Manhole system

A remotely actuated manhole system is disclosed having a cover that is pivotable relative to a frame secured with a collar on a bulk carrier, the cover being pivotable around a substantially vertical axis between and to open and closed positions. In the closed position covering an opening to a compartment in the bulk carrier, the cover is shiftable vertically between and to locked and unlocked positions by an inflatable seal member below the cover. The manhole system includes catches that prevent over-rotation of the cover from the open position to the closed position, and the catches engage in the locked position by the vertical upward movement of the cover. The inflation of the seal member and the pivoting of the cover are remotely actuated.

FIELD OF THE INVENTION

The invention relates to closure systems and, in particular, to a manhole system for a bulk carrier such as a tank and, more particularly, to a manhole system with a manhole cover positionable over an opening in a bulk carrier and shiftable to lock the manhole cover.

BACKGROUND

A bulk carrier, or bulk material carrier, refers to a variety of devices that permit transport and/or storage of bulk material. Therefore, and by way of example, the term bulk carrier encompasses both stationary and vehicular vessels including tank-type vehicles, such as trucks or truck trailers, railway cars, such as hopper and tank-type cars, barges and the like, and may be used for bulk ladings such as liquids, food grains, and pelletized materials, to name a few. The bulk carrier often is designed to have a closable compartment in which the bulk material is received and stored, the compartment often times being sealed and possibly pressurized.

The bulk carrier typically is designed with a manhole system permitting access to the closable compartment. It should be noted that a variety of structures may be provided for the bulk material to be introduced into and/or removed from the compartment other than a manhole system. However, the manhole system allows a person to physically enter the closable compartment, such as may be required for inspecting or cleaning the compartment interior. The manhole system, nonetheless, allows bulk material to be filled into or drawn out of the compartment.

The common industry practice is for a bulk carrier to be positioned to allow an input or output apparatus to align with the manhole system. The manhole system is opened, most often by a person climbing onto the bulk carrier and manually opening the manhole cover itself by moving it from a closed position over the opening to an open position substantially away from the opening, whereupon the input or output apparatus is positioned proximate to or within the opening for introducing bulk material to, or removing bulk material from, the compartment.

For a number of reasons, it has become desirable to have the opening and closing of the manhole cover be done by remote actuation. This obviates the need for a person to climb onto the bulk carrier, and makes the opening/closing a faster operation. However, these powered systems have brought to light a new set of issues. One such issue is that, without being able to see the manhole system located on a top surface of the bulk carrier, an operator may have difficulty recognizing the exact position of the manhole cover over the opening and cannot inspect the system prior to closing to make sure it is clear of errant bulk material or other debris.

Another issue for these powered systems is the size of the manhole or cover itself. In some manhole designs, the manhole cover shifts in a straight line along a longitudinal direction of the bulk carrier away from the opening. Such a system may utilize a piston for shifting the manhole cover in one direction, which necessitates the piston being at least greater than the size of the manhole cover itself, as well as a rail system for supporting the manhole cover as it moves away from the opening. This leads to a large and possibly expensive system, and the rails may have to be precisely positioned along the top of the bulk carrier which itself may be a rounded tank surface. This makes it difficult to retrofit or install the manhole system on a bulk carrier.

Another manhole system has the cover pivot upwardly. As the manhole cover is relatively large and made of metal, its weight requires a large piston in order to accommodate the large torque required to lift the manhole cover. Furthermore, the manhole cover in an upright position is an obstruction to equipment used for loading and unloading the bulk material from the carrier.

A manhole system shown in U.S. Pat. No. 6,053,348, to Morch, shows a manhole cover that is pivoted around a substantially vertical axis. This system utilizes an actuating mechanism positioned between the axis and opening so that a relatively short piston may be used to shift the manhole cover between open and closed positions. However, the manhole system of the '348 patent still suffers from a number of deficiencies. For instance, an operator of the manhole system of the '348 patent is still unable to determine the exact position of the manhole cover.

Of greater concern is the locking of the manhole cover. It is common for manhole systems to have braces or catches to assist in locking the manhole cover in the closed position. One or more catches are mounted with a stationary portion of the system or with the bulk carrier itself, such as an upstanding annular lip formed on the bulk carrier, and one or more catches are also provided on the manhole cover. When the manhole cover is moved to the closed position, the stationary catches engage with the manhole cover, and the manhole cover catches engage with the stationary portion of the system or the bulk carrier.

In non-powered manhole systems, the operator would manually shift the catches between locked and unlocked positions. With the powered systems, the catches have but a single position. As the catches need to permit the manhole cover to shift between the open and closed positions, their effectiveness in securing with the manhole cover is less than desirable. The use of an inflatable seal between the manhole cover and the opening frame closes any space therebetween, but does not help in locking the hatch because support structures provided for permitting movement by the manhole cover, such as the rails or a pivot pin forming the pivot axis, do not allow any other type of movement of the manhole cover relative to the catches. To the extent such other type of movement occurs, it may have deleterious effects on the support structures, such as bending of the pivot pin.

Accordingly, there has been a need for an improved remotely-actuated manhole system.

SUMMARY

In accordance with an aspect of the present invention, a manhole system is disclosed having a cover that is positionable in a closed position over an opening in a compartment of a bulk carrier and is positionable in an open position away from the opening, and having a seal member that shifts the cover in the closed position from an unlocked position to a locked position. In this manner, the cover is shiftable to engage catches for securing the cover in the locked position. Preferably, both the cover and a stationary portion includes catches. The stationary portion may be a portion of the bulk carrier, may be a collar secured around the opening and with the bulk carrier, or may be a frame secured to the collar. The catches also serve to prevent movement of the cover beyond the closed position.

Preferably, the seal member has an inflated configuration providing both a seal and the locking movement of the cover. The seal member may be carried on a bottom side of the cover, or, less preferably, may be carried on the manhole system frame. The weight of the cover may be utilized to assist in deflating the seal member and acts to gravitationally shift the cover downwardly from the locked position to the unlocked position.

Preferably, the manhole system includes a pivot pin around which the cover rotates. The pivot pin provides a substantially vertical axis and is sized to permit the cover to shift vertically between the locked and unlocked positions.

The manhole system is remotely actuated and controlled by an operator. Accordingly, the cover is pivoted to and between the open and closed positions by a remotely actuated mechanism, preferably a powered mechanism such as a piston utilizing fluid or air pressure. The piston may be retractable to move the cover to the closed position and extendable to move the cover to the open position. In a preferred form, the piston includes a first portion secured with the cover and a second portion secured with the frame, each of the first and second piston portions being rotatable to permit the piston to shift relative to the cover and frame as the cover shifts between the open and closed positions. Additionally, the seal member is operable by the remotely actuated system. Furthermore, the remotely actuated system may include sensors for determining the position of the cover relative to the frame, and sensors for providing information as to operating conditions of the manhole system.

DETAILED DESCRIPTION

Referring initially toFIGS. 1-3, a manhole system10is shown secured with a bulk carrier12. The manhole system10includes a manhole cover14that is selectively shiftable or movable around a pivot axis such that the manhole cover14pivots from a closed position, as shown inFIGS. 1 and 2, to an open position, shown inFIG. 3. The bulk carrier12includes an opening16on its top surface or portion thereof, the opening16permitting ingress and egress of a person to the interior of the bulk carrier12as well as loading and unloading capabilities through the opening16for bulk material (not shown). The opening16has a central axis substantially parallel to the pivot axis and is surrounded and defined by a collar20(see alsoFIGS. 4A and 4B). Preferably, the collar20is vertically oriented and circular or annular, and it is preferably welded or otherwise integral with the bulk carrier12.

The manhole system10includes a frame22for securing with the collar20. The collar20may be part of the manhole system10, or the collar20may be part of the bulk carrier12itself. In the latter instance, utilization of such an existing collar20allows the manhole system10to be retrofitted on a bulk carrier12that previously utilized a different system for closing the opening16.

The frame22includes a circular cut-out24for receiving an upper portion of the collar20, as can be seen inFIG. 3. The frame22may be secured with the collar20in a variety of conventional manners as is readily recognized, such as welding the frame22and collar20together. Preferably, the collar20and frame22are secured together with a number of securements26, as best seen inFIGS. 4A and 4B.

In the present form, each securement26includes a brace28secured with an exterior surface30of the collar20. A pivot nut32is positioned within each brace28and secured therein by a pin34. The frame22is positioned relative to the collar20so that bolt holes36provided in a series on the frame22are aligned with the pivot nuts32. A bolt38is then inserted through each bolt hole36and threadably secured with each pivot nut32and brace28. The arrangement provided by the securements26allows the manhole system10(other than the collar20) to be easily removed or replaced, such as when the manhole system10becomes damaged, and allows for accurate placement and alignment of the manhole system10relative to the bulk carrier10. With the frame22secured to the collar20, the braces28provide support for the manhole system10itself.

The frame22has a circular portion22awith the described bolt holes26and cut-out24, and has a lower flange40extending to one side thereof. The lower flange40has a pivot opening42vertically aligned for receiving a pivot pin44around which the cover14rotates or pivots between the open and closed positions. The pivot pin44includes a lower portion48received within the pivot opening42, an upper portion50received within a recess (not shown) in the cover14, and a radial flange52extending about the pivot pin44. A washer54is positioned around the lower pin portion48, between the lower flange40and the radial flange52, to support the pivot pin44and to provide bearing surfaces between the flanges40and52. As will be described, the pivot pin44allows the cover14to rotate therearound as well as permits the cover14to shift vertically a short distance.

The cover14includes a circular portion60for covering the opening16of the collar20in the closed position and an upper flange62extending to one side thereof. The upper flange62receives the pivot pin44, as described above. For structural strength, the upper flange62includes a pivot bearing66that extends upwardly and includes the recess for receiving the pivot pin44. This allows a greater portion of the pivot pin44to be received therein and permits the above-mentioned vertical shifting of the cover14relative to the frame22. For additional support, a top side68of the cover14includes braces170extending from the pivot bearing66and upper flange62over the circular portion60.

When in the closed position, the cover14and frame22are sealed with an inflatable seal70. As can be seen inFIGS. 4A and 4B, the inflatable seal70is carried on a bottom side72of the cover14. The inflatable seal70has a first or deflated or contracted configuration and a second or inflated or expanded configuration. Once the cover14is in the closed position, the inflatable seal70is filled to the inflated configuration to cause pressure between the inflatable seal70and the collar exterior surface30, as well as pressure between the inflatable seal70and the bottom side72of the cover14. The weight of the cover14is typically sufficient to provide an excellent seal therebetween. It should be noted that the inflatable seal70may engage with the collar exterior surface30, the frame22, or both.

Inflation of the inflatable seal70also provides for engagement of catches80provided on the frame22and the cover14to restrict or prevent pivoting of the cover14after the inflatable seal70has been inflated and the tank sealed. In prior art systems, inflation of a bladder of the type shown as the inflatable seal70places a bending moment or torque on a pivot pin or axis. Over time, this can weaken or worsen the operation of the pivot pin. In any event, the prior art cover and bladder systems did not provide for a vertical shift by a cover to engage catches or hooks. Therefore, the prior art catches or hooks provided only a modicum of resistance to shifting of a cover. In the present manhole system10, the pivot pin44is sized to permit the cover14to shift upwardly, relative to the frame and the pivot pin44, due to the inflation of the inflatable seal70. This allows for more positive engagement by the catches80. The catches80also serve to assist in defining the closed position for the cover14as they prevent over-rotation or rotation beyond the closed position by the cover14relative to the frame22.

More specifically and in the present form, the frame22includes three frame catches80athat are stationary while the cover14carries three cover catches80bwhich move along with the cover14. Each catch80, as shown, has two threaded foot portions82received within holes on either the cover14or the frame22. A pair of nuts84are used to precisely position and retain the catch80with the cover14or the frame22. The catch80is shaped to define a receiving space86between it and its supporting structure, either the cover14or the frame22. As can be seen, the frame catches80aextend upwardly from the frame circular portion22awhile the cover catches80bextend downwardly from the cover circular portion60, each to define the receiving space86. The catches80are positioned on their supporting structures so that, when the cover14is in the closed position, the frame catches80areceive a portion of the cover14in their receiving spaces86awhile the cover catches80breceive a portion of the frame22in their receiving spaces86b.

With the cover14in the closed position and the frame22and cover14received in the respective receiving spaces of the catches80, the inflatable seal70is then inflated. This first creates the seal between the frame22and cover14and also lifts the cover14upwardly so that the frame catches80aengage with the cover14and so that the cover catches80bengage with the frame22.

The operation of the manhole system10is remotely actuated and controlled. To shift the cover14between the open and closed positions, a piston100is provided which is, for instance, driven by fluid such as by being pneumatically or hydraulically actuated. The piston100has a frame end102secured with the frame lower flange40, on a bottom side thereof. The frame end102is secured via a bolt104that permits the piston100to rotate about its frame end as the cover14moves. The piston100also has a cover end106secured with the cover upper flange62, also via a bolt108that permits rotation of the piston thereabout during movement of the cover14. During operation, the piston100is extended to force the cover14to rotate around the pivot pin44to the open position, or the piston100is retracted to rotate the cover14to the closed position.

The manhole system10includes one or more pressure lines110for shifting the cover14and for inflating the inflatable seal70. As can be seen inFIG. 4B, the pressure lines110are mounted on the frame lower flange40to be in fluid communication with the piston100. One of the pressure lines10acommunicates with a connector112, which is itself joined by a line113(FIG. 2) to the inflatable seal70. It should be noted that alternative arrangements for the pressure lines110may be utilized. Sensors are provided as part of the operating piston100so that the operator may be advised as the to exact position of the cover14as well as to certain operating conditions, such as an effective seal and proper engagement by the catches80. Some of these control features are described in U.S. Pat. No. 6,952,996, to Sisk, et al., which is incorporated in its entirety herein by reference. As a result, normal operation of the manhole system10obviates the need for an operator to climb aboard the bulk carrier12, instead remaining on the ground and in more safe position.