Patent Application
20240191455
The present invention relates to manhole closure assemblies and, more particularly, to a manhole lock system that can be utilized to maintain a manhole cover in a closed position.
Manholes, also known as utility holes or access openings, are both well-known and widely utilized. Manholes are generally utilized as means for providing an access opening for accessing an infrastructure, such as utilities, underground pipelines or cabling. Because manholes are essentially open holes into which an individual can fall, manhole covers, or utility covers, are utilized to prevent entry into the manhole. A traditional manhole cover rests on a frame that is attached to the substructure above the infrastructure to be maintained. The cover rests on the frame and must be lifted and moved, or in some cases pivoted on hinges, in order to gain access to the access opening and the infrastructure beneath the manhole. Typically, manhole covers are formed of iron or other heavy metals and thus can weigh in excess of 100 pounds, creating a cover that is cumbersome to lift and otherwise maneuver. Although it can make manipulation of the cover difficult, the weight of the manhole cover is a benefit in that it helps to prevent the cover from being inadvertently removed from the frame, for example, by the force of passing vehicle traffic. It also helps to deter removal of the cover by unauthorized individuals, and theft of the contents underneath the cover.
It is known to lock or latch a manhole cover to the surrounding frame. In many applications, the lock mechanism is intended to be tamperproof. The frequency with which the lock is used, i.e., locked and unlocked, may be high or low, depending on the circumstances. In many instances though a manhole cover will remain locked for a considerable period.
In an effort to effectuate a locking mechanism, various padlock configurations, keyed locks or other similar locking devices have been utilized. But the use of such locks can be cumbersome and difficult to utilize. They may also fail over long periods of exposure to environmental conditions.
The present invention provides a manhole lock system that includes a manhole cover with a lock member for a simple and robust method of maintaining the manhole cover in a closed position. The lock member is movable between locked and unlocked positions to selectively hold the cover in place in the closed position.
In one embodiment, the cover has an upper surface, a lower surface and an outer peripheral edge, and the movable lock member is positioned adjacent to the lower surface of the cover, the lock member is movable along a path between a unlocked position and a locked position, the path being angled such that the lock member travels outwardly toward the peripheral edge and also away from the lower surface as the lock member travels along the path from the unlocked position to the locked position. And in one embodiment, the lock member slides along the path from the unlocked position to the locked position under the force of gravity.
The lock member may be connected to the cover by a lock housing, with the lock member slidable within the lock housing. One of the lock member and the lock housing may define a slot, and the other of the lock member and the lock housing may include a post extending into the slot, the post sliding within the slot between the unlocked position and the locked position.
In one embodiment, one of the cover and the lock housing define a release opening. The release opening is aligned with the lock housing to provide access to the lock member through the release opening, although the function of the release opening may not be readily apparent from the exterior of the cover. The lock member may include a catch that can be accessed through the release opening to enable a user to pull the lock member along the path from the locked position to the unlocked position. In one embodiment, the release opening and the housing are shaped to correspond to the shape of a specific removal tool, wherein the removal tool is capable of being inserted through the release opening to engage the catch and pull the lock member to the unlocked position. One of the cover and the lock housing may also define a secondary lock opening, wherein the secondary lock opening may be threaded and can receive a device such as a threaded fastener or a security style fastener that engages the lock member to prevent movement of the lock member.
In one embodiment, the manhole lock system includes a frame, the cover capable of being positioned on the frame over an access opening to cover the access opening, and wherein the lock member engages the frame to prevent removal of the cover from the frame when the lock member is in the locked position, and the lock member is clear of the frame to enable movement of the cover from covering the access opening when the lock member is in the unlocked position.
These and other objects, advantages, and features of the invention will be readily understood and appreciated by reference to the detailed description of the current embodiment and the drawings.
A manhole lock system, in accordance with an embodiment of the invention is illustrated in the drawings and generally designated 10.
In the embodiment illustrated in the Figures, the system 10 includes a cover 12, which has a lower surface 13, an upper surface 14, an outer peripheral edge 16. A lock mechanism 18 is positioned on cover 12, and includes a lock member 20 that is movable between a locked position in which the cover 12 is prevented from opening and an unlocked position in which the cover can be opened by a user.
In the illustrated embodiment, the cover 12 is a ductile iron cover. Ductile iron is a cast iron that has been treated while molten with an element such as magnesium or cerium to induce the formation of free graphite as nodules or spherulites, which imparts a measurable degree of ductility to the cast metal. Ductile iron is also known as nodular cast iron, spherulitic graphite cast iron, and spheroidal graphite (SG) iron. In other embodiments the cover 12 can have other shapes and can use different materials known to those of skill in the art. Such materials include, but are not limited to, cast iron, grey iron, polymeric, composite, and fabricated steel or aluminum. In the illustrated embodiment, the cover 12 is made of a single material; however, multiple materials can be used without departing from the spirit of the present invention. Suitable alternative materials and combinations of materials are known to those of skill in the art.
The cover 12 includes an upper surface 14 that can include insignia, designs, demarcations, and/or depressions or channels for funneling excess water off of the cover 12. In one embodiment, the upper surface 14 may include projections and designs that indicate the owner of the cover 10, the manufacturer, the type of infrastructure beneath the manhole or any other pattern. In one embodiment, the cover 12 is generally circular, and includes a generally circular outer peripheral edge 16. In the illustrated embodiment, the cover 12 includes a pair of hinge portions 22 extending from the outer peripheral edge 16 for hingedly connecting to a frame 24 as described in more detail below. Although shown as a circular, hinged cover, the cover 12 may alternatively have a variety of shapes, and may be unconnected from the frame 24 for free removal from the frame 24.
In the embodiment shown in
In one embodiment, the frame 24 is shaped to receive the cover 12. In the illustrated embodiment, the frame 24 is formed of grey iron. Grey iron is an iron-carbon alloy (and a form of cast iron) with carbon contents in excess of 2%, generally in the range 2 to 4% with the addition of about 1% silicon. Grey iron is typically different from steel because the carbon present exceeds the solubility limit of 1.7%. This carbon is present in the form of austenite while the excess exists as graphite at room temperature. Consequently, grey irons are sometimes referred to as steels with graphite in them. The structure of grey irons often display three phases, ferrite, pearlite or martensite. Grey iron may be used because of its beneficial properties including, but not limited to, wear resistance, higher electrical resistance compared to steels, and that the corrosion resistance of grey irons is superior to that of carbon steel. In other embodiments, the frame 24 can have other shapes and can use different materials known to those of skill in the art. Such materials include, but are not limited to, cast iron, grey iron, polymeric and composite materials. In the illustrated embodiment, the frame 24 is made of a single material; however, multiple materials can be used without departing from the spirit of the present invention. Suitable alternative materials and combinations of materials are known to those of skill in the art.
The illustrated frame 24 defines an access opening 40 that may sit atop and define the entrance to a manhole, an underground utility system, a vault, a utility room, or the like. The frame 24 generally includes a sidewall 42 having a base 44 and an upper rim 46. The base 44 forms a ground engaging portion of the frame 24, and may include an outwardly extending mounting flange 48 defining one or more mounting holes 51 for receiving fasteners (not shown) for bolting or otherwise attaching the frame 24 to a ground surface or another surface. In the illustrated embodiment, the sidewall 42 is generally circular, and sized to match the shape of the outer peripheral edge 16 of the cover 12, such that the cover 12 can fit closely within the frame 24 to cover the access opening 40. As shown, the sidewall 42 includes an inner surface 52. And in the embodiment shown in
Also in the embodiment of
The lock mechanism 18 is positioned on the cover 12 to provide a structure to hold the cover 12 in the closed position (as shown, for example, in
In one embodiment, the lock mechanism 18 includes the lock member 20 and the lock housing 50. The lock member 20 is a movable member that includes an interference surface 60, a retention surface 62, a catch 64, and structure for slidably mounting the lock member 20 to the lock housing 50. In one embodiment, the interference surface 60 forms a leading edge of the lock member 20, positioned nearest to the outer peripheral edge 16 of the cover 12. As shown, the interference surface 60 includes a toothed portion 66 nearest to the outer peripheral edge 16 and a flat portion 68 extending from the toothed portion 66 to the retention surface 62. The toothed portion 66 is optional, and may not be included, for example, in an embodiment where it is known that the lock mechanism 18 will be positioned on a cover 12 that will be attached to a frame 14 with a cover seat 54. The retention surface 62 is a flat surface that extends at an angle from the interference surface 60, and in the illustrated embodiment, the retention surface is generally parallel to the cover 12 whereas the interference surface 60 extends at about a 45 degree angle from the retention surface 62. As described in more detail below, the catch 64 is positioned and shaped to be engaged by a removal tool 34 that can pull the lock member 20 to move the lock member 20 and enable movement of the cover 12. As shown, the catch 64 is positioned at a rear edge of the lock member 20 and is generally hook shaped, although other positions and shapes may be used.
As noted, the lock member 20 includes structure for slidably mounting the lock member 20 to the lock housing 50. In one embodiment, this structure includes a lock member slot 70 and a post hole 72. The lock member slot 70 is a generally open slot defined in the lock member 20 and capable of receiving a housing post 74 affixed to the housing 50 as described in more detail below. The post hole 72 is a hole or opening formed in the lock member 20 for receiving a post 94 such that the post 94 extends from and moves with the lock member 20. In one embodiment, the post hole 72 is sized to receive a post 94 in the form of a bolt or other fastener. In another embodiment, as an alternative to a post hole 72, a post 94 may simply be affixed to and extend laterally from the lock member 20.
In the illustrated embodiment, shown, for example, in
The lock housing 50 may additionally include structure for enabling the manual release of the lock member 20, and for securing the lock member 20 in the locked position. In one embodiment, the upper wall 82 of the lock housing defines a release opening 96 extending through the upper wall 82. The release opening 96 extends through the upper wall 82, and as illustrated the release opening 96 has a keyhole shape wherein the release opening 96 has a first, generally wider section 98, and a second, generally narrower section 100. The narrower section 100 may be positioned closer to the outer peripheral edge 16. Referring to
In another embodiment, the upper wall 82 includes a secondary lock opening 102 defined in the upper wall 82 generally adjacent to the release opening 96. As illustrated, for example, in
Notably, in the illustrated embodiment, the lock housing 50 is positioned in a lock opening 32 in the cover 12, which enables the lock mechanism 18 to but in another embodiment, the upper wall 82 of the lock housing 50 could be formed unitarily with the cover 12, such that the sidewalls 84, 86 of the lock housing 50 extend from the lower surface 13 of the cover 12, and the release opening 96 and lock opening 102 are defined directly in the cover 12, rather than in the lock housing 50.
Referring to
The lock member 20 may be additionally secured in the lock position by the lock fastener 104 which, when inserted and threaded through the lock opening 102, engages the retention surface 60 of the lock member 20 to prevent movement of the lock member 20 even in the event that a removal tool 34 or another object is inserted into the release opening 96.
The metal parts described herein, including the cover 12 and the lock mechanism 18, can be machined, sand cast investment cast or otherwise formed using suitable techniques and apparatus. Sand casting is a process in which a pattern is made in the shape of the desired part. This pattern may be made out wood, plastic or metal. Simple designs can be made in a single piece or solid pattern. More complex designs are made in multiple parts, called split patterns. A split pattern has a top or upper section, called a cope, and a bottom or lower section called a drag. Both solid and split patterns can have cores inserted to complete the final part shape. Where the cope and drag separates is called the parting line. When making a pattern it is often best to taper the edges so that the pattern can be removed without breaking the mold.
The patterns are then packed in sand with a binder, which helps to harden the sand into a semi-permanent shape. Once the sand mold is cured, the pattern is removed leaving a hollow space in the sand in the shape of the desired part. The pattern is intentionally made larger than the cast part to allow for shrinkage during cooling. Sand cores can then be inserted in the mold to create holes and improve the casting's net shape. Simple patterns are normally open on top and melted metal is poured into them. Two piece molds are clamped together and melted metal is then poured into an opening, called a gate. If necessary, vent holes can be created to allow hot gases to escape during the pour. The pouring temperature of the metal should be a few hundred degrees higher than the melting point to assure good fluidity, thereby avoiding prematurely cooling, which will cause voids and porosity. When the metal cools, the sand mold is removed and the metal part is ready for secondary operations, such as machining and plating.
Investment casting is a casting process in which an expendable pattern is surrounded by an investment compound and then baked so that the investment is hardened to form a mold and the pattern material may be melted and run off. Investment castings can be used to produce intricate and metallurgical accurate castings with very tight tolerances. This method is used to mass produce parts with near net dimensions and a high quality “as cast finish” thereby producing a visually attractive finish and reducing machining cost.
In this process an expendable pattern is made, normally by injecting wax or plastic into a metal mold. The pattern is then coated, by either pouring or dipping, with a refractory slurry (watery paste of silica and a binder) that sets at ambient temperature to produce a mold or shell. After hardening, the mold is turned upside down and the expendable pattern (wax or plastic) is melted out of the mold. To complete this refractory mold, ceramic cores may be inserted. Investment castings can be made in almost any pourable metal or alloy.
As noted, the lock mechanism 18 may be constructed with the cover 12, or it may be provided as a retrofit system. In either case, the lock mechanism 18 is positioned on the cover 12 such that it is sufficiently close to the outer peripheral edge 16 to enable the lock member 20 to engage the frame 24 (or another fixed object) when the cover 12 is closed and prevent opening of the cover 12 without a release of the lock member 20. In the closed and locked position, shown in
When it is desired to release and open the cover 12, a user may engage the lock fastener 104 with a properly shaped and sized wrench or tool to remove the lock fastener 104. Removal (or sufficient loosening) of the lock fastener 104, as shown in
Finally, closing and locking of the cover 12 may be completed by lowering (or sliding, in the case of the
The above description is that of the current embodiment of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. Any reference to claim elements in the singular, for example, using the articles “a,” “an,” “the” or “said,” is not to be construed as limiting the element to the singular.
