US3743340A

US3743340A - Vacuum lifting device

Info

Publication number: US3743340A
Application number: US00220207A
Authority: US
Inventors: F Williamann
Original assignee: GIS AG
Current assignee: GIS AG
Priority date: 1971-02-10
Filing date: 1972-01-24
Publication date: 1973-07-03
Anticipated expiration: 1990-07-03
Also published as: DE2152584B2; FR2124222B1; DE2152584C3; IT947259B; CH526461A; DE2152584A1; FR2124222A1

Abstract

A vacuum lifting device comprising a bellows suspended at its upper end and equipped with a load holding mechanism at its lower end. The upper end of the bellows can be connected through the agency of valve means with a vacuum pump.

Description

United States Patent [191 Williamann July 3, 1973 41 VACUUM Lmmc DEVICE 2,557,260 6/1951 Clark 294/64 R [75] Inventor: Franz Williamann, Schotz,

l I swltzer and Primary Examiner-Evon C. Blunk [73] Assignee: GIS AG, Schotz, Switzerland Assistant Examiner-Johnny D. Cherry 4 AttorneyWemer W. Kleeman [22] Filed: Jan. 24, 1972 21 Appl. No.: 220,207'

[30] Foreign Application Priority Data [57] ABSTRACT Feb. 10, 1971 Switzerland 1942/71 A vacuum lifting device comprising a bellows sus- 52 US. Cl. 294/64 R, 214/650 so pended at its pp end and q p with a load hold- 51 Int. Cl. B664: 1/02 s mwhahism at its lower The upper end of the Y [5 8] Field of Search 294/64 R, 65; bellows F be connected through the agency of Valve 214/1 ET, 650 5c, means with a vacuum pump.

[56] References Cited 6 Claims, 4 Drawing Figures UNITED STATES PATENTS 3,318,468 5/1967 Olson 294/64 R X PATENTEDJUL 3 I915 slmunrd 1 VACUUM LIFTING DEVICE BACKGROUND OF THE INVENTION The present invention broadly relates to material handling equipment and, more particularly, is concerned with a new and improved vacuum lifting device.

The prior art is already familiar with the technique of equipping lifting equipment with suction cup-like vacuum compartments by means of which the load to be hoisted, for instance a plate, can be retained at the lifting equipment. As a general rule lifting of the load, however, is carried out by mechanical, electrical or hydraulically driven means. i

SUMMARY OF THE INVENTION It is a primary objective of the present invention to provide a novel construction of lifting mechanism cornpatible for automation of its operations and wherein, for instance, plate-shaped loads can be quickly and exactly secured, hoisted and again positively lowered and released at the site where they are to be stacked or deposited.

Another and more specific object of the present invention is directed to a new and improved construction of suction lifting device incorporating a bellows suspended at its upper end and provided at its lower end with a load lifting mechanism, a valve mechanism serves to connect the upper region of the bellows with a vacuum pump.

Still a further significant object of the present invention relates to a novel construction of vacuum load lifting device which is relatively simple in design, easy to operate, economical to manufacture, not readily subject to breakdown, and requires a minimum of servicing and maintenance.

Yet a further object of this invention relates to a load lifting device employing suction lifting forces which can be selectively generated for the purpose of hoisting and lowering a load, the suction action possessing sufficient intensity to positively secure the load in raised position, and when it is desired to again release the load for deposit at a given locality such suction force can be quickly and easily released.

Now, in order to implement these and still further objects of the invention, which will become more readily apparent as the description proceeds, the inventive vacuum lifting device is manifested by the features that there is provided a bellows which is suspended'at its upper end and carrying a load holding mechanism at its lower end. A valve member serves to connect the upper end of the bellows with a negative pressure or vacuum pump.

Through the opening and closing of this valve mechanism it is possible to selectively connect and disconnect the bellows with the negative pressure pump. when the bellows is subjected to the action of the suction of the pump and the pressure of the ambient air it collapses, i.e., its lower end is moved towards its upper end. In this way a load held by the load holding mechanism can be raised.

For the purpose of positively lowering the load or the unloaded bellows, i.e., the bellows without load, it is desirable not only to rely upon the more or less prevailing leakiness or untightness which should of course be avoided for reasons of operational efficiency, rather it is advantageous to connect the bellows through the agency of a further valve mechanism with the surrounding air. Both valves may be controlled in such a manner that only one valve mechanism is open when the other is closed or both are simultaneously closed.

Insofar as the load holding mechanism is concerned it is possible in principle to utilize any optional suitable means for securing and retaining the load and which can be mounted at the lower end of the bellows. In contemplation of the previously mentioned objectives such means may be in the form of automatically controlled means, such as electromagnets, actuatable claws and hooks or equivalent constructions.

It has been surprisingly found that a particularly suitable constructional form of load holding mechanism is realized when there is employed. a suction cabinet or box, the lower end of which is open and the upper end of which can be connected through the agency of a valve mechanism with the lower end of the bellows.

The internal vacuum or negative pressure acting at the bellows as well as the external ambient pressure can not only be used for lifting the load, rather also for clamping and holding the load. As should be readily apparent when, on the one hand, the valve mechanism between the bellows and the vacuum pump is open and, on the other hand, the valve mechanism between the bellows and the suction box is open, the suction box applied to the load, for instance a plate to be hoisted, is evacuated. Hence, the load securely adheres to such evacuated suction box, and upon obtaining a sufficient pressure differential between the interior compartment or inside of the bellows and the ambient air, the bellows itself will be upwardly collapsed together and the load adhering to such suction box will be raised.

To lower the thus raised load it is possible to close at least the valve which connects the bellows with the vacuum pump and to appropriately open the valve connecting the bellows with the surrounding air. When this occurs the bellows will be again extended and finally upon attaining pressure equalization the load will be positively released from the suction box or cabinet. in the event it is desired to delay release of the load then it is possible to maintain the valve which connects the suction box with the bellows closed for such length of time until there is reached the point in time where the load should be released.

Continuing, it is here to be mentioned that it has been found to be advantageous to provide a further valve between the suction box and the surrounding air, rendering possible the release of the load independently of the momentarily prevailing pressure differential in the bellows, i.e., the bellows need not be essentially in extended condition.

In this regard it is also advantageous to provide control means permitting actuation of both suction box valves in a manner that only one is open when the other is closed or both are simultaneously closed.

Additionally, it is further advantageous for certain essentially constant load lifing and transport operations to match the control function of all four valves to one another such that raising and lowering of the bellows can occur by simply switching the operation of the valves, both with or without the load, and at the moment of load release to initiate raising of the unloaded bellows.

Various operation cycles and valve operation are possible with the inventive equipment as illustrated by the following:

a. To lower the empty bellows (unloaded) the valve connecting the bellows with the vacuum pump is closed, the valve connecting the bellows with the surrounding air is open, the valve connecting the bellows with the suction box is closed, and the valve connecting the suction box with the surrounding air is closed.

b. Now if the suction box impacts by means of its bottom face or lower opening against the load then the latter will be clamped by vacuum action against the suction box and a negative pressure condition begins to build up within the suction box and bellows, by virtue of which the bellows is finally collapsed, the load being raised while adhering to such suction box.

c. The hoisted load can be horizontally displaced in elevated position, and at the new locality there can occur lowering of the load in that the valve connecting the bellows with the negative pressure pump is closed and at the same time the valve connecting the bellows with the surrounding or ambient air is opened.

In the event release of the load should occur at any point of time during its lowering, then, additionally, the valve connecting the suction box with the surrounding air can be opened, whereby then simultaneously the valve connecting the suction box with the bellows can be closed. Now, if simultaneously the bellows valves are also switched then the empty bellows will be again folded together or collapsed under the action of the suction created by the pump.

As already discussed, it would be possible to operate with separately controllable suction box valves and during the lowering operation to close the valve connecting the bellows with the suction box and to maintain closed the valve connecting the suction box with the surrounding air until the moment of load release.

The simultaneous closing of all four valves can be carried out as an automatic safety operation in the event that upon breakdown of the pump, for instance because of power failure, the danger of dropping of the load exists. Even in the case of a leak arising the load will only be slowly lowered and ejected so that persons who are in danger can, if necessary, rescue themselves.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and objects other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 is a side perspective view of a preferred embodiment of inventive vacuum lifting device prior to lifting of a platform-shaped or plate-shaped load;

FIG. 2 illustrates the load lifting device of FIG. 1 following complete hoisting of a platform-shaped load;

FIG. 3 is a simplified, fragmentary schematic vertical sectional view through the inventive apparatus of FIG. 1 directly prior to lifting of the load; and

FIG. 4 is a circuit diagram of a possible form of electrical control for the vacuum lifting device of FIGS. 1 to 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Describing now the drawings, the exemplary embodiment of vacuum lifting device depictedin FIGS. 1

to 3 will be seen to embody a collapsible bellows 12 connected through the agency of a valve box or cabinet 14 with the housing 16 of a blower arrangement 18 and is conveniently suspended thereat in any suitable manner. At the top of the suction blower housing 16 there is shown a suspension eyelet 20 or equivalent structure by means of which the load lifting device 10 can be connected via the phantom line illustrated chain 22 or the like to the travelling trolley or carriage 24 moving along the rails 26. Instead of using a travelling carriage or trolley 24 it would be possible to use some other form of suspension and travelling support mechanism, such as a crane, fork-lift device or the like.

At the lower end of the bellows 12 there is connected through the agency of a lower valve box 28, similar to the upper valve box 14, the suction box 30. At the lower edge of the suction box 30 there is provided a sealing lip means 32 against which bears, owing to suetion, a load L, for instance a steel plate, as clearly depicted in FIG. 2. The suction box or cabinet 30 raises such load L whereas, as clearly shown in FIGS. 1 and 2 further such loads L remain in the load stack. The suction box 30 could be provided at its lower open end with any suitable load holding means, such as conventional electromagnets, hook means or load grippers, merely schematically referenced at 33.

Now by referring to the detailed internal structure of the equipment as depicted in FIG. 3 there will be recognized therein a valve 34 here shown in the form of a slide valve or gate, this valve 34 communicating the bellows 12 with the blower arrangement 18 during such time as a valve 36 is closed, this valve 36 being capable of connecting the bellows 12 with the surrounding or ambient air. Since generally the valve 34 is only then open when the valve 36 is closed and vice versa, both

valves

34 and 36 are conveniently interconnected by the connecting rod 42. The valve 34 can be actuated through the intermediary of the rod 44 by the electromagnetic relay 46 of the control circuit of FIG. 4, upon actuating the control or main switch 48 (FIGS. 1 and 2), actuation of the valve 34 then being transmitted via the connecting rod 42 to the other valve 36.

The valve 38 which connects the suction box 30 with the interior of the bellows 12 and the valve unit 40 which can connect this suction box 30 with the surrounding air could be conceivably interconnected by a connecting rod with one another, as explained for the

valves

34 and 36 above, and by means of the rod 50 with an electromagnetic relay 52. In that event the

valves

38 and 40 are only opened and closed in opposed relationship. Operation again takes place through the agency of the switch 48 depicted in FIGS. 1 and 2. Through the use of an appropriate control element, for instance a further respective electromagnetic relay respectively at the rod 42 and/or the

rod interconnecting valves

38 and 40, it would be possible to carry out separate operation of the

valve units

34, 36 and 38, 40. Additionally, by omitting the interconnecting valve rods and by providing completely mechaniically independently controllable or movable valves it would be possible to obtain a still further separation of the actuation.

Still, in the exemplary embodiment under consideration, and as best seen by referring to FIG. 3, only the lowermost arranged

valve units

38 and 40 are independently controlled. To that end there is provided a further electromagnetic relay 54 connected by a suitable operating rod 56 with the valve 40 communicating the suction box 30 with the surrounding atmosphere.

In the illustration position of FIG. 3 the apertures or holes 58 and 60 of the

valves

34 and 38, respectively, communicate with the apertures 62 and 64 of the

valves boxes

14 and 28, respectively, whereas the

valves

36 and 40 maintain the

apertures

66 and 68, respectively, of the

valve boxes

14 and 28, respectively, closed. I

The manner in which the

valves

34 and 36, as well as the

valves

38 and 40, are generally controllable through the agency of the switch 48 has already been considered. In the Table given hereinafter there will be indicated in conveniently discernible form a possible mode of operation of the illustrated exemplary embodiment:

Operation Valves 34 36 38 40 Lifting without load open closed closed open Lowering without load closed open closed closed Lifting with load open closed open closed Lowering with load closed open open closed Ejection of load open closed closed open As will be recognized by referring to FIG. 3, stiffening ribs 70 are advantageously provided within the bellows R2 in order to safeguard against laterally pushing together or collapsing of the bellows by virtue of the prevailing vacuum or negative pressure.

Although for purposes of preserving clarity in the i1- lustration the drawings have not illustrated any means for guiding and limiting the length of the bellows, still, at least for more demanding purposes and in the case of greater loads such guides and limiting means would be provided for preventing over-stretching or over extension of the bellows or a lateral canting or tilting of a not completely centrally engaged load. This can be realized, for instance, through the use of a convention scissor guide arrangement.

Such guides could also be equipped with a brake, for instance, of the type which automatically responds to power failure and which prevents lowering of the bellows. In this connection there may be also provided suitable not particularly illustrated holding pawls for preventing undesired lowering of the bellows 12 upon collapse of the suction. Furthermore, stroke-limit switches could be associated with such type guide arrangement.

Although in the drawings there has only been shown a single suction blower arrangement 18 with the drive motor M and the blower or ventilator V operatively associated with the bellows 12, in the case of installations requiring increased lifting capacity it would be possible to connect a number of bellows with a common blower. However this brings with it the primary disadvantage that pressure losses owing to leakiness of the bellows or the suction box impair the efficiency of all of the bellows connected with the same common blower.

For safety reasons it is advantageous to employ not more than one-half of the difference of the ambient or surrounding pressure, i.e., maximum 0.5 atmospheres absolute pressure for hoisting the load. As a general rule it is preferred to use pumps working with approximately 200 cm. water column negative pressure owing to their good conveying or feed performance; in view of the above approximately 100 cm. water column therefore would be available for lifting the load. As a result quite considerable loads can be raised and securely held. Of course, the suction surfaces of the suction box and the cross-sectional surface or area of the bellows would be accommodated to the contemplated lifting function, and for securely holding the load the bellows cross-sectional surface will be advantageously considerably smaller than the suction box suction surface.

Particularly suitable for the purposes of this invention are slide valves of the type illustrated depicted in FIG. 3 which, while possessing increased friction during vacuum operation, nonetheless still cannot be either closed or opened by the momentarily prevailing differential inpressure. This has the advantage that the regulated or set valve position, i.e., open or closed, cannot be changed by the pressure, rather only through positive actuation of the valve, for instance by means of the associated electromagnetic relay.

Now in the schematic representation of FIG. 3 the valve 34 is depicted to possess a considerably larger through-flow cross-section than the valve 36, and similarly the valve 38 possesses a considerably larger throughflow cross-section than the valve 40. This relationship is not absolutely necessary; however it is generally advantageous for the reason that vacuum or suction operations familiarly respond much more sensi tively to throughflow cross-sections than overpressure conditions, and therefore, there should be present as large as possible free flow cross-sections for the

valves

34 and 38. The differences in size of the

valve units

34 and 38 as depicted in FIG. 3 are not shown on an accurate scale and should not be considered as drawn to scale. A larger valve 3% has the advantage that evacuation of the suction box 30 does not trail evacuation of the bellows 12 so that there will not occur collapse of the bellows 12 before there is built-up a sufficient vacuum for holding the load L. r

The valves 36 and 4b which have been schematically illustrated within the

boxes

14 and 30, respectively, in practice would be advantageously externally arranged so that better sealing conditions can be realized. On the other hand, the

valve units

34 and 38 can be appropriately arranged in accordance with the pressure conditions.

The electrical lines or conduits 72 have only been shown in phantom lines in FIGS. 1 and 2. The switch 48 serves as a central control station for the

electromagnetic relays

46, 52 and 54. For automatic operation there could be accommodated a known unit at the region of the blower arrangement 18 instead of the switch 48. At the rail 26 (FIGS. 1 and 2) it would be possible to initiate a horizontal feed movement through the provision of suitable non-illustrated terminal switch elements located at the travelling trolley 24, so that upon reaching a desired horizontal displacement it would be possible to not only interrupt the horizontal feed movement by the use of other non-illustrated terminal switches arranged at the rails 26 of this travelling trolley 24, but furthermore, there could take place control of the

valves

34, 36, 38 and with regard to the vari ous operations bellows which should be carried out.

In this way it is possible to carry out a complete automation of the lifting mechanism by means of the inven tive vacuum lifting device.

As previously discussed, in the event, for instance, it is only desired to utilize the negative pressure or vacuum prevailing within the bellows 12 for lifting purposes, then, the box 30 can be closed at its lower face or end. In such case it would then be possible to provide this box 30 with a hook, and electromagnet or clamps, as schematically indicated at 33, for attachment to the load L.

With the benefit of the foregoing description of the inventive vacuum lifting device 10 as depicted in FIG. 1 3, there will now be considered in conjunction with FIG. 4 an exemplary construction form of control circuitry for use therewith, the operation thereof being considered for a complete exemplary work cycle: Let it be assumed that the vacuum load lifting device is located in a basic or starting position at the left-side of the rail track 26 in a position preparatory for lowering. By switching-in the main switch 80, the blower arrangement and drive 82 (corresponding to blower arrangement 18 and drive M of FIGS. 1 3) are placed into operation. At the same time a pair of holding magnets 84 which are arranged parallel to the blower motor 82 release two locking pawls which have not been particularly illustrated but which, as previously explained, serve the purpose of preventing the suction surface of the suction box 30 from lowering when the blower is switched-out. In the basic position of the arrangement the switch 86 is located in a position where it connects the contact points 88 90. Now if a pulse is applied to the switch 92, then, the coil of the relay 94 is energized and switched-in. Consequently, voltage is applied to the

valves

34, 36 and 38 which causes lowering of the suction surface of the suction box 30 without load. During this lowering movement there is continuously present in the interior of the bellows 12 a negative pressure. If the suction surface of the suction box 30 arrives at the stack of material, i.e., the goods to be transported, then, the previously mentioned negative pressure collapses. Consequently, the switch 96 is switchedin and energizes the relay 98. This relay 98 switches-in and is held by the switch 100 bridging the contacts 102 104. The relay 94 is switched-out and as a result the

valves

34, 36 and 38 are no longer drawing current, bringing about a lifting movement with load.

At the end of this lifting movement the switch 106 is activated, and thus the relay 108 is energized. Also this relay 108 is held via the switch 100 and the contacts 102 104. Owing to switching of the relay 108 the motor relay 110 for the travel to the right of the vacuum lifting device is switched-in. Upon completion of this travel the switch 100 is activated, thus opening the connection between contacts 102 104 and closing the connection between contacts 102 105. As a result the relays 98 and 108 are switched-out. Consequently, travel toward the right is terminated. At the same time the current is conducted by means of the switch 100 and via contact connection 102 105 over the closed contacts 112 114 of the relay 116 to the

valve unit

34, 36. This operation of such valve unit brings about a lowering movement with load. Now if the lowest point of the lowering movement has been reached, then, the switch 118 is actuated. This switch 118 energizes the coil of the relay 116 so that this relay is switched-in. The contacts 112 114 are opened so that the

valve unit

34, 36 no longer draws current. At the same time both of the

valves

38 and 40 are supplied by the relay 116 so that the load can be released and there can begin the lifting movement without load. At the end of the lifting movement the switch 120 is actuated. Owing to this switching function the relay 122 is switched-in which, in turn, again switches in the motor relay 124 for the left-hand travel. At the end of the travel to the left and upon actuation of the switch 86 the relay 122 is switched-out. Consequently, the device is now once more in its basic or starting position for again carrying out this cycle of operations. It now awaits for the reception of a new pulse from the switch 92 with the blower still running in order to carry out a further working cycle. If the main switch is switched-out then the negative pressure in the bellows l2 collapses, since the blower arrangement and drive 82 shuts down. As mentioned above in order to prevent the suction box and its suction surface from falling downwards there are provided the two holding magnets 84 arranged parallel to the blower motor arrangement 82 which open and close, as desired, an associated blocking pawl.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly un derstood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims. Accordingly,

What is claimed is:

1. A negative pressure lifting apparatus comprising a bellows for load handling suspended at its upper end, a suction box at the lower end of said bellows for holding the load, an upper end wall of the bellows, first valve means in said end wall for directly connecting the bellows with the negative pressure pump to raise the load, a lower end wall of the bellows, second valve means in said lower end wall for establishing direct connection of the negative pressure of said bellows with the suction box to attach the load, third valve means in said upper end wall for the direct connection of the bellows with the surrounding air to lower the load, and fourth valve means in said lower end wall for the direct connection of the suction box with the surrounding air to release the load, whereby said suction box is operated directly from the accumulated negative pressure in said bellows, and the negative pressure in said bellows and said suction box may be released independently.

2. The negative pressure lifting device as defined in claim 1, wherein control means are provided in order to alternately open and close the first and third valve means.

3. The negative pressure lifting device according to claim 1 wherein control means are provided in order to alternately open and close the second and fourth valve.

4. The negative pressure-lifting device according to claim 3 wherein additional control means are provided for simultaneously closing the second and fourth valves.

5. The negative pressure-lifting device according to claim 1 wherein a relatively low prressure blower serves as the negative pressure pump and is connected to the upper end of the bellows.

6. The negative pressure lifting device according to claim 1 wherein control means are provided for simultaneously closing all four valves.

I! I I.

Claims

5. The negative pressure-lifting device according to claim 1 wherein a relatively low pressure blower serves as the negative pressure pump and is connected to the upper end of the bellows.