openings 24 and hollow portion of the director 22 or through the gap between the surface 26 of the director 22 and the seat on the bottom of plunger I8. The director 22 will normally be in a position where it can rest on the retainer 30, as shown in Fig. l; and when the director 22 is in that position-a relatively large path for oil will be provided between the seat on the bottom of plunger I8 and the surface 26 on the director 22. The combined area of that path and the openings 24 make it possible for plunger to move upwardly through the oil with ease.

The compressed air will be permitted to flow into the plunger I8 until the stops 2I on the lower end of the plunger engage the bottom of the guide bearing I4. At such time, the level of the oil in the lifting device will be several inches above the top of the director 22; the supply of oil initially charged into the plunger I8 being great enough to take care of this. Theplunger I8 can be held in its upper position as long as desired, by the compressed air.

When the plunger I8 is to be lowered, the compressed air is permitted to escape through the conduit 34 to a venting valve, not shown, that is located externally of the cylinder. As the air escapes from the plunger I8 and into pipe 34, the plunger will begin to descend. There will be a tendency for that oil to jet upwardly through the opening 20 and to form a fountain of oil in the plunger I8, but. that tendency will be completely overcome by the director 22. That director will respond to the pressure differential above and below the bottom of the plunger I8 to move upwardly until its surface 26 engages the seat on the bottom of the plunger; and in doing so, that director will force'all oil entering the 6. plunger I8 to pass through the openings 24 of the director 22. The axes of those openings are transverse to the axis of the plunger I8; and when the 011 issues from openings I 4, it will enter the pool of oil constantly maintained about the director 22. The lower portions of that oil will experience considerable agitation, but the surface of that pool will remain relatively quiet; and there will not be a fountain of oil in the plunger I8. This is in sharp contrast to prior liftin devices, wherein the oil jetted into the plunger and formed a mist-creating oil fountain.

When the plunger I8 reaches the bottom of its stroke, the director 22 will once again come to rest upon the retainer 38. At such time, there will again be a large opening between the surface 26 of the director 22 and the seat on the plunger to permit flow of oil as the plunger I8 moves through the oil. As a result, there will be but little resistance to the upward movement of the plunger I 8.

The director 22 is provided with a conical top to facilitate the assembly of the plunger and cylinder of the lifting device. All that need be done in assembling the plunger and cylinder is to direct the conduit 34 along the axis of the cylinder, and then telescope the plunger within the cylinder. The conical top of the director will automatically guide the upper end of the conduit 34 to and into the opening 21; whereupon the plunger I8 can be telescoped fully within the cylinder.

The director 22 is made rather long, and it is given the spherical surface 26 to enable that director to tilt relative to the bottom of the plunger I8. This is necessary to avoid bending the conduit 34 as the lowerv end of the plunger experiences sideways movement. In the absence of a sliding engagement between the director 22 and the plunger I8, any sideways movement of the bottom of the plunger in excess of the small clearance between opening 27 and conduit 34 would force the director to bend the conduit 34. With the spherical surface 26 and the spherical configuration of the seat in the bottom of plunger I8, and with the long movement arm provided between opening 21 and surface 26, the director 22 is enabled to tilt relative to the plunger and avoid bending of conduit 34 when the lower end of the plunger moves sideways.

In Figs. 4 and 5, an alternate form of the present invention is shown and described. A plunger 40, generally comparable to the plunger I8 of Figs. 1 and 2, is provided. That plunger will be guided and held by a cylinder comparable to the cylinder shown in Figs. 1 and 2. An oil director 42 will be supported by the bottom of the plunger 40 and it will be disposed adjacent an opening 43 in the bottom of that plunger. The oil director 42 has four spaced feet 44 that engage the bottom of the plunger 40 and space the director 42 above that bottom. The spaces between the legs 44 will act as openings through which oil can pass as the plunger moves through the oil. The top of the director 42 has an opening 45 therethrough, and that opening will closely encircle the conduit 46 which extends upwardly into the plunger 40. The conduit 46 -will be largely comparable to the conduit 34. The clearance between the director 42 and the conduit 45 will be so small that oil tending to jet through that gap will be largely intercepted. The director 42 will have a conical surface at the upper end of the interior thereof. a

A plate 48 is disposed above the director42, and

that plate is held in position by the conjoint action of sleeves G and bolts 52; the bolts 52 extending through the sleeves 50 and seating in the bottom of the plunger 40. The plate ts will ccact with the inlet tube 46 to'hold the director 42 against movement away from the tube 45 while permitting a slightaxial movement of the director 42 relative to the bottom of the plunger 43.

A valve 56 is disposed below the plunger 40, and that valve loosely encircles the conduit 45. That valve is held in assembled relation with the bottom of the plunger 49 by bolts 54; the bolts 54 extending into and seating within the bottom of that plunger. The bolts 54 permit the valve 56 to lie a short distance below the bottom of the plunger 40 or to move upwardly into contact with that bottom. When lying below and out of contact with the bottom of the plunger 46, the valve 46 permits relatively unimpeded move-- ment of oil through opening 13; but when in contact with the bottom of plunger lit, the valve 45 will obstruct the flow of oil through opening 43.

The operation of the lifting device shown in Figs. 4 and 5 is generally comparable to the operaticn of the lifting device shown in Figs. 1 and 2; the difference being that the director 22 of Figs. 1 and 2 performs two vital functions while the director 32 of Figs. 4 and 5 performs just one function. The director 42 and the valve will normally be in their lower positions, as shown in Fig. 4; and at such time oil can flow freely through the opening 43. As air is pumped in \vardly through the pipe 45, the plunger at will move upwardly; and oil will move inwardly through the spaces between the legs 44 of director 62, downwardly through the opening 133, and. either through the central opening of valve or through the space between the valve 55 and the bottom of the plunger 40. The quantity of oil initially charged into the plunger Gil and its surrounding cylinder will be great enough that the director 42 will always be surrounded and covered by a pool of oil when the plunger is in its upper position.

Whenever the plunger 40 starts downwardly, the pressure differential above and below the plunger will force the valve 56 into intimate contact with the bottom of the plunger 48. There after, oil entering that valve must pass through the central opening of that valve; that opening tending to restrict the rate at which the plunger it can move downwardly. Oil passing upwardly through the central opening of the valve 56 will pass through the opening 43. That oil will be unable to jet into the plunger 40 because the opening 45 encircles the tube 45 so closely. The director s2 will pass outwardly through the openings formed by legs 44 and into the pool of oil surrounding and covering that director. As a result no fountain of oil will occur, and no oil mist will be created.

The director 22 of Figs. 1 and 2, and the director 12 of Fig. 4 are shown as they would be used with lifting devices wherein air is introduced into the plungers; those plungers constituting movable reservoirs. Those directors could be used -with lifting devices wherein only hydraulic fluids are introduced into the plungers as by providing them with closed tops and positioning them adjacent the oil inlet of the fixed reservoirs of such lifting devices. Minimization or prevention of entrainment of the oil in the air used in those lifting devices would result.

The directors shown in the drawing perform the dual functions of intercepting any oil tending to jet through the opening in the bottom of the plunger and of directing that oil into the pool of oil surrounding and immersing that director. However, if desired, either of the directors in the drawing could be replaced by two directors that each perform only one of the said functions.

Where these various directors have been applied to lifting devices, considerable savings in oil have been eifected. The saving is important from the standpoint of the oil that is lost, but it is even more important from the standpoint of avoiding stains caused by the oil mist, avoiding oil pools formed by the oil mist, avoiding pollution of the air adjacent the lifting device, and avoiding jerking and bouncing movement of the plungers.

Whereas several embodiments of the present invention have been shown and described in the drawing and accompanying description it should be apparent to those skilled in the art that various changes may be made in the form of the invention without affecting the scope thereof.

What I claim is:

l. In a lifting device that has a stationary cylinder, a movable plunger slidably disposed within said cylinder, said plunger being hollow, an inlet pipe for pneumatic fluid that extends upwardly into said plunger through an orifice in the bottom of said plunger, and a quantity of hydraulic fluid within said cylinder and said plunger, the improvement which comprises a director that encircles said inlet pipe and is in registry with said orifice, said director having an opening at the top thereof which is so'dimensioned relative to said inlet pipe as to permit movement of said director relative to said inlet pipe but to largely prevent passage of hydraulic fluid between said director and said inlet pipe, said director having a transversely-directed opening therein adjacent the bottom thereof, said director being dimensioned to be immersed in a pool of hydraulic fluid throughout the operation of said lifting device, said director receiving hydraulic fluid from said orifice and limiting further upward movement of said hydraulic fluid and directing said hydraulic fluid through said transversely-directed opening into said pool of hydraulic fluid in said plunger, thereby deterring jetting of said hydraulic fluid.

2. In a lifting device that has a stationary cylinder, a movable plunger slidably disposed within said cylinder, said plunger being hollow, an inlet pipe for pneumatic fluid that extends upwardly into said plunger through an orifice in the bottom of said plunger, and a quantity of hydraulic fluid within said cylinder and said plunger, the improvement which comprises a director that encircles said inlet pipe and is in registry with said orifice, said director having a substantially closed top, said director having an opening that is intermediate the top and bottom thereof and that extends transversely thereof, said director being disposed closely adjacent said orifice, said director receiving hydraulic fluid from said orifice and acting through its substantially closed top to limit further upward movement of said hydraulic fiuid and acting through its said opening to direct said hydraulic fluid into said plunger transversely thereof and thereby deter jetting of said hydraulic fluid.

3. In a lifting device that has a stationary cylinder, a movable plunger slidably disposed within said cylinder, said plunger being hollow, an inlet pipe for pneumatic fluid that extends upwardly into said plunger through an orifice in the bottom of said plunger, and a quantity of hydraulic fluid within said cylinder and said plunger, the improvement which comprises a director that encircles said inlet pipe and has a substantially closed top which largely prevents passage of hydraulic fluid between said inlet pipe and said director, said director being in registry with said orifice, said director having a transverselydirected opening therethrough below said substantially closed top, said director being adapted to receive hydraulic fluid passing through said orifice and limit further upward movement of said hydraulic fiuid and direct said hydraulic fluid through said opening into said plunger and thereby deter jetting of said hydraulic fluid, said director having a surface thereon that is selectively engageable with the bottom of said plunger adjacent said orifice to valve the flow of hydraulic fluid through said orifice, said director moving the said surface thereon into engagement with said bottom of said plunger whenever said plunger moves downwardly, and a retaining plate for said director adjacent said orifice.

4. In a lifting device that has a stationary cylinder, a movable plunger slidably disposed within said cylinder, said plunger being hollow, an inlet pipe for pneumatic fluid that extends upwardly into said plunger through an orifice in the bottom of said plunger, and a quantity of hydraulic fluid within said cylinder and said plunger, the improvement which comprises a director that encircles said inlet pipe and is in registry with said orifice, said director having an opening at the top thereof which is so dimensioned relative to said inlet pipe as to permit movement of said director relative to said inlet pipe but to largely prevent passage of hydraulic fluid between said director and said inlet pipe, said director having an opening that is below the level of the first said opening and that is transverse of said director, a spherical seat on said plunger, and a spherical surface on said director, said spherical seat and surface permitting tilting of said director as the lower end of said plunger moves sideways, said director receiving hydraulic fluid from said orifice and limiting further upward movement of said hydraulic fluid and directing said hydraulic fluid through the second said opening into said plunger.

5. In a lifting device that has a fixed portion, a movable portion, and a quantity of hydraulic fluid that responds to pneumatic pressure to move said movable portion, the improvement which comprises an orifice for the passage of hydraulic fluid, a director that is disposed adjacent to and overlies said orifice, and a retainer for said director, said retainer being spaced from said orifice to permit limited movement of said director between said orifice and said retainer, said director having a fluid-intercepting surface that is substantially in register with said orifice, said director being dimensioned to be immersed in a pool of hydraulic fluid throughout the operation of said lifting device, said director having an opening that is below the level of said surface and is transverse of said director, said director being supported by and moveable with said movable portion, said surface receiving hydraulic fluid from said orifice and said opening conducting said hydraulic fluid into said pool of hydraulic fluid to deter jetting of said hydraulic fluid.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,689,145 Lunati Oct. 23, 1928 1,899,534 Steedman Feb. 28, 1933 2,288,511 Bratz June 30, 1942 2,336,817 Thompson Dec. 14, 1943 FOREIGN PATENTS Number Country Date 446,774 Great Britain May 6, 1936