Patent Description:
The subject type of well covers can be found with different types of wells such as surface water wells, drainage wells, manholes etc..

The invention is however not to be limited for use in a specific type of well but can be applied to any well which is arranged with fixed well cover as well as telescopically movable and floating well covers. Arrangements of the present invention are also not limited for use in wells of a specific sectional shape, but can be applied to rectangular as well as to circular wells and well pipes.

However, an arrangement of the present invention is especially suited for inside telescopic installation in an upright well pipe. Additionally, the arrangement of the present invention is especially suited for post-installation in existent well pipes.

Whether produced in cast iron, tempered iron or steel, the subject well cover lids hold a considerable weight, usually in the range of <NUM>-<NUM> or more, and the handling of well cover lids in installation and maintenance is a heavy work, and associated with a risk of clamping injury for the worker as well.

However, the present invention can be applied also to well pipes and well lids made of cement.

Several attempts to assist in the lifting and lowering of well cover lids are disclosed in the patent literature.

<CIT> and <CIT> are two examples on the use of gas cylinders for upwards swinging of a well cover lid which is pivotally anchored to a well cover frame. A drawback with this kind of solution is that a hinged connection which is disposed outside the periphery of the well cover lid requires some installation space inside or outside of the well cover frame. Another drawback is that post-installation requires substitution of the whole well cover including the well cover lid and well cover frame.

<CIT> and <CIT> are two examples on the use of a biased helical pressure spring for lifting a well cover lid from a well cover frame, whereupon the well cover lid in a lifted state can be swung to the side in a horizontal plane by pivoting about a guide rod or bolt which runs vertically through the helical spring, and which is slidably received or screwed into the well cover frame. A drawback with this kind of solution is that the power of the spring is predetermined and constant whereas the required power for lifting can vary and be influenced by, inter alia, ice formation or dirt that gets trapped between the lid and the well cover frame.

<CIT> discloses an arrangement for lifting a lid for a manhole. This arrangement comprises a housing arranged on the exterior of a well cover frame. The lower end of a bolt, threaded on the outside, is pivotally anchored in the bottom of the housing. A head end of the bolt (square-headed) is available for engagement with a turning tool via a hole through the lid, located in a portion of the lid which projects radially outside the otherwise circular periphery of the lid. An upper end of a hollow sleeve, which is slidably received in the housing, is attached to a downwards facing side of said radially projecting portion of the lid. An internally threaded hole through a radial constriction in the sleeve is in threaded engagement with the bolt that runs through the sleeve. As the bolt is turned for lifting or lowering of the lid, the said sleeve moves axially on the bolt which is anchored in the housing.

A drawback with this kind of solution is that the head end of the bolt descends continuously deeper down into the sleeve as the sleeve climbs upwards along the bolt, upon lifting of the lid. This effect may obstruct the engagement with the tool.

Another drawback is that the lid and the sleeve cannot be separated from the housing in the course of exchanging the lid, since a tool for the square-head cannot be passed through the internally threaded hole in the sleeve. Neither is this disclosed solution suitable for implementation with floating well covers having a well cover frame that is telescopically movable in a well pipe.

<CIT> discloses a well cover lid resting by gravity on a flange formed in a well opening. A threaded bolt is arranged to engage upon rotation, after a length of dead travel, the lower side of the well cover lid for lifting the well cover lid by further rotation of the bolt. In lowering, the well cover lid follows the bolt passively until it again comes to rest on the flange. There is thus no positive connection between the well cover lid and the threaded bolt, and no positive locking between the well cover lid and the well opening.

According to current practise, a well cover lid at a weight of more than <NUM> is considered being locked to the well cover frame in effect of its weight. To open the lid, an essentially conventional iron bar is used and inserted in a notch formed in the upwards facing side of the lid, whereupon the lid can be levered upwards far enough to permit gripping of the edge of the lid by hand.

Lighter well cover lids can include a locking function in the form of a bolt going through the lid and screwed into the well cover frame. This screw is accessible in the upper side of the lid and is typically formed with a countersunk cone head having a groove for a conventionally shaped screw driver.

Lighter well covers may alternatively include a locking function in the form of a spring-biased locking latch which is arranged in the downwards facing side of the lid, engaging a heel or recess which is formed in the well cover frame. The locking latch can be moved out of the locking engagement by means of an iron bar which is inserted via a hole through the lid.

It is a drawback with the named locking functions that the well cover lid can be opened using a conventionally designed tool, and that an unauthorized opening of the lid does not result in visible damage to the lid.

The invention aims at providing an arrangement for a well cover, comprising a lifting and lowering device which is lacking the drawbacks mentioned above.

One object of the invention is to provide an arrangement for a well cover comprising a lifting and lowering device which can be afterwards installed in existent wells.

Another object of the invention is to provide an arrangement for a well cover comprising a lifting and lowering device arranged for simplified substitution of the well cover lid.

Still another object of the invention is to provide an arrangement for a well cover comprising a lifting and lowering device with integrated locking function.

One or more of these objects is met through an arrangement designed in accordance with claim <NUM>.

Briefly, the invention provides an arrangement for a well cover, the arrangement comprises a lifting and lowering device which is mountable or attached to the inner side of a well opening, the lifting and lowering device arranged for lifting and unlocking, or for lowering and locking respectively, of the well cover lid in relation to the well opening. The arrangement comprises a housing inside of which is accommodated a stationary and non-pivotally anchored nut having an internally threaded hole for a bolt with an external thread going through the nut, a piston carried on the bolt and slidably received in the housing, wherein an upper end of the piston is configured for supporting the well cover lid while simultaneously an upper end of the bolt projects above the upper end of the piston to be accessible for engagement with a turning tool via a hole that opens in the upwards facing side of the well cover lid at a location inside of the periphery of the well cover lid when the housing is attached to an inner side of a well opening, whereby the well cover lid is forced by the piston to follow the axial displacement of the bolt, upwards or downwards, as the bolt is turned under threaded engagement with the nut.

According to the present invention, the hole through the well cover lid comprises an opening of a first diameter mouthing in the upwards facing side of the well cover lid, said opening via a radial shoulder continuing in a lead-through of a second diameter which is smaller than the first diameter. A clamping ring is mountable on the bolt and in mounted position abutting the radial shoulder which connects the first and second diameters of the hole. The clamping ring provides the technical effect and advantage of additionally preventing unauthorized removal of the well cover lid.

A technical effect and advantage is hereby provided in that the tool interface in the upper end of the bolt is always equally accessible for engagement with a turning tool, regardless of vertical height position of the well cover lid in lifting and lowering operations.

Another technical advantage is that the arrangement of a lifting and lowering device as claimed permits pre-assembly and installation upon manufacture of the well, as well as post-installation in existent wells. The claimed solution facilitates exchange of well cover lids, and can be installed in telescopic "floating" well covers as well as in connection with fixed well covers if appropriate.

By turning movement around the bolt, the well cover lid can in lifted position be swung to the side in the horizontal plane so as to provide access to the well. Access to the well for maintenance work is hereby substantially simplified and the previous heavy work in order to move the lid away from the well is avoided, as is also the risk of injury by clamping under the heavy lid.

In the lowered position, the well cover lid is secured to the well opening in result of the engagement between the nut and the threaded bolt.

In one embodiment, an upper end of the bolt is shaped for turning engagement only with a tool which is shaped specifically for this purpose. An advantage with this embodiment is that readily available conventional tools cannot provide access to the well.

In one embodiment, the piston is rotationally supported on the bolt by means of a thrust bearing which supports from below a supporting block forming the upper end of the piston. An advantage of this embodiment is that thrust bearings, such as axial/radial roller bearings, are able to accommodate great loads while provide low friction rotation. In the claimed solution, the capacity of thrust bearings is utilized for carrying the total weight of the well cover lid, supporting block and cylinder to the bolt.

In one embodiment, the nut is anchored in an upper end of a cylinder which is anchored in a bottom of the housing, and from there reaches upwards concentrically inserted between the bolt and the cylindric sleeve which forms part of said piston. This embodiment ensures the stationary fixed installation of the nut in the lifting and lowering device.

Advantageously, the cylinder is anchored in the bottom of the housing by means of a threaded engagement. The embodiment facilitates assembly.

In one embodiment, the sleeve is slidably journaled, by means of a slide bearing, inside of a cylinder wall forming the housing. The embodiment provides a compact design resulting in reduction of building space requirement in the well opening.

In one embodiment, the slide bearing is a self-lubricating bushing, preferably made of alloy metal. The embodiment ensures long service time without need for maintenance.

In one embodiment, the piston is attached to the well cover lid through a threaded engagement. The embodiment provides simplified dismounting and exchange of well cover lids simply by unscrewing the lid from the piston.

In one embodiment, the opening of the hole is widened to provide a cleaning groove in the upwards facing side of the well cover lid. The embodiment facilitates removal of foreign material from the tool interface/bolt head.

In one embodiment the bolt is made of stainless steel and comprises a trapezoidal thread. This embodiment provides dual technical effects and advantages: the stainless-steel bolt remains unaffected by weather conditions, and the trapezoidal thread reduces the force required for turning the bolt. In this connection it serves to mention that a <NUM> lid can be easily lifted and lowered by means of a small <NUM> V battery powered drill.

In one embodiment, the housing is formed integrally with a well. In cast iron products, this embodiment reduces mounting work and material.

In one embodiment, the bottom of the housing comprises a drainage hole.

In one embodiment, a removable plug is arranged to cover the cleaning groove between service occasions.

In a second aspect of the invention, a well cover for a metal or cement casted well opening is provided including the lifting and lowering device of the claimed arrangement.

Other embodiments and features of the invention will appear in detail from the description given below.

Embodiments of the invention will be explained below with reference made to the accompanying schematic drawings, of which.

It serves initially to explain that definitions with respect to position and direction as used in the description and claims are related to a substantially horizontal orientation of well cover lid and well cover frame. It shall also be explained that the expressions "lid" and "well cover lid" shall be seen as alternative expressions for one and the same element, and that the word "frame" is used synonymously with the expression "well cover frame". In similar way, the expressions "upwards facing side" and "upper side", or "downwards facing side" and "lower side" respectively, are alternatingly used to define the two sides of the well cover lid.

With reference made to <FIG> and <FIG>, a well cover is shown comprising a well cover frame <NUM> and a disc-shaped well cover lid <NUM> connectable to the frame. The well cover frame and well cover lid may be made of metal such as cast iron, steel or light metal, as appropriate. In cement casted wells the well cover frame <NUM> may form an integral part of an upper rim area of a cement pipe, however, for the purpose of this disclosure, the entrance and opening of the well is here shown to be lined with a separate well cover frame.

The well cover lid <NUM> can be lowered and received by a shoulder <NUM> that runs around the upper end of the well cover frame. A guide determining the rotational position of the lid in the well cover frame may be formed in the lid and the well cover frame, and arranged in the form of a guiding groove <NUM> and a guiding heel <NUM> which can be received in the groove. The guiding groove and the guiding heel are preferably arranged with correspondingly shaped, upwards tapering contact surfaces of which two, a and b, can be facing the circumferential direction of the lid whereas an intermediate contact surface c is facing the radial direction, towards the centre of the well cover lid.

For the purpose of interaction with a lifting and lowering device, which will be more closely described below, the well cover lid <NUM> is formed with a through hole located at a distance inside of the periphery <NUM> of the well cover lid. This hole has an opening <NUM> mouthing with a first diameter in the upwards facing side of the lid, the hole passing a radial shoulder <NUM> into a lead-through <NUM> of a second, smaller diameter. In the upper side of the well cover lid, the mouth <NUM> of the hole is widened and forming a cleaning groove <NUM> arranged to facilitate removal of dirt and ice from the opening <NUM>. A removable plug <NUM> may be arranged to cover the hole and the cleaning groove between maintenance works.

A supporting block <NUM> having a through hole <NUM> which is concentrically aligned with the hole <NUM>, <NUM>, <NUM> is attached to the downwards facing side of the well cover lid <NUM>. A cylinder-shaped sleeve <NUM> depends from the supporting block <NUM>, in that an upper end of the sleeve is fixedly anchored in the supporting block <NUM>. The supporting block and the sleeve, which can be integrally formed or joined together through welding or by other suitable means, form in cooperation a piston <NUM>, <NUM> for lifting the lid <NUM> in a manner which will be explained below. The piston <NUM>, <NUM> is slidably and telescopically received between the wall of a cylindrical housing <NUM> and a cylinder <NUM> which is standing upright in the sleeve <NUM>. In its lower end, the cylinder <NUM> is axially and non-rotationally anchored in a bottom member <NUM> of the housing <NUM>. The anchoring of the cylinder <NUM> in the housing <NUM> may advantageously include a threaded connection <NUM>.

A nut <NUM> is non-rotationally and fixedly anchored in the upper end of the cylinder <NUM>. The nut <NUM> has a hole internally threaded for engagement with the threads of a through-going, externally threaded bolt <NUM>. The threads on the bolt and the nut may advantageously be realized as trapezoidal threads. A non-threaded length in the upper end of the bolt forms a neck <NUM> which reaches through the supporting block <NUM> and through the lead-through portion <NUM> in the well cover lid. In the upper end of the neck <NUM>, the bolt is formed with a head <NUM> which is shaped for engagement with a tool adapted for turning of the bolt <NUM>.

The head <NUM> may be shaped as a square head or a hexagon head which is properly dimensioned for operative engagement with a tool that is dimensioned for this purpose.

In an alternative embodiment, the head <NUM> is formed for operative engagement with a special tool which is formed for this purpose only. By way of the disclosed embodiment, e.g., the head <NUM> may be arranged with a tool interface of known kind which is found in locking bolts or locking nuts, including axially running grooves or ribs formed on a circular head periphery. The head <NUM> may alternatively include a locking nut which has to be removed with help from a special tool in order to expose a tool engagement interface in the upper end of the bolt <NUM>.

In the area of the upper end of the neck portion <NUM>, a clamping ring <NUM> is inserted under tension in a groove formed in the exterior of the bolt. In its inserted position, the clamping ring <NUM> rests from above on the radial shoulder <NUM> in the hole <NUM>, <NUM>, <NUM>. In the area of a lower end of the neck <NUM>, a thrust bearing <NUM> is axially arrested but rotationally supported on the bolt <NUM>. The thrust bearing <NUM> supports the supporting block <NUM> from below, the thrust bearing <NUM> carrying the total weight of the well cover lid <NUM>, the supporting block <NUM> and the sleeve <NUM>.

From the above said it will be appreciated that the bolt <NUM> is moved upwards from the nut <NUM> when the bolt is turned in one direction, whereas turning in the opposite direction causes the bolt <NUM> to move downwards in the nut. The piston <NUM>, <NUM> and the well cover lid <NUM> follow slavishly the movements of the bolt in the directions of the double arrow F. Accordingly, the position of the head <NUM> in the upper side of the lid remains the same independent of the vertical location of the lid. In lifted position, the well cover lid <NUM> may be swung to the side in a horizontal plane by turning the lid around the neck <NUM>.

It will also be appreciated, that a damaged well cover lid can be lifted off from the bolt, together with the piston <NUM>, <NUM>, simply by removing the clamping ring <NUM>. Unauthorized access to the well can be prevented or discovered if the above-mentioned plug <NUM> is arranged with a locking function which has to be destroyed before the plug can be removed, in case the proper key is unavailable. The plug <NUM> may be of disposable type, e.g., and arranged to be destroyed or broken upon removal to provide access to the bolt head <NUM>.

Assembling the arrangement can be accomplished in the following way: firstly, the housing <NUM> is attached to the inner side wall of the well cover frame, where after the cylinder <NUM> with the nut <NUM> is screwed from above into the bottom <NUM> of the housing. Next, the bolt <NUM> is screwed into the nut <NUM> from below, where after the thrust bearing <NUM> is inserted on the bolt <NUM> from above. In the next step, the sleeve <NUM> is brought to slide down the exterior of the cylinder <NUM> from above until the supporting block <NUM> rests onto the upper side of the thrust bearing <NUM>. Then finally, the well cover lid <NUM> can be joined from above with the supporting block <NUM>, such as through a threaded engagement between an external thread on the supporting block and an internal thread <NUM> formed in a recess in the lower side of the lid. The assembly can be finalized by mounting the clamping ring <NUM>.

Alternatively, the housing <NUM> can be integrated in the well cover frame, such as by being casted in one piece with the well cover frame. The arrangement may alternatively be pre-assembled, wherein the housing and all the elements installed in the housing are combined to one unit before attaching the assembly to the well cover frame.

For the purpose of mounting to the well cover frame, the arrangement may comprise a mounting plate <NUM> which is connected to the housing <NUM> and having properly located boltholes <NUM> for bolting the housing to the inner side <NUM> of the well cover frame.

For reasons of completeness it serves to mention that reference number <NUM> refers to a stop heel carried on the bolt <NUM>, the heel <NUM> preventing involuntary unscrewing of the bolt. Slide bearings <NUM>, such as made of self-lubricating alloy metal, may advantageously be inserted between elements of telescoping relative movement in the arrangement, such as between the housing <NUM> and the sleeve <NUM>, and/or between the sleeve <NUM> and the cylinder <NUM>. Reference number <NUM> indicates a suggested location for a drainage holes in the bottom of the housing.

It shall be understood that the lifting and lowering device of the invention can be implemented also in cement casted wells and well cover lids molded in cement. To this purpose, e.g., the mounting plate <NUM> can be developed into the form of a U-shaped suspension member which is molded into the cement material in an upper rim portion of a cement well or cement ring opening. In a corresponding way, the bolt hole <NUM>, <NUM>, <NUM> can be formed in a reinforcement plate which is molded into the cement material in a peripheral region of a well cover lid made of cement.

Claim 1:
An arrangement for a well cover, the arrangement comprising a lifting and lowering device which is arranged for lifting and unlocking or for lowering and locking, respectively, of a well cover lid in relation to a well opening, the arrangement comprising a housing (<NUM>) attached or mountable to an inner side (<NUM>) of a well opening, the housing (<NUM>) accommodating a stationary and non-rotationally anchored nut (<NUM>) having an internally threaded hole for a through-going, externally threaded bolt (<NUM>), a piston (<NUM>; <NUM>) supported rotationally on the bolt (<NUM>) and slidably received in the housing (<NUM>), wherein an upper end (<NUM>) of the piston (<NUM>; <NUM>) is arranged for supporting a well cover lid while simultaneously an upper end (<NUM>) of the bolt (<NUM>) projects above the upper end (<NUM>) of the piston (<NUM>; <NUM>) and being accessible for engagement with a turning tool via a hole (<NUM>; <NUM>; <NUM>) which opens in an upwards facing side of the well cover lid at a location inside of the periphery (<NUM>) of the well cover lid when the housing (<NUM>) is attached to an inner side (<NUM>) of a well opening, whereby the well cover lid will be forced by the piston (<NUM>; <NUM>) to follow the axial displacement of the bolt (<NUM>), upwards or downwards, as the bolt is turned under threaded engagement with the nut (<NUM>), characterized in that said hole (<NUM>; <NUM>; <NUM>) comprises an opening (<NUM>) of a first diameter mouthing in the upwards facing side of the well cover lid, said opening via a radial shoulder (<NUM>) continuing in a lead-through (<NUM>) of a second diameter which is smaller than the first diameter, wherein a non-threaded length in the upper end of the bolt (<NUM>) forms a neck (<NUM>), wherein in the area of the upper end of the neck portion (<NUM>), a clamping ring (<NUM>) is inserted under tension in a groove formed in the exterior of the bolt (<NUM>) and in mounted position abuts the radial shoulder (<NUM>) which connects the first and second diameters of the hole.