MANHOLE LOCK SYSTEM

A manhole lock system includes a frame positioned over an access opening, a cover movable between a closed position in which the cover extends over the access opening, and an open position in which the access opening is exposed; and a lock mechanism for locking the cover in the closed position. The lock mechanism includes a lock member that is movable along a path between a unlocked position and a locked position, wherein in the locked position the lock member prevents the cover from moving to the open position, wherein in the unlocked position the lock member is retracted to enable movement of the cover to the open position.

BACKGROUND OF THE INVENTION

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.

SUMMARY OF THE INVENTION

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.

DESCRIPTION OF THE CURRENT EMBODIMENT

A manhole lock system, in accordance with an embodiment of the invention is illustrated in the drawings and generally designated10.

In the embodiment illustrated in the Figures, the system10includes a cover12, which has a lower surface13, an upper surface14, an outer peripheral edge16. A lock mechanism18is positioned on cover12, and includes a lock member20that is movable between a locked position in which the cover12is prevented from opening and an unlocked position in which the cover can be opened by a user.

In the illustrated embodiment, the cover12is 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 cover12can 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 cover12is 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 cover12includes an upper surface14that can include insignia, designs, demarcations, and/or depressions or channels for funneling excess water off of the cover12. In one embodiment, the upper surface14may include projections and designs that indicate the owner of the cover10, the manufacturer, the type of infrastructure beneath the manhole or any other pattern. In one embodiment, the cover12is generally circular, and includes a generally circular outer peripheral edge16. In the illustrated embodiment, the cover12includes a pair of hinge portions22extending from the outer peripheral edge16for hingedly connecting to a frame24as described in more detail below. Although shown as a circular, hinged cover, the cover12may alternatively have a variety of shapes, and may be unconnected from the frame24for free removal from the frame24.

In the embodiment shown inFIGS.1-12, the cover12defines a lock opening32for receiving a lock housing50. Referring toFIGS.1and2, for example, the lock opening32may extend through the cover12such that the lock housing50can be inserted into the lock opening32with an upper wall82of the housing50generally flush with the upper surface14of the cover12and the lock member20extending through the lock opening and below the lower surface13of the cover12. In another embodiment, the cover12may include one or more additional openings for assisting in lifting the cover12. For example, as shown inFIG.1, the cover12includes a first lift opening36and a second lift opening38. These lift openings36,38may be in fluid communication with each other, and may be designed to receive a pry bar, pick, or other device for assisting a user in lifting the cover12to an open position. An alternative embodiment is shown inFIGS.13and14, wherein the lock housing50′ is cast into the cover12′ during the formation of the cover12′, such that the lock housing50′ is unitary with the cover12′ instead of being inserted into a lock opening32. All other features of the cover12′ are the same as the cover12ofFIGS.1-12and thus not discussed again in detail.

In one embodiment, the frame24is shaped to receive the cover12. In the illustrated embodiment, the frame24is 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 frame24can 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 frame24is 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 frame24defines an access opening40that may sit atop and define the entrance to a manhole, an underground utility system, a vault, a utility room, or the like. The frame24generally includes a sidewall42having a base44and an upper rim46. The base44forms a ground engaging portion of the frame24, and may include an outwardly extending mounting flange48defining one or more mounting holes51for receiving fasteners (not shown) for bolting or otherwise attaching the frame24to a ground surface or another surface. In the illustrated embodiment, the sidewall42is generally circular, and sized to match the shape of the outer peripheral edge16of the cover12, such that the cover12can fit closely within the frame24to cover the access opening40. As shown, the sidewall42includes an inner surface52. And in the embodiment shown inFIGS.1-12, the inner surface includes an inwardly extending frame seat54that is spaced downwardly from the upper rim46and forms a seat for the lower surface13of the cover12. In one embodiment, the seat54is positioned on the sidewall42such that the upper surface14of the cover12is flush with the upper rim46when the cover12is seated on the seat54. In an alternative embodiment, shown inFIG.15, the frame14′ may have a sidewall42′ that does not include an inwardly extending cover seat. For example, as shown inFIG.15, the sidewall42′ includes an outwardly extending flange53′ that forms a seat for the cover12. In such an embodiment, the lock member20(as described in more detail below) may engage directly with the inner surface52′ of the sidewall42′ rather than an inwardly extending portion.

Also in the embodiment ofFIGS.1-12, the frame24defines a pair of hinge housings56defined by outwardly extending U-shaped sections of the sidewall42. Each hinge housing56includes structure for interfitting with an associated one of the hinge portions22of the cover12. The hinge housings56and hinge portions22may hingedly connected in a variety of ways. In one embodiment, the hinge housings56each include a post (not shown) and the hinge portions22a hook (not shown) that fits over the associated post to enable the cover12to pivot between the closed position in which the cover12is seated on the frame24and covering the access opening40, and an open position (such as that shown inFIG.2), wherein the cover12is at least partially removed from the frame24to provide access to the access opening40. An alternative, non-hinged embodiment is shown inFIG.16. In this embodiment, the cover12″ includes a hook55″ opposite the lock mechanism18. The hook55″ functions to retain the cover12″ on the frame14by hooking under the frame seat54when the cover12′ is positioned on the frame14.

The lock mechanism18is positioned on the cover12to provide a structure to hold the cover12in the closed position (as shown, for example, inFIG.1). As noted above, the lock mechanism18may be formed with the cover12, such as being cast with the cover12during the casting process, or it may be inserted into a lock opening as shown inFIGS.1-12, and may alternatively be provided as a standalone lock mechanism unit for covers of a variety of materials, whether formed with the cover or attached to retrofit an existing cover. The lock mechanism18requires no modification of the frame14, such that the lock mechanism18can be fitted, or retrofitted, onto a variety of covers for a variety of different frames and frame styles.

In one embodiment, the lock mechanism18includes the lock member20and the lock housing50. The lock member20is a movable member that includes an interference surface60, a retention surface62, a catch64, and structure for slidably mounting the lock member20to the lock housing50. In one embodiment, the interference surface60forms a leading edge of the lock member20, positioned nearest to the outer peripheral edge16of the cover12. As shown, the interference surface60includes a toothed portion66nearest to the outer peripheral edge16and a flat portion68extending from the toothed portion66to the retention surface62. The toothed portion66is optional, and may not be included, for example, in an embodiment where it is known that the lock mechanism18will be positioned on a cover12that will be attached to a frame14with a cover seat54. The retention surface62is a flat surface that extends at an angle from the interference surface60, and in the illustrated embodiment, the retention surface is generally parallel to the cover12whereas the interference surface60extends at about a 45 degree angle from the retention surface62. As described in more detail below, the catch64is positioned and shaped to be engaged by a removal tool34that can pull the lock member20to move the lock member20and enable movement of the cover12. As shown, the catch64is positioned at a rear edge of the lock member20and is generally hook shaped, although other positions and shapes may be used.

As noted, the lock member20includes structure for slidably mounting the lock member20to the lock housing50. In one embodiment, this structure includes a lock member slot70and a post hole72. The lock member slot70is a generally open slot defined in the lock member20and capable of receiving a housing post74affixed to the housing50as described in more detail below. The post hole72is a hole or opening formed in the lock member20for receiving a post94such that the post94extends from and moves with the lock member20. In one embodiment, the post hole72is sized to receive a post94in the form of a bolt or other fastener. In another embodiment, as an alternative to a post hole72, a post94may simply be affixed to and extend laterally from the lock member20.

In the illustrated embodiment, shown, for example, inFIG.9, the lock housing50includes an upper wall82and a pair of spaced apart housing sidewalls84,86extending from the upper wall82. The lock member20is slidably mounted within the housing, between the sidewalls84,86. As illustrated, each of the housing sidewalls84,86defines a slot88that determines the path of sliding travel for the lock mechanism18. More particularly the slots88each have a first end90(seeFIG.11), a second end92, and a longitudinal extent therebetween. The slots88are sized to receive the post94extending from and moveable with the lock member20, wherein the post94can travel along the slots88by sliding along the slots88between a first, or locked, position at the first end90and a second, unlocked position at the second end92. In the illustrated embodiment, this path is angled with respect to the upper wall82of the housing50and with respect to the cover12or frame24. As shown, the path is angled such that the lock member20moves outwardly (i.e., away from the center of the cover12and toward the peripheral edge) and downwardly (i.e., away from the lower surface13of the cover12). In this way, the lock member20is caused to slide down the slots88to the first end90as a result of gravity when the cover12is near the closed position. In one embodiment, the slots88are angled at about 45 degrees from the upper wall82of the housing and from the lower surface13of the cover12. In other embodiments or applications (such as an application where the cover12is not installed on a flat, horizontal surface), the angle of the slots88may be another angle that enable the lock member20to slide down the slots88and remain in the second position of the slots88when the cover12is closed, without the need for a spring or another force to hold the lock member20in the second position. Notably, although the illustrated embodiment shows the slots88positioned on the housing50, a slot that controls the path of the lock member20could alternatively be positioned on the lock housing50. The slots88also provide a “slam latch” function, wherein the cover12can be closed without manipulation of the lock member20by the user because in the case of interference between the lock member20and the frame14as the cover is closed, the lock member20will simply slide up the slots88until there is no further interference and the cover12can close. The angle and position of the slots88can also make the lock member20adaptable to a wide variety of frames, leaving a gap between the lock member20and the frame14when the lock member20is in the locked position, such that the lock member20can fit with frames of different shapes and sizes without readjustment of the lock member20.

The lock housing50may additionally include structure for enabling the manual release of the lock member20, and for securing the lock member20in the locked position. In one embodiment, the upper wall82of the lock housing defines a release opening96extending through the upper wall82. The release opening96extends through the upper wall82, and as illustrated the release opening96has a keyhole shape wherein the release opening96has a first, generally wider section98, and a second, generally narrower section100. The narrower section100may be positioned closer to the outer peripheral edge16. Referring toFIGS.4,6and7, the release opening96is positioned with respect to the lock member20and the lock housing50such that the catch64is accessible through the release opening96by a removal tool34. The release opening96and removal tool34may be constructed to correspond to one another, such that the removal tool34is shaped and sized to be inserted through the release opening96, into the lock housing50, and into engagement with the catch64in such a manner that a user can pull on the removal tool34to draw the lock member20from the locked position to the unlocked position. In the illustrated embodiment of the removal tool34, it includes a generally straight stem110, having a handle112at one end and a hook114at the opposite end. The release opening is sized such that the user can insert the hook114through the wider section98of the release opening96and underneath the catch64with the handle112extending from the upper surface14of the cover12. Referring toFIG.11, in one embodiment, the removal tool34includes a shoulder103on the stem110, which enables a user to move the stem110into the narrower section100of the opening102when the lock member20is released such that the shoulder103holds the removal tool34in the release position.

In another embodiment, the upper wall82includes a secondary lock opening102defined in the upper wall82generally adjacent to the release opening96. As illustrated, for example, inFIG.4, the secondary lock opening102is positioned between the release opening96and the outer peripheral edge16. The secondary lock opening102is aligned above the lock housing50, and above the retention surface62of the lock member20to enable insertion of a device through the secondary lock opening102that can engage the retention surface and prevent movement of the lock member20. The secondary lock opening102may be a fastener receptacle, such as a threaded receptacle for receiving a retaining a threaded lock fastener104. The threaded lock fastener104can be threaded into the secondary lock opening102to engage, or sit adjacent to, the retention surface62to hold the lock member20in place in the lock position at the second end92of the slot88. The secondary lock opening102and lock fastener104provide a secondary or backup means as an additional level of security for locking the cover12closed.

Notably, in the illustrated embodiment, the lock housing50is positioned in a lock opening32in the cover12, which enables the lock mechanism18to but in another embodiment, the upper wall82of the lock housing50could be formed unitarily with the cover12, such that the sidewalls84,86of the lock housing50extend from the lower surface13of the cover12, and the release opening96and lock opening102are defined directly in the cover12, rather than in the lock housing50.

Referring toFIGS.5,6and7, the lock mechanism18is positioned and arranged on the cover12such that the lock member20extends under a portion of the frame24(or another component) when the lock member20is in the locked position, such that the interference surface60of the lock member20engages the frame24upon an attempted opening of the cover12and prevents the cover12from being moved to an open position.FIG.5shows an example of the lock mechanism18in the locked position. In this position, the lock member20is located in the locked position, with the post94positioned at the first end90of the slot88. As noted, the pin94and lock member20will slide into this position automatically upon movement of the cover12to the closed position because the angle of the slot88includes a downward direction and the lock member20is caused to fall to the locked position. With the lock member20in the locked position, the interference surface60of the lock member extends underneath the seat portion54of the frame24. Any attempted opening of the cover12will cause the lock member20to engage the frame24and prevent movement of the cover12to an open position. In one embodiment, shown inFIG.8, there may be some play within the system that enables a slight movement of the cover12, but ultimately the cover12is still prevented from being moved to the open position. In the alternative embodiment shown inFIG.15, one or more of the lock members20may retain the cover12in a closed position as a result of the frictional interference between the lock member20and the inner surface52′ of the frame sidewall42′.

The lock member20may be additionally secured in the lock position by the lock fastener104which, when inserted and threaded through the lock opening102, engages the retention surface60of the lock member20to prevent movement of the lock member20even in the event that a removal tool34or another object is inserted into the release opening96.

FIG.6shows the cover12in a closed position but the lock mechanism18in an unlocked position. In this state, a removal tool34has been inserted into the release opening96, with the hook114engaged with the catch64of the lock member20, and with the lock member20pulled along the slot88in an inward and upward direction, such that the post94is moved to the second end92. In this position of the lock member20, the interference surface62has been retracted such that it can clear the frame24without interference as a forced is placed on the cover12, enabling the cover12to be pivoted to the open position.FIG.7shows the cover12having been lifted into an open position with the lock member20in the unlocked position. Such a position may be achieved by a user exerting a force on the handle112to pull the cover12to the open position, or via a different lift tool or method.

The metal parts described herein, including the cover12and the lock mechanism18, 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 mechanism18may be constructed with the cover12, or it may be provided as a retrofit system. In either case, the lock mechanism18is positioned on the cover12such that it is sufficiently close to the outer peripheral edge16to enable the lock member20to engage the frame24(or another fixed object) when the cover12is closed and prevent opening of the cover12without a release of the lock member20. In the closed and locked position, shown inFIG.5, the interference surface62of the lock member20is positioned underneath the seat54of the frame24, such that the lock member20engages the frame24to prevent opening of the cover12. The cover12may be additionally secured in the closed position by the threaded insertion of the threaded lock fastener104into the secondary lock opening102.

When it is desired to release and open the cover12, a user may engage the lock fastener104with a properly shaped and sized wrench or tool to remove the lock fastener104. Removal (or sufficient loosening) of the lock fastener104, as shown inFIG.6, provides a gap between the lock fastener104and the retention surface60that enables movement of the lock member20. After removal of the lock fastener104, a user may utilize the removal tool34to move the lock member20to the unlocked position. This may be completed by inserting the removal tool34into the release opening96to engage the catch64on the lock member20, and then pulling the removal tool34to slide the lock member20along the slot88to the unlocked position. More particularly, as the lock member20is pulled, the post94is moved from the first end90to the second end92of the slots88, with the slots88controlling the path of travel. At the same time, the housing post74may travel within the generally open slot72in the lock member20to maintain the angular position of the lock member20as it travels. With the post94at the second end92of the slot88, the lock member20is in the unlocked position and, as sown inFIG.6andFIG.7, the cover12can be moved to an open position without interference between the lock member20and the frame24. With the cover12in the open position, the user may access the exposed access opening40and enter the space below the frame24.

Finally, closing and locking of the cover12may be completed by lowering (or sliding, in the case of theFIG.16embodiment) the cover12from the open position to the closed position wherein the cover12is seated on the frame seat54to cover the access opening40. As the cover moves to the closed position, the lock member20may be manually retained in the unlocked position to prevent interference between the lock member20and the frame24, or alternatively the lock member20may have a “slam latch” feature as noted above, to automatically be pushed by the frame20to the unlocked position as the cover12is closed. In any case, with the cover12in, or nearly in, a closed position, the angle of the slot88in an at least partially downward direction enables the lock member20to automatically fall from the unlocked position to the locked position, and the cover12is once again prevented from opening without use of the removal tool34. The cover12may be further locked in place by reinserting or retightening the lock fastener104as a secondary form of security.