WO2009035349A2

WO2009035349A2 - Improvements to closures for subsurface chambers

Info

Publication number: WO2009035349A2
Application number: PCT/NZ2008/000241
Authority: WO
Inventors: David Edward Hill; Sergio Felipe Calderon
Original assignee: Sika Technology Limited
Priority date: 2007-09-13
Filing date: 2008-09-15
Publication date: 2009-03-19
Also published as: WO2009035349A3

Abstract

Invention is a latch to secure a hatch to a frame of a sub-surface chamber. The latch has a latch mounting body and a main driving member pivoted from a first pivot axis of the latch mounting body. Also present is a securing member, pivoted from a second pivot axis from the latch mounting body, and a secondary driving member pivoting between distal ends of the main driving member and the securing member via third and fourth pivoting axes respectively. The latch mounting body, main driving member, securing member and secondary driving member (collectively “members”) are arranged as a four-bar linkage. The securing member and the main driving member are crossed over each other when the latch is unlocked, and when in a locked position the latch mounting body and members form an over centre latch with the securing member located between the first and third pivot axes.

Description

IMPROVEMENTS TO CLOSURES FOR SUBSURFACE CHAMBERS

The present invention relates to hatches and frames for subsurface chambers, and in particular to retaining and locking a hatch or cover to such a frame for a subsurface chamber.

Traditionally hatches for frames for subsurface chambers and the like have been held down by there sheer weight. This was particularly the case when the hatch and frame where made from cast iron. The degree of strength required that the resulting hatch was heavy enough to deter people from lifting or removing the hatch and also prevent lifting by vehicles passing over it.

Increasingly however, the security of utilities and similar in a subsurface chamber has required or necessitated the ability to lock the hatch to the frame to provide security to the utility and subsurface chamber. This is desirable when for example the utility itself is dangerous e.g. high voltage electricity or gas, or is a sensitive utility such as telecommunications and the like.

Once such way of securing the hatch to the frame is by use of threaded connectors that thread through the hatch into receiving portions in the frame to retain the hatch to the frame.

In other methods a fastener may deploy from either the hatch or the frame to engage the frame or the hatch and may be a turn key style where a part is deployed from the hatch or frame to engage the frame or hatch.

A short coming of these methods is that to achieve sufficient security and hold down of the hatch either numerous turns of the threaded component are required, or the leverage required to produce a firm closure is sufficiently high to make it difficult to achieve with normal or even specialised tools. Further, such closures are not self tensioning and therefore over time wearing of the surfaces of the engagement of the hatch to the frame can cause loosing to the point where dynamic forces may be imparted resulting in fracturing and/or breaking of components.

In the situation where standard connectors or fasteners are used there is little security provided because standard tools can be used to open the hatch. In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art.

It is therefore an object of the present invention to provide a closure for a subsurface chamber that at least goes some way to overcoming the above problems, or at least provide to the public for the useful choice.

In a first aspect the present invention may be said to broadly consist in a latch to selectively secure a hatch to a frame of a sub-surface chamber, comprising or including, a latch mounting body, from which is pivotally mounted, a main driving member to pivot about a first pivot axis on said latch mounting body, and a securing member with a proximal end and a distal end, said securing member pivoted relative said latch mounting body via a second pivot axis at or toward said proximal end, said distal end having an engagement portion, and a secondary driving member extending between and pivotally engaged i) at or towards an end of said main driving member distal from said first pivot axis, at a third pivot axis, and ii) to said securing member via a fourth pivot axis intermediate of said distal end and said second pivot axis, wherein said latch has an unlocked position wherein said engagement portion is free of a retainment portion of, a) said frame when said latch is mounted to said hatch, or b) said hatch when said latch is mounted to said frame, and a locked position wherein said engagement portion can retain said latch to said retainment portion, said latch in said locked position has, said third pivot axis and said fourth pivot axis aligned in a line at least substantially parallel to, or inclined at an acute angle to toward said engagement portion a line between said first pivot axis and said third pivot axis, with said fourth pivot axis lying between said first pivot axis and said third pivot axis.

Preferably said latch is located in or on said hatch to engage and selectively retain said hatch to an at least in part hatch surround or frame.

Preferably said latch is moved between said locked and unlocked position by a driving tool engaging with and rotating said driving member.

Preferably said latch mounting body is U shaped in plan view, the open part of the U shape oriented towards said retainment portion.

Preferably said retainment portion is sprung loaded against the engagement of said engagement portion.

Preferably said retainment portion is a leaf spring biased against said engagement portion when in said locked position.

Alternatively said retainment portion is a sprung bar retained at either end.

Preferably said latch when moving toward said locked position loads against said retainment portion to pull said hatch into or onto said frame.

Preferably said driving tool is an elongate member with a handle distal to its driving member engaging end.

Preferably said driving tool can also engage said hatch to facilitate it being lifted from said frame.

Preferably said driving tool is not removable from said latch when said latch is in said unlocked position.

Preferably said driving tool under-engages a portion of said latch mounting body or said hatch when in said unlocked position to prevent its removal from said driving member.

Preferably the interface of contact surfaces of said retainment portion and said engagement portion lie in a plane that is substantially horizontal.

Preferably said engagement portion under-engages said retainment portion when in said locked position.

Preferably in said locked condition said latch is covered by a removable cover. - A -

Preferably each said pivot first, second, third and fourth axes are parallel to one another.

Preferably said latch can be secured to prevent its actuation.

Preferably said latch can be secured in said locked position via a locking slide that prevents; a) rotation of said main driving member by either or both by i) directly engaging said main driving member, or ii) indirectly by preventing engaging of tooling into said main driving member to rotate it.

In a further aspect the present invention may be said to broadly consist in a latch to selectively secure a hatch to a frame of a sub-surface chamber, comprising or including, a latch mounting body, a main driving member, pivoted from a first pivot axis from said latch mounting body, a securing member, pivoted from a second pivot axis from said latch mounting body and a secondary driving member pivoting between distal ends of said main driving member and said securing member via third and fourth pivoting axes respectively, wherein said latch mounting body and said main driving member, said securing member and said secondary driving member (collectively "members") are arranged as a four bar linkage with said securing member and said main driving member crossed over each other when said latch is in an unlocked position, and when in a locked position said latch mounting body and members form an over centre latch with said securing member located between said first and third pivot axes.

In another aspect the invention is a latch assembly to latch a second member or assembly relative to a first member or assembly ("latch mounting body or assembly"), such latch assembly comprising or including a latching arm ("securing member") pivoted at its proximal end to, or relative to, said latch mounting body or assembly and defining, with its distal end, a latching region ("engagement portion"), to latch the second member or assembly, and an actuating arm ("main driving member") pivoted at its proximal end to, or relative to, said latch mounting body or assembly and having its distal end actable about an arc of movement, said main driving member intermediately being pivoted to, or relative to, said securing member intermediate of said proximal end and said engagement portion of said securing member , thereby defining and allowing a scissoring pivot of the members, wherein rotation of said distal end of said main driving member on said arc of movement, by the application of force to an end region of said main driving member , causes a corresponding, but lesser, movement of the scissoring pivot, such that the angle defined by proximal pivots to the scissoring pivot is at least more obtuse or is obtuse, in a latching or locked condition, relative to a less obtuse angle, right angle or acute angle, when in a delatched or unlocked condition.

In another aspect the invention consists in, in combination or assembly, a hatch surround assembly and a hatch for the hatch opening defined by the hatch surround assembly, wherein there is a latching mechanism carried by the hatch adapted to latch or delatch from under part of the hatch surround assembly, that latching mechanism having; a latching arm ("securing member") proximally pivoted from, or relative to, said hatch, a distal region of said securing arm providing a latching region ("engagement portion"), and an actuating arm ("main driving member") proximally pivoted from, or relative to, said hatch , a proximal pivot of said securing member being further into said hatch than is the proximal pivot of said main driving member, said securing member and main driving member also being pivoted to, or relative to, each other so that they can scissor relative to each other, wherein a distal region of said main driving member has an arc of movement to correspondingly move, via said scissoring, the securing member between a latching or locked condition and a detaching or unlocked condition.

Preferably, in the latching condition the relative position of the pivots is such that they define from below an obtuse angle to the scissoring pivot and, in the delatched condition, a less obtuse angle, a right angle or an acute angle.

Preferably said hatch includes abutment features to limit the sweep of said distal region of said main driving member.

Preferably said hatch includes an opening or recess to allow tool access to said distal end region of said main driving member.

Preferably said hatch includes an opening or recess limits finger insertion to delatch the latching assembly.

Preferably said hatch is able to be engageable into the hatch opening assembly prior to its being located in its fully closed condition for latching, the latching assembly in that closed condition then complementing the affect of the initial hatch retaining engagement.

In yet a further aspect the present invention consists of a closure to at least in part close an opening to a sub-surface chamber, comprising or including, at least one hatch, a frame through which said sub-surface chamber can be accessed, said frame to receive and support said at least one hatch to thereby at least in part close off access to said sub-surface chamber, wherein there is at least one engagement of said hatch to said frame by an over-centre latch at one end of said hatch, and at an opposite end of said hatch there is at least i) one tongue on said hatch to under-engage a sprung member on said frame, or ii) one tongue on said frame to under-engage a sprung member on said hatch.

Preferably said frame is to lie above said sub-surface chamber. Preferably said over centre latch is on said hatch to under engage a retainment portion on said frame.

Preferably said retainment portion is on a second sprung member on said frame.

A method of providing a closure for a sub-surface chamber comprising or including the steps of, a) engaging a driving tool into an over-centre latch, to drive said over- centre latch to an unlocked position, said over-centre latch on either, i) a frame that defines, via an aperture therethrough, an access to said sub- surface chamfer, or ii) a hatch to at least in part close off said aperture, b) locating said hatch onto said frame, so that at one end said hatch under engages a spring member of said frame, or vice versa, c) locking said hatch to said frame, at an opposite end of said hatch, by moving said latch to a locked position by said driving tool.

Preferably said over centre latch is on said hatch.

Preferably said hatch is located onto said frame by use of said driving tool engaged in said over-centre latch and a further driving tool or tools engage apertures in said hatch to enable lifting and guiding of said hatch onto and off said frame.

Preferably prior to unlocking said latch a securement of said latch must be released.

Preferably said securement is a locking slide that prevents driving of said latch either or both by directly engaging said latch or parts thereof to prevent it actuating or indirectly to prevent insertion of said driving tool into said latch.

A kit or combination to provide a lockable hatch for a frame of a sub-surface chamber, said kit or combination comprising or including, a frame for a sub-surface chamber, a hatch for said frame to at least in part close an aperture defined by said frame, a latch removeably mounted or able to be removeably mounted to said hatch to retain said hatch to said frame, wherein said latch when mounted in said hatch or can be locked and unlocked by a tool, said tool retained by said latch when in the unlocked position to allow lifting of said hatch.

Preferably said kit or combination comes with said tool to lock and unlock said latch.

An over centre toggle latch to selectively secure a hatch to a frame of a subsurface chamber as herein described with reference to any one or more of the accompanying drawings.

A latch for a hatch as herein described with reference to any one or more of the accompanying drawings.

A hatch for closing a sub-surface chamber, wherein said hatch has a latch as herein described with reference to any one or more of the accompanying drawings.

A frame for a sub-surface chamber, wherein said frame has a latch as herein described with reference to any one or more of the accompanying drawings.

A closure for a sub-surface chamber as herein described with reference to any one or more of the accompanying drawings.

A method of providing a closure for a sub-surface chamber as herein described with reference to any one or more of the accompanying drawings.

As used herein the term "and/or" means "and" or "or", or both.

As used herein "(s)" following a noun means the plural and/or singular forms of the noun.

The term "comprising" as used in this specification means "consisting at least in part of. When interpreting statements in this specification that include that term, the features, prefaced by that term in each statement, all need to be present but other features can also be present. Related terms such as "comprise" and "comprised" are to be interpreted in the same manner.

This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements and features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

Preferred embodiments will now be described with reference to drawings, whereby;

Figure 1 is a perspective view of a latch of the present invention in the locked position,

Figure 2 is a similar view to Figure 1 with the addition that the driving tool has been fixed to the driving member and the lock is moved into an unlocked position by rotation of the driving member,

Figure 3 is a full drawing of the driving tool located in the unlocked latch,

Figure 4 is a series of drawings in isometric of,

A) the hatches secured in the frame that would normally be located above a subsurface chamber and defined an opening that is closeable by the hatches to the subsurface chamber;

B) shows the engagement of the driving tool with at least one of the latches of the hatch and the latch in the locked position,

C) shows the rotation of the driving tool and driving member of the latch to unlock the latch from the engagement with the frame;

D) shows the use of the driving tool engaged in the latch to lift the latch end of the hatch from the frame;

E) shows a similar view to (d) with the addition of extra tools engaged in the other end of the hatch, via keyholes, to allow its lifting from the frame; and

F) shows the hatches lifted clear of the frame together with an additional support member that runs in the middle of the frame to support the long free otherwise free edges of the hatches,

Figure 5 shows a close up of the frame and hatch in isometric with the driving tools engaged at either end of the hatch to guide the hatch away from or to the frame,

Figure 6 shows the hatch lifted clear of the frame,

Figure 7 shows a cross section along line AA of Figure 4(a) showing the frame with the hatch engaged at either end, at one end is a tongue under engagement of a sprung member and the other end is the latch engaging a sprung member of the frame, the access to the latch is initially covered by a latch cover,

Figure 8 shows the latch cover removed and the engagement of a driving tool with the driving member of the latch,

Figure 9 shows the rotation of the driving tool and driving member so that the driving tool under engages a lip or portion of the hatch and the driving member of the latch is removed from the locked position in Figure 8 to the unlocked position shown here, and the hatch is shown partially lifted clear,

Figure 10 is a series of drawings showing the unlocking of the latch in detail, where,

A) shows a cross section through a hatch in the frame indicating the locations of the tongue under engagement of the sprung member of the frame by the hatch and the location of the latch in the hatch engaging the frame,

B) shows Detail A of Figure 1OA in isometric with the additional security feature of locking slide to directly or indirectly block actuation of the main driving member, the slide guide and hold bolt that hold the locking slide in place and the lock preventing sliding action of the locking slide and the aperture and removable cover over the latch and the lock,

C) shows the same view as Figure 1OB in side cross section,

D) shows the second stage in unlocking the latch, whereby the removable covers are lifted and the lock is swung up to be unlocked, in this case the lock is a padlock unlocked with a key, and

E) shows the same view as Figure 1OD in side cross section,

Figure 11 is a series of drawings showing the actuating of the latch in detail, where,

A) shows the engagement of driving tool in the driving member of the latch,

B) shows Detail B of Figure HA with the additional security feature of the locking slide slid back to enable actuation of the main driving member by the driving tool, and

C) shows the same view as Figure HC in side cross section, Figure 12 shows the rotation of the driving tool and driving member to move the latch from the locked position to the unlocked position,

Figure 13 shows the use of the driving tool once engaged with the latch or and/or hatch to allow the driving tool to be used to lift the hatch at least partially clear of the frame,

Figure 14 shows a further cross sectional view of the hatch showing in detail the latch in its location relative to the hatch, and the lip or portion of the hatch that under engages the sprung member of the frame,

Figure 15 shows a hatch of Figure 14 in bottom isometric,

Figure 16 shows an isometric cross section of the hatch of Figure 15,

Figure 17 shows a bottom isometric view of a hatch showing in detail the latch and its connection to the hatch,

Figure 18 shows an underside of a frame including the retention member locations in the underside of the frame,

Figure 19 is an exploded isometric view of Figure 18 showing the retention members and the biasing members in this case as leaf springs that they retain,

Figure 20 is a side view of the latch of the present invention showing the tapered latch mounting body and threaded means for retaining the latch,

Figure 21 shows a bottom isometric view of hatch including the latch of the present invention, and

Figure 22 shows the same view as Figure 21 with the latch retaining member and latch exploded from the hatch.

A preferred embodiment of the present invention will now be described with reference to Figures 1 through 22.

A latch (1) is shown in Figure 1. The latch has a latch mounting body (5) and a main driving member (6). The main driving member (6) is pivoted from the latch mounting body (5) via a first pivot axis (7). The two extremes of movement of the main driving member (6) relative to the latch mounting body (5) are shown in Figure 1 and Figure 2. Pivoted from the latch mounting body (5) is a securing member (8), via a second pivot axis (11). In this embodiment the second pivot axis (11) is behind the first pivot axis (7) relative to the open part (22) of the latch mounting body (5). The securing member (8) is pivoted via the second pivot axis

(11) at its proximal end (10). The distal end (9) of the secure member (8) has an engagement portion (12). Toward the distal end (9) of the securing member (8) is pivoted to the secondary driving member (13) via the fourth pivot axis (16). The secondary driving member (13) is in turn pivo tally connected to the main driving member (6) via a third pivot axis (15). The third pivot axis (15) as seen is distal from the first pivot axis (7) of the main driving member (6). The resulting latch (1) has two positions, a locked position (18) as shown in Figure 1 and an unlocked position (17) as the shown in Figure 2.

In the locked position (18) the first line of action (65) formed between the third pivot axis (15), and fourth pivot axis (16) is parallel to or inclined at a acute angle to the second line of action (66) formed between the third pivot axis (15) and first pivot axis (7) shown in Figure 7. The first line of action (65) between the third pivot axis (15) and fourth pivot axis (16) is angled toward the engagement portion

(12) as shown. This alignment is angled toward or is parallel to the direction of loading (20) that the engagement portion (12) receives when the latch (1) is locked against a retaining portion (19). In the preferred embodiment the fourth pivot axis (16) when in the locked position (18) whilst still over third pivot axis (15) and between first pivot axis (7) and third pivot axis (15) lies slightly toward the engagement portion (12). In this way any loading of the engagement portion (12) will urge the driving member (6) or urge the latch (1) against its normal direction of operation, i.e. against the direction of unlocking. Therefore any loading of the latch (1) via the engagement portion (12) will actually cause the latch (1) to remain in its locked condition (18). The resulting assembly produces a four bar linkage (29) that has two of the linkages of the main driving member (6) and the securing member (8)) crossed when the other two members of the four bar linkage (29) (the latch mounting body (5) and the secondary driving member (13)) are near or substantially parallel to each other.

The main driving member (6) has a driving tool aperture (30) shown in Figure 2 and 7. This is to receive the driving tool (21). In the preferred embodiment such engagement is a circular aperture complementary to the lower portion of the driving tool (21). In the preferred embodiment this driving tool aperture (30) is located on the upper portion of the main driving member (6). In the preferred embodiment the driving tool aperture (30) is circular as is the lower end of the driving tool (21). There is also present a recess (31) to receive a cross member (32) of the driving tool (21). The use of this cross member (32) will be described below.

The driving tool (21) has a handle (33) at its end distal to the latch engaging end (34) as shown in Figure 3. In the preferred embodiment the handle (33) is perpendicular to the main body of the driving tool (21) to form a "T" handle. However it is to be appreciated that any other form of handle or portion on the driving member (21) that allows it to actuate the latch (1) as well as provide a surface for lifting is equivalent. In yet further embodiments there may be one tool (21) for unlocking the latch (1), another tool for engaging and subsequently lifting of the hatch via the latch (1). The driving tool (21) in other alternatives at its latch distal end may have a circular aperture or similar. In the preferred embodiment the driving tool (21) is made from resilient material such as steel or metal, but they also be made by other resilient materials such as for example, but not limited to, fiber reinforced plastics and other similar materials.

The components of the latch (1) are preferably made from steel whether by casting, forging, machining, molding or otherwise. In the preferred embodiment they are made from a 316 stainless steel that is cast. There may also be friction reducing interfaces, for example at the pivot points, and this falls within the scope of the invention.

In other forms of the present invention the components of the latch may be direcdy pivoted from the hatch (2) or frame (3), i.e. the latch mounting body is integral with the frame or hatch.

The frame (3) of the present invention defines an aperture (35) through its middle as shown in Figure 18. In die preferred embodiment the frame (3) is a continuous member defining the aperture (35). However in other embodiments there may only be the parts present required for engaging and supporting the hatch (2) and latch (1). For example, such components can be located within a concrete surround or footing that in turn defines the aperture (35). In yet other embodiments the frame (3) can be multi-component and may be bolted or otherwise joined together to define the aperture (35). Equivalents of such a frame will be apparent to a person skilled in the art.

The frame (3) may mount at least one latch (1) for engagement with a hatch (2). Alternatively the frame (3) may simply have a receiving portion, as a retained portion (19) to receive and engage the engagement portion (12) of the latch (1) as shown in Figure 7. In other words the latch could be present on either the frame (3) or the hatch (2) and the retainment portion (19) to engage the engagement portion (12) of the latch could be on the hatch or the frame respectively.

In the preferred embodiment the latch (1) is on the hatch (2) and the frame (3) has the receiving elements to engage with the latch (1) as shown in Figure 7.

Where the frame (3) is closed by more than one hatch (2) then a reinforcing member (36) is used to traverse the opening (35) of the frame (3) to provide additional support of the otherwise free sides of the hatches (2) as shown in Figure .4. If there are three or more hatches in a linear array then correspondingly there are two such reinforcing members (36) to support the free sides of the hatches (2).

The frame (3) in the preferred embodiment as stated has the retainment portion (19) to engage the engagement portion (12) of the latch (1) as shown in Figure 7. In the preferred embodiment the retainment portion (19) is on a sprung member (67A), such as a leaf spring (23). In other embodiments the sprung member (67A) may be formed from round bar or similar with elastic properties. The sprung member (67 A) whether of round bar or a leaf spring (23) can be retained to the frame (3) by a retaining member (37). The sprung member (67A) is located in an aperture (44) in the frame (3) as shown in Figure 18 and then the retaining member (37) is located over top of it to hold it in place. The retaining member (37) can be held in place in any one of a number of known ways, such as, but not limited to welding, threaded members, interference fit or similar. The result is that the sprung member (67A) is supported at either end and is able to be deflected at its middle portion by the engagement portion (12).

In the preferred embodiment the sprung member (67A) to engage with the latch (1) is partially biased in a downward direction relative to Figure 7. Thus when the latch (1) is moved to its locked position (18) the engagement portion (12) engages on the retainment portion (19) of the sprung member (67A) (in this example a leaf spring (23)) which in turn is biased upward as shown in Figure 7. In response the sprung member (67A) imparts a downward force (relative to Figure 7) on the engagement portion (12) of the latch. Due to the

centre nature of the latch as earlier described this forces the latch (1) to remain in the locked position (18). Due to the leverage ratio of the latch (1) and its members together with the driving tool (21) this spring force however is easily overcome. The biasing nature of the engagement between the engagement portion (12) and the retaining portion (19) also locates the hatch (2)securely in the frame (3) and prevents it moving out of the frame (3) even as parts wear.

In other embodiments the sprung member 67A, whether sprung or not, can be engaged directly or indirectly to the frame (3) by threaded means, or forging over part of the frame (3) engaged to the sprung member (67A). In yet other embodiments the sprung member (67A) may be engaged direcdy to the frame, e.g. by elastic engagement, for example by forcing over a dimple to retain the sprung member (67A) to the frame (3). In yet other forms of the invention the sprung member (67A) retaining portion (19) may be integrally formed with the frame (3). In yet other forms the sprung member (67A) and retaining portion (19) may be engaged with the frame (3) when the frame is formed, for example when the frame (3) is moulded or poured. In other embodiments of the present invention the reverse may occur whereby sprung member (67A) (such as, but not limited to, a leaf spring (23)) may be mounted to the hatch (2) in ways that are known, or described above and the latch (1) may be mounted to the frame (3). In other embodiments the latch may contain biasing element to be engaged on the frame, e.g. a leaf and spring on the latch.

The latch (1) in the preferred embodiment is retained to the hatch (2) via its tapered latch mounting body (5) and a retention stud (43). A nut (71), preferably a lock nut, holds the stud in place to the frame.

In other embodiments a hold bolt (76) such as shown in Figure 1OE may pass up through the main latch body (5) to retain the latch to the frame (2). A tapered cavity (69), that opens toward the periphery of the hatch (2), is formed to receive the latch (1).

The latch (1) is slid into the tapered cavity (69) and the retention stud (43) passes through the back wall of the tapered cavity (69) via an aperture therethrough as shown in Figure 22. The nut (71)is then run up on the retention stud (43) to pull the latch (1) into the tapered cavity (69) and lock it there. Alterantively the hold bolt (76) is then passed through the main latch body (5) to retain it to the frame as shown in Figure 1OE. In this way the latch (1) is easily replaceable as need be, for example due to damage or wear.

The latch retainer (45) can be engaged to the hatch in any one of a number of known ways such as above. In the preferred embodiment it is retained by welding or threaded fasteners. The latch retainer (45) has guide portions (49A) to locate with complementary guide portions (49B) in the tapered cavity (69) in the hatch (1) as shown in Figure 22. The latch retainer (45) preferably has protection legs (47) to protect the latch members when the hatch (1) is not in the frame (3), for example the hatch (1) is resting on the ground.

In the preferred form of the present invention the latch (1) is at one end of the hatch (2) as shown in Figure 7. At the opposite or other end of the hatch (2) there are complimentary engagement portions of the hatch (2) to the frame (3). In the preferred form of the invention these complimentary engagement portions consist of a tongue (38) that under engages into a lip or pocket (39). In the preferred form of the invention the surface of the lip or pocket (39) that engages the tongue (38) is sprung or biased, for example by a leaf spring (23). In other embodiments any form of elastic material may be present, including as described for the latch, an elastic rod or similar. The tongue (38) or a lower portion thereof, engages a surface or point (40) to drive the tongue (38) up into pocket (39).

In the preferred embodiment the tongue (38) is mounted at the other end of the hatch (2) and the lip or pocket (39), arranged to coincide with the tongue (38), is on the frame (3) as shown in Figures 7 and 19. In this preferred embodiment there is a fulcrum surface or point (40) to engage a lower surface or extension thereof, of the tongue (38). The result is that when the tongue (38) is pivoted into location to engage the lip or pocket (39) the upper surface of the tongue (38) is driven upward to bear against the engaging portion of the lip or pocket (39). Thus in the preferred embodiment where the engaging surface of the lip or pocket (39) is a sprung member, such as leaf spring (23) or elastic rod stock as above, then a spring force is loaded onto the tongue (38) to hold the hatch (2) into the frame (3). In this case the fulcrum point causes the tongue (38) to bias the sprung member upwards. The sprung member is retained to the frame in a similar way as described above with a retaining member (37) holding the sprung member in an aperture (44).

There may be hatch guides (50A) shown in Figure 18 on the hatch (3) outer periphery that are complimentary to frame guides (50B) on the inner periphery of the frame (3). These guides are towards the non-latched end of the hatch (1) to guide the hatch and help the tongues (38) engage the lip or pocket (39) and aid engagement of the fulcrum surface (40).

The result is that when the hatch (2) is located in the frame (3) and the latch

(1) is locked the hatch is positively forced into or onto the frame by the biasing against the tongues (38) and the latch (1) by the various sprung members (67A) and (67B).

In other forms of the present invention the lip or pocket (39) may be made or resilient material and it is the tongue (38) that is the elastic material and is deflectable downward by the lip or pocket (39). The preferred embodiment has the hatch (2) having the tongue (38). This is useful since when the hatch (2) is clear of the frame

(3) and its aperture (35) there are no extraneous protrusions into the aperture (35), thus giving as clean an access through the aperture (35) to the subsurface chamber

(4) as possible.

The tongues (38) may be formed integrally with the hatch (2) or frame (3) (whichever they are locating on) such as when they are formed during manufacture. In alternative versions the tongues (38) may be items that are located on the hatch

(2) or frame (3) (whichever they are located on) after its manufacture and may be replaceable items. Such replaceable tongues (38) may allow for breakage and/or wear over time. Similarly the engaging surface of the lip or pocket (39) may be replaceable, such as for example when it is a leaf spring (23). Shown in Figure 7 is a removable cover (28) that covers the latch (1). The removable cover (28) gives a smooth upper surface to the hatch when the latch is not in use. It also prevents damage to the latch when not in use.

A way of securing the latch (1) will now be described with reference to Figures 10 to 1OE, HB and HC. Towards the interior of the hatch (2) and below the main surface of the hatch (3) there is a locking slide (73). This is held in place by a slide plate (77). This slide plate (77) is in turn held in place by hold bolt (76). The hold bolt (76) in this embodiment passes through a bigger version of die retention stud (43) and aids to hold the latch mounting body (5) to the hatch (3).

The hold bolt (76) locks the slide plate (77) securely in place. The slide plate in turn acts as a guide for the locking slide (73). The hold bolt (76) passes through a slot (80) in the locking slide (73). In this way the locking slide is free to slide back and forth toward and away from the main driving member (6) between the lower surface of the hatch (2) and the upper surface of the slide plate (77) and is guided in extent by the hold bolt (76).

When the locking slide (73) is towards the main driving member (6) is capable of preventing actuation or rotation of the main sliding member (6) either directly or indirectly. It can be capable of preventing rotation of the main driving member directly because the latch most tip of die locking slide can lie either in the driving tool aperture (30) (in the preferred embodiment) or another aperture in the main driving member. In this way the main driving member is prevented from rotating because the locking slide bears direcdy on it.

In an indirect way the locking slide (73) can prevent rotation of the main driving member (6) by blocking access of tooling to the main driving member (6) and so thus preventing its actuation.

In the preferred embodiment the locking slide both acts direcdy by locking the main driving member from rotating, and indirectiy by blocking access of tooling to the main driving member.

The locking slide when engaged as above so as to prevent actuation of the main driving member has an aperture (81) at its latch distal end that is aligned with a corresponding aperture (82) in the slide plate (77). These aligned apertures (shown aligned in Figure 1OE allow the passage therethrough of a locking member, such as the shackle of a pad lock (75).

Thus by the use of the locking slide (73) and a suitable lock (75) the latch can be locked in the locked position. Thus the hatch can be locked to the frame.

A second removable cover (28B) covers the aperture where the lock (75) may Ue.

Whilst here the lock (75) is shown in the hatch, it can equally be located in the frame along with the latch (1) as earlier described. Also whilst here the locking slide (73) is shown as moving perpendicular to the edge of the frame (3) and hatch (2) in the horizontal plane, it can just as easily move parallel to the edge of the frame (3) and the hatch (2).

There may be one such locking mechanism per latch (1) or only one per hatch (2) or as many as required.

A third aperture (83), shown in Figure HC, may be present in the locking slide (73) also so the locking slide can also be locked in an open position free of locking the latch (1) as shown in Figure HC — though no lock is shown in place here.

The removable covers (28) and (28B) may be retained in place by gravity, clip in place, or may be sprung loaded.

In the preferred embodiments the removable covers lie in recesses in the hatch (2) as shown in Figure 10 so they lie flush with the upper surface of the hatch (2).

The method of use of the present invention will now be described with reference to Figures 4 to 6. The frame (3) is located and secured (or the parts forming the frame (3)) on or about a subsurface chamber (4) to define an aperture (35) for access to the subsurface chamber. Hatches (2) are engaged therein to close off the access. The removable cover (28) must be removed prior to engagement thereof by the driving tool (21).

With reference to Figures 1OB throughlOE and HB and HC the removable cover (28B) over the lock (75) is lifted and the lock (75) is unlocked, for example by a key. The part of the lock (75) securing the locking slide (73) is removed and the locking slide (73) is slide back away from the main driving member (6) to allow access or tooling and rotation of the main driving member.

When the hatch or hatches (2) need to be removed then a driving tool (21) is engaged in the driving tool aperture (30), and the driving tool is rotated about the first pivot access (7). In the embodiment shown in Figure 4 this is a rotation of the driving tool (21) to or toward the frames (3). This unlocks the latch (1) from the frame (3). Thereafter (or before) further driving tools (21B) as described are located and locked into keyholes at the other end of the frame (2) that is the tongue (38) end. These keyhole apertures may have an elongate slot either side of an aperture to receive the engaging end (24) of the further driving tool (21B) such that rotation of the driving member (21) to be an aligned position as shown in Figure 4(e) then moves the cross member (32) to a point where it cannot disengage from the aperture in the hatch (2). In other embodiments the further driving tools (21B) may have other known forms of complimentary engagement within the hatch (2) to help removing the hatch (2). . .

Once the driving member (21) and further driving members (21B) are engaged in the latch (1) the latch end of the hatch (2) can be lifted clear of the frame (3) by driving member (21). By use of^'the further driving tools (21B), or standard known keyhole engagement tools, at the other end of the hatch (2) the other end of the hatch (2) can be pivoted and lifted clear of its engagement with the frame (3). Thereafter the hatch (2) can be moved away to reveal the aperture (35) for access to the subsurface chamber (4), or replacement of the hatch or for whatever reason the hatches needed to be removed from the frame.

To replace the hatch (2) in the frame (3) the steps above are simply reversed and the locking slide (73) deployed in place again to block rotation of the latch (1).

In ways known in the art the hatch (2) has a surface or surfaces that are downwardly directed to engage upwardly directed support surfaces of the frame (3). In this way the hatch (2) is supported and prevented from moving through the frame (3). The present invention may be supplied as a separate frame (3) and hatch (2). Alternatively it may be supplied as a kit or assembly or a combination of frame (3) and hatch or hatches (2).

The foregoing description of the invention includes preferred forms thereof. Modifications may be made thereto without departing from the scope of the invention.

Claims

1. A latch to selectively secure a hatch to a frame of a sub-surface chamber, comprising or including, a latch mounting body, from which is pivotally mounted, a main driving member to pivot about a first pivot axis relative to said latch mounting body, and a securing member with a proximal end and a distal end, said securing member pivoted relative to said latch mounting body by a second pivot axis at or toward said proximal end, said distal end having an engagement portion, and a secondary driving member extending between and pivotally engaged i) at or towards an end of said main driving member distal from said first pivot axis, at a third pivot axis, and ii) to said securing member via a fourth pivot axis intermediate of said distal end and said second pivot axis, wherein said latch has an unlocked position wherein said engagement portion is free of a retainment portion of, a) said frame when said latch is mounted to said hatch, or b) said hatch when said latch is mounted to said frame, and a locked position wherein said engagement portion can retain said latch to said retainment portion, said latch in said locked position has, said third pivot axis and said fourth pivot axis aligned in a line at least substantially parallel to, or inclined at an acute angle to (toward said engagement portion) a line between said first pivot axis and said third pivot axis, with said fourth pivot axis lying between said first pivot axis and said third pivot axis.

2. A latch as claimed in claim 1 wherein said latch is located in or on said hatch to engage and selectively retain said hatch to an at least in part hatch surround or frame.

3. A latch as claimed in either of claims 1 or 2 wherein said latch is moved between said locked and unlocked position by a driving tool engaging with and rotating said main driving member.

4. A latch as claimed in any one of claims 1 to 3 wherein said mounting body is U shaped in plan view, the open part of the U shape oriented towards said retainment portion.

5. A latch as claimed in any one of claims 1 to 4 wherein said retainment portion is sprung loaded against the engagement of said engagement portion.

6. A latch as claimed in any one of claims 1 to 5 wherein said retainment portion is a leaf spring biased against said engagement portion when in said locked position.

7. A latch as claimed in any one of claims 1 to 5 wherein said retainment portion is a sprung bar retained at either end.

8. A latch as claimed in any one of claims 1 to 7 wherein said latch when moving toward said locked position loads against said retainment portion to pull said hatch into or onto said frame.

9. A latch as claimed in any one of claims 3 to 8 wherein said driving tool is an elongate member with a handle distal to its main driving member engaging end.

10. A latch as claimed in any one of claims 3 to 9 wherein said driving tool can also engage said hatch to facilitate it being lifted from said frame.

11. A latch as claimed in any one of claims 3 to 10 wherein said driving tool is not removable from said latch when said latch is in said unlocked position.

12. A latch as claimed in any one of claims 3 to 11 wherein said driving tool under-engages a portion of said latch mounting body or said hatch when in said unlocked position to prevent its removal from said driving member.

13. A latch as claimed in any one of claims 1 to 12 wherein contact surfaces of said retainment portion and said engagement portion lie in a plane that is substantially horizontal.

14. A latch as claimed in any one of claims 1 to 13 wherein said engagement portion under-engages said retainment portion when in said locked position.

15. A latch as claimed in any one of claims 1 to 14 wherein said locked condition said latch is covered by a removable cover.

16. A latch as claimed in claim 1 wherein said pivot first, second, third and fourth axes are parallel to one another.

17. A latch as claimed in any one of claims 1 to 16 wherein said latch can be secured to prevent its actuation.

18. A latch as claimed in any one of claims 1 to 17 where said latch can be secured in said locked position via a locking slide that prevents; a) rotation of said main driving member by either or both by i) directly engaging said main driving member, or ii) indirectly by preventing engaging of tooling into said main driving member to rotate it.

19. A latch to selectively secure a hatch to a frame of a sub-surface chamber, comprising or including, a latch mounting body, a main driving member, pivoted from a first pivot axis from said latch mounting body, a securing member, pivoted from a second pivot axis from said latch mounting body, and a secondary driving member pivoting between distal ends of said main driving member and said securing member via third and fourth pivoting axes respectively, wherein said latch mounting body and said main driving member, said securing member and said secondary driving member (collectively "members") are arranged as a four bar linkage with said securing member and said main driving member crossed over each other when said latch is in an unlocked position, and when in a locked position said latch mounting body and members form an over centre latch with said securing member located between said first and third pivot axes.

20. A latch assembly to latch a second member or assembly relative to a first member or assembly ("latch mounting body or assembly"), such latch assembly comprising or including, a latching arm ("securing member") pivoted at its proximal end to, or relative to, said latch mounting body or assembly and defining, with its distal end, a latching region ("engagement portion"), to latch the second member or assembly, and an actuating arm ("main driving member") pivoted at its proximal end to, or relative to, said latch mounting body or assembly and having its distal end actable about an arc of movement, said main driving member intermediately being pivoted to, or relative to, said securing member intermediate of said proximal end and said engagement portion of said securing member , thereby defining and allowing a scissoring pivot of the members, wherein rotation of said distal end of said main driving member on said arc of movement, by the application of force to an end region of said main driving member , causes a corresponding, but lesser, movement of the scissoring pivot, such that the angle defined by proximal pivots to the scissoring pivot is at least more obtuse or is obtuse, in a latching or locked condition, relative to a less obtuse angle, right angle or acute angle, when in a delatched or unlocked condition.

21. In combination or assembly, a hatch surround assembly and a hatch for the hatch opening defined by the hatch surround assembly, wherein there is a latching mechanism carried by the hatch adapted to latch or delatch from under part of the hatch surround assembly, that latching mechanism having; a latching arm ("securing member") proximally pivoted from, or relative to, said hatch, a distal region of said securing arm providing a latching region ("engagement portion"), and an actuating arm ("main driving member") proximally pivoted from, or relative to, said hatch , a proximal pivot of said securing member being further into said hatch than is the proximal pivot of said main driving member, said securing member and main driving member also being pivoted to, or relative to, each other so that they can scissor relative to each other, wherein a distal region of said main driving member has an arc of movement to correspondingly move, via said scissoring, the securing member between a latching or locked condition and a detaching or unlocked condition.

22. In combination or assembly, a hatch surround assembly and a hatch for the hatch opening defined by the hatch surround assembly as claimed in claim 21 wherein in the latching condition the relative position of the pivots is such that they define from below an obtuse angle to the scissoring pivot and, in the delatched condition, a less obtuse angle, a right angle or an acute angle.

23. In combination or assembly, a hatch surround assembly and a hatch for the hatch opening defined by the hatch surround assembly as claimed in either of claims 21 or 22 wherein said hatch includes abutment features to limit the sweep of said distal region of said main driving member.

24. In combination or assembly, a hatch surround assembly and a hatch for the hatch opening defined by the hatch surround assembly as claimed in any one of claims 21 to 23 wherein said hatch includes an opening or recess to allow tool access to said distal end region of said main driving member.

25. In combination or assembly, a hatch surrounded assembly and a hatch for the hatch opening defined by the hatch surrounded assembly a claimed in claim 24 wherein said opening or recess limits finger insertion to delatch the latching assembly.

26. In combination or assembly, a hatch surround assembly and a hatch for the hatch opening defined by the hatch surround assembly as claimed in any one of claims 21 to 25 wherein said hatch is able to be engageable into the hatch opening assembly prior to its being located in its fully closed condition for latching, the latching assembly in that closed condition then complementing the affect of the initial hatch retaining engagement.

27. A closure to at least in part close an opening to a sub-surface chamber, comprising or including, at least one hatch, a frame through which said sub-surface chamber can be accessed, said frame to receive and support said at least one hatch to thereby at least in part close off access to said sub-surface chamber, wherein there is at least one engagement of said hatch to said frame by an over-centre latch at one end of said hatch, and at an opposite end of said hatch there is at least i) one tongue on said hatch to under-engage a sprung member on said frame, or ii) one tongue on said frame to under-engage a sprung member on said hatch.

28. A closure as claimed in claim 27 wherein said frame is to lie above said subsurface chamber.

29. A closure as claimed in either of claims 27 or 28 wherein said over centre latch is on said hatch to under engage a retainment portion on said frame.

30. A closure as claimed in claim 29 wherein said retainment portion is on a second sprung member on said frame.

31. A method of providing a closure for a sub-surface chamber comprising or including the steps of, a) engaging a driving tool into an over-centre latch, to drive said over- centre latch to an unlocked position, said over-centre latch on either, i) a frame that defines, via an aperture therethrough, an access to said sub-surface chamfer, or ii) a hatch to at least in part close off said aperture, b) locating said hatch onto said frame, so that at one end said hatch under engages a spring member of said frame, or vice versa, c) locking said hatch to said frame, at an opposite end of said hatch, by moving said latch to a locked position by said driving tool.

32. A method as claimed in claim 31 wherein said over centre latch is on said hatch.

33. A method as claimed in claim 32 wherein said hatch is located onto said frame by use of said driving tool engaged in said over-centre latch and a further driving tool or tools engage apertures in said hatch to enable lifting and guiding of said hatch onto and off said frame.

34. A method as claimed in claims 31 to 33 wherein prior to unlocking said latch a securement of said latch must be released.

35. A method as claimed in claim 34 wherein said securement is a locking slide that prevents driving of said latch either or both by directly engaging said latch or parts thereof to prevent it actuating or indirectly to prevent insertion of said driving tool into said latch.

36. A kit or combination to provide a lockable hatch for a frame of a sub-surface chamber, said kit or combination comprising or including, a frame for a sub-surface chamber, a hatch for said frame to at least in part close an aperture defined by said frame, a latch removeably mounted or able to be removeably mounted to said hatch to retain said hatch to said frame, wherein said latch when mounted in said hatch or can be locked and unlocked by a tool, said tool retained by said latch when in the unlocked position to allow lifting of said hatch.

37. A kit or combination as claimed in claim 36 wherein said kit or combination comes with said tool to lock and unlock said latch.