Patent Application
20090145905
This invention is an improved slide hatch for bulk carriers and in particular comprises a sliding hatch cover unit with internal seal for pressurizable tanks of the type used for cement tankers. The sliding hatch cover unit includes an actuator system that has an external actuator that displaces both an outside hatch cover and an inside sealing gate. In particular, this invention relates to a hatch cover kit that can be incorporated into a bulk carrier container at the time of manufacture or adapted as a replacement cover system for an after market carrier having a top loading port.
The slide unit hatch can be used on any bulk carrier vehicle of the type used for transport of dry powdered or granular material that is free flowing in a hopper style container. This description utilizes a cement carrier as a preferred example of the transport carrier contemplated. Bulk transport of dry cement is accomplished utilizing a gondola-style trailer that is loaded with cement from a top port by means of a hose or chute. Typically, the gondola has a tank with sloping sides that converge to a bottom discharge for gravity feed of the cement to a discharge hose that is used to pneumatically deliver the bulk cement to a destination for storage or mixing. To assist in the discharge of the fine powder cement, the gondola tank is pressurized to both compensate for volumetric displacement by the discharging cement and to assist in moving the cement to the discharge pump.
To maintain a pressure within the gondola tank, the hatch cover must have a sealed engagement with the hatch port at the top of the tank. Typically, the hatch cover is connected to the tank with a hinge and a series of threaded dogs mounted around the hatch cover. When the tank is refilled, the hatch cover must be opened which has customarily required that the driver or assistant climb to the top of the trailer and manually disengage the tie-down dogs to open the hatch. Not only is this task time consuming, but because of the configuration of the tank and carrier trailer the task is dangerous as well.
The sliding hatch cover unit of this invention relates to my U.S. Pat. No. 6,196,590, entitled “Slide Hatch for Bulk Carrier”, issued Mar. 6, 2001. In the referenced patent, a hatch cover is designed to slide over a hatch port on a track that by cam action forces the cover onto a seat around the port.
A considerable force is applied to the hatch cover when the tank is even moderately pressurized to 15 p.s.i. for fluidizing and pneumatically conveying the tank contents from the tankers.
When the bulk material is a dry powder such as cement, that tends to build-up on the cover seat, the seal begins to fail after a number of transport operations. A leaking access hatch lowers the internal tank pressure and delays the unloading process.
Internal sealing has the advantage of utilizing the force developed by the tank pressure to improve the seating and seal. However, locating an actuator assembly within a tank loading and unloading material like cement is preferably to be avoided to prevent frequent servicing in a difficult environment.
The subject invention avoids this disadvantage by mounting the primary actuator assembly external to the tank. The use of an internal sealing gate and an outside protective cover improves the longevity of the system before maintenance and cleaning is required.
In the preferred embodiment described, the cover and gate are linked with the external actuator to reciprocally slide the outer cover and raise and lower the inner gate.
It is to be understood that the sliding hatch cover unit of this invention can be utilized with a cam assisted covering system as described in the referenced patent with the primary function of the hatch cover being to cover and protect with sealing accomplished by the internal gate.
In the preferred embodiments of this invention the gate is linked to the cover by cables and operated in conjunction with the sliding of the cover as further described in the summary and detailed description of this invention.
The sliding hatch cover unit of this invention is designed for a pressurizable tanker, which carries a dry granular material that is pneumatically discharged. The sliding hatch cover unit has a track mounted hatch cover that can be displaced from a position of safety. In the embodiment disclosed, the hatch cover unit includes a hatch port gate that is internally mounted within the tank of the tanker in order to use the internal pressure of the tank when pressurized to seal the tank.
In the embodiments of the sliding hatch cover unit described, the actuator mechanism that slides the hatch cover to an open position and a closed position also actuates the internal hatch port gate. In the preferred embodiment, a piston and rod actuator mechanism is connected to the hatch cover to open and close the hatch cover. The actuator mechanism preferably utilizes a pair of compact hydraulic actuators arranged on each side of the sliding hatch cover. It is to be understood that a single rod and piston actuator that may be air driven may be utilized instead of the preferred dual actuator system. Alternately, a mechanical winch and spring return system may be employed.
In order to overcome the problem of pressure leakage around the closed hatch cover during the process of pressurizing the tank for discharge of the contents, the sealing is accomplished from the inside the tank. In this manner, the force of the internal air pressure against the closure member aids in sealing the tank. The closure member comprises a hinged flap plate that engages a gate seat on the inside of the tank port to seal the tank chamber.
The flap plate is hinged at one side to an internal mount on a cylindrical sleeve that is a component of the hatch cover kit. The plate is actuated by a cable that connects the plate to the sliding hatch cover in a manner that closes the flap plate against the gate seat when the cover is closed. When the cover is opened, the plate drops open by force of gravity.
Whether the sliding hatch cover is actuated by action of a manually operated cable system or by action of a rod in a pneumatic cylinder actuator, the displacement of the hatch cover is translated to the displacement of the hinged plate for sealing the hatch port.
In order to adapt the hatch cover kit to an existing bulk carrier tank, the adaptation must be easily accomplished with minimal modification to the existing cover system. Of primary concern is the ability to install a rugged system that will withstand the abuse of the loading mechanism and wear from often abrasive material.
Additionally, key components, such as the flap plate, must be installed through the loading port of the carrier tank. Repair and replacement of the components must be easily accomplished and, preferably, the cover system should be removable and usable as a unit on another bulk carrier tank.
These and other features will become apparent on considering the preferred embodiment described in the detailed specification that follows.
Referring to
The tank 22 typically has one or more hatches 24 with hatch covers 26 and 28 covering an opening or port 30 for filling the tanker with dry granular powdered material such as bulk cement.
A conventional hatch cover 26 has a series of perimeter bolts 32 which secure the cover 26 to an elevated rim 34, which allows the tank to be pressurized for discharge of the contents of the tank 22. Typically a discharge hose or pipe (not shown) is connected to a discharge unit 36 at the bottom of the tank 22. The released pressurized air fluidizes the contents during the discharge and pneumatically conveys the fluidized powder material to a delivery terminal.
Climbing to the top of the tank 22 on the ladder 38 at one end of the tanker 14 to undo the bolts 32 is a danger and inconvenience to an operator. To remedy this situation at least one hatch cover 28 can be removed from a position of safety. Referring to
In addition, the sliding hatch cover unit 10 includes an internal gate 48 that is preferably actuated by the actuator assembly 42 to seal the tank 22 when the hatch cover 28 is positioned over the port 30. Preferably, the hatch cover unit 10 is in the form of a compact kit that can easily be installed on an existing bulk carrier with minimal modification.
In the embodiment of
In the preferred embodiment, the gate seat 54 is located at the end of a cylindrical guide sleeve 56 installed within the tank 22. In the preferred embodiment shown, the sliding hatch cover unit 10 is incorporated onto an existing tanker 14 with minimal modification, using the installation method disclosed. A typical tanker 14 has one or more hatches 24 with elevated rims 34, having a flange 60 around the circular port 30 for attachment of a cover.
In the preferred embodiment, the sliding hatch cover unit 10 is connected to the port flange 60 and is supported in part on the top surface of the typical tank 22 of a bulk carrier 12 as an integrated assembly kit. The compact actuator assembly 42 includes a conventional hydraulic system 62, indicated schematically, that includes the hydraulic and electronic controls (not shown) for remote actuation by a driver in the cab of the carrier and/or at the side of the tanker 14.
To install the hatch cover unit 10, a notch 64 is cut into the lower portion of the original cylindrical port wall 66 that downwardly projects into the interior of the tank 22 to guide the hose or chute during the filling operation. This notch 64 allows a clevis bracket 68 to connect to the lower edge of the guide sleeve 56 without having to extend the guide sleeve 56 beyond the lower edge of the original port wall 66. The clevis bracket 68 is hingedly attached by a pin 70 to a projecting bifurcated tongue 72, extending from the underside of the circular flap plate 50. The circular flap plate 50 is sized with an outer diameter substantially equal to the inside diameter of the port 30 to enable the flap plate 50 to be inserted into the tank 22 through the port 30 before the guide sleeve 56 is inserted, which thereafter reduces the effective diameter of the port 30. The flap plate 50 has a handle bracket 74 on its upper surface that includes a hole 76 for an anchor pin 77 for anchoring a closure cable 78. The closure cable 78 and handle bracket 74 provide a convenient means to retrieve the suspended flap plate 50 for fastening after the guide sleeve 56 is inserted into the port 30 and the attached bib plate 58 is seated and bolted onto the existing flange 60 of the rim 30. In many instances, the existing dog bolt brackets 80 can be fitted with bolt sockets 82 to connect the bib plate 58 to the rim flange 60 with a series of spaced bolts 84 without substantial modification. After seating and securing the bib plate 58 and depending guide sleeve 56 to the port flange 60, the clevis bracket 68 can be attached to the guide sleeve 56. If the flap plate 50 is not already connected to the clevis bracket 68, then the plate is connected to the bracket 68 with the pin 70.
This design and method of installing the flap plate 50 and guide sleeve 56 enables the diameter of the hatch opening to be reduced only by the thickness of the guide sleeve 56 and allows the internal flap plate to be mounted as high as possible within the tank 22. In this manner, the customary loading systems can be used and the downward swing of the cover is minimized. Care must be taken in order not to overfill the tank 22, making it difficult to swing the flap plate 50 to the closed position.
The flap plate 50 has a perimeter seal 86 on the upper or top surface that contacts the gate seat 54 to seal the tank 22, particularly when the tank 22 is pressurized, forcing the flap plate 50 against the gate seat 54 of the guide sleeve 56. Between the flange 60 of the rim 34 of the tank port 30 and the underside of the bib plate 58 is a seal 88 which becomes air tight when the guide sleeve 56 and bib plate 58 are installed and secured by the perimeter bolts 84. In this manner, the sliding hatch cover 28 is not required to provide an air tight seal, but merely covers the port 30 to prevent debris or water from entering that portion of the guide sleeve 56 between the closed flap plate 50 and the upper rim 89 of the guide sleeve 56 which projects above the bib plate 58.
To displace the sliding hatch cover 28 and swing the hinged flap plate 50, the actuator assembly 42 is actuated. The actuator assembly can be a simple mechanical system with a crank and spring return, as proposed in my earlier application, or a single or double piston and rod unit. Preferably, the actuator assembly 42 is a hydraulic system with two piston and rod units 46 mounted on each side of the tank port 30 for simultaneous operation.
The bib plate 58 is generally rectangular and extends over a portion of the top of the tank 22. The bib plate 58 is supported at the far end by a shell bracket 90 that seats on the top of the tank 22 as shown in
The closure cable 78, which is attached to the anchor pin 77 of the flap plate 50 at one end, is anchored to a cable retainer 112 on the top side of the bib plate 58 at its other end. When the cover 28 is displaced, the closure cable 78 simultaneously slackens and lowers the flap plate 50, thereby opening the port for filling. The closure cable 78 is carried over a pulley assembly 114 mounted on the underside of the cover 28 and through a notch 115 in the upper rim 89 of the guide sleeve 56 and causes the flap plate 50 to lift when the rod component 104 is retracted and the cover 28 displaced to the closed position, stretching the closure cable 78 over the port opening. As apparent, the cable 78 in the open position is out of the way and does not interfere with the filling of the tank 22. The bib plate 58 has a cross seal 116 that provides a cover stop and front cover seal on closure, and a cross seal 118 mounted under the cover adjacent the cross member 108 that connects to the piston and rod units 46. In this manner, with only minor modification to the existing hatch, a sliding hatch cover 28 can be installed as a unit to an existing port 30.
While, in the foregoing, embodiments of the present invention have been set forth in considerable detail for the purposes of making a complete disclosure of the invention, it may be apparent to those of skill in the art that numerous changes may be made in such detail without departing from the spirit and principles of the invention.
