TECHNICAL FIELD

The present invention relates to a service pit to be installed on a foundation and comprising a module, which have a metal support frame, e.g. steel, and have at least two longitudinal side walls and a bottom, where at least the side walls exhibiting an inner wall and an outer wall arranged at a distance from each other, said side walls, bottom and foundation bounding a hollow space. The invention also relates to a method for assembling the service pit according to the invention, and further it relates to a method for installing the service pit on a foundation in a space in the ground.

BACKGROUND ART

Service pits of the above mentioned kind are known from e.g. DE4324339 and

DE4345415, and are used in e.g. workshops for installation or maintenance of motor vehicles, hence the staff in a comfortable upright position may work under the vehicle. During installation of such a pit the hollow space between the side walls and between the bottom and the foundation is normally filled with a settable material, such as concrete and/or an isolating foam. In order to have the necessary strength to resist the pressure stresses to which the pit is subjected to, the known pits are made of relatively thick steel plates and having a relatively large distance of about 200 mm between their side walls. Thus, the known pits suffer from the disadvantage that a large amount of steel and also fill material have to be used to obtain the required strength. Further, according to known prior art normally the outer wall of the pit extends all the way down to the foundation. Accordingly, the fill material will be filled into the hollow space bounded by the outer side walls, the inner side walls, the bottom and the foundation, implying difficulties in detecting desired filling in all parts of the hollow space, especially if the filling is performed in one step via an upper gap between said side walls, as described in the above cited prior art. Hence, there is a risk of air being trapped in the hollow space, especially in the bottom region, thus resulting in a weakened construction. In DE-G-9320679, which is a branch off from DE4324339, it is suggested to provide a longitudinally angled bottom section to minimize air trap risk, which however results in a complex structure leading to extra cost. Moreover, according to prior art methods it may be complicated to install supply channels, etc. (e.g. for ventilation, compressed air, electricity). DISCLOSURE OF THE INVENTION

It is an object of the present invention to solve, or at least to minimise the above mentioned problems and to provide a service pit which exhibits the necessary strength while the amount of steel and/or fill material to be used is reduced.

This is achieved by a service pit according to the claims. Hereby is achieved that at least the inner and outer walls may be made with a smaller thickness, hence reducing the amount of steel used. This is due to the rib plates make the service pit structure more rigid and thus stronger and easier to produce in a modularized manner, with minimized risk for trapped air. In addition, the thus reinforced service pit may be manufactured with less distance between the inner and the outer wall of the side walls, thereby reducing the required amount of fill material to be used.

In principle, the rib plates may have any suitable form that strengthen the pit construction, such as bars or tubes. However, it is preferred that the rib plates are made of plate material, preferably the same kind of metal plate as the inner and outer walls, e.g. 3 mm steel plate. The rib plates extend essentially perpendicular to the plane of the side walls and may be formed as smaller plate sections that are evenly distributed in the hollow space. It is, however, preferred that the rib plates extend over the whole hollow space and have the form of an U like the rib plates in a double-hulled vessel.

In order to ensure a good and precise attachment of the rib plates to the inner walls, the rib plates are preferably provided with engagement means for cooperation with corresponding means provided in the inner walls. In a preferred embodiment said engagement means on the rib plates comprise protruding fitting members adapted to exactly fit in to corresponding recesses in the inner walls. In order to obtain high accuracy and precision the fitting members and recesses are preferably produced by the use of laser cutting, as well as the contours of the rib plates . To make the construction stronger the lower corners of the side walls may be provided at a wide angle relative to vertical, preferably about 45°. Further, the service pit may be provided with a horizontal longitudinal beam arrangement in the hollow space of the lower corner region. This facilitates a strong construction and enables a reduced width inside of the bottom part, which enables arranging path way for lifting devices in the pit that is only 1300 mm. In many pits there is a need of using 1500 mm, which requires more costly equipment. According to another aspect of the invention the service pit is assembled by a method comprising the steps as defined in claim 12.

It is hereby obtained that the service pit structure is more rigid and thus stronger.

The inner walls may be attached to the rib plates in any suitable manner, however it is preferred that the inner walls are attached to the rib plates by bringing engagement means on the rib plates in engagement with corresponding means provided in the inner walls. In a preferred embodiment protruding fitting members on the rib plates are introduced into corresponding recesses in the inner walls.

According to yet another aspect of the invention the service pit is installed by a method comprising the steps as defined in claim 15. It is hereby obtained many advantages, e.g. that extra stability of the bottom region is provided, and that the space above the fill wall is kept freely available to enable arranging supply passages channels for ventilation etc. Further it is an advantage not to have to make any adjustment to the outer wall of the service pit in relation to the foundation, but instead use a separate fill wall that is easily accessible and handled. It also provides the advantages of enabling good control that the first filling step is performed in a desired and predetermined manner, by means of visibly checking that the level is optimal, i.e. when fill material everywhere reaches the upper edge of the fill wall. Furthermore is facilitates the use of a specific kind of fill material in the bottom region, which may be advantages in some applications.

The service pit according to the invention may be pre-produced or it may be assembled on site.

Further features and details of the service pit according to the invention will be apparent from the detailed description.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 is a perspective view of a service pit according to one embodiment of the invention,

Fig. 2 is a cross section view of the service pit shown in Fig. 1, Fig. 3 is a view of a rib according to a preferred embodiment of the invention, Fig. 4 is a perspective view of an inner wall , Fig. 5 is a perspective view of a beam arrangement, Fig. 6 is a perspective view of a floor plate,

Fig. 7 is a perspective view of an attachment member for attachment of a wheel track,

Fig. 8 is a view of an adjustable foot for adjusting the position of the service pit during installation,

Fig. 9 is a side view and a view from above of a wheel track,

Fig. 10 is a perspective view of a portion of the service pit in Fig. 1 provided with a wheel track,

Fig. 11 is a view of details for attachment of a wheel track to the service pit,

Fig. 12 is a side view of the attachment of the wheel track in Fig. 9 to the service pit by means of the attachment member in Fig. 7,

Fig. 13 is a view of an installation step of the service pit in Fig. 2, where a separate substantially vertical fill wall is attached to the foundation in the extension of both the outer walls,

Fig. 14 is a view of an installation step of the service pit in Fig. 2, where fill material is supplied to the lower region up to an upper edge of the fill walls, and,

Fig. 15 is a view of an installation step of the service pit in Fig. 2, where fill material is supplied in to the hollow space between the inner and outer walls to the top.

DETAILED DESCRIPTION

The invention will hereinafter be described in more detail with reference to the appended drawings. The following description should be considered as preferred form only, and is not decisive in a limiting sense. In Fig. 1 is shown a perspective view of a service pit 1 according to one embodiment of the invention. In the shown embodiment the service pit 1 comprises several modules 3, each having two longitudinal side walls 5, 6 and a bottom 7. Each module 3, has a longitudinal length M of about 1800 - 3200 mm, more preferred 2400 mm. The reason why it is preferred to use modular lengths as mentioned above, is that it is preferred to use modules that are multiples of the basic building module measurement 600 mm and that it from the perspective of other aspects with this kind of construction project is an advantage to use four times the basic modularity due to the fact that it will fit well into most existing production lines for producing the metal plates forming the inner 9 and outer 8 walls of the pit 1.

In Fig. 2 it is shown that each side wall 5, 6 comprise of an inner wall 8 and an outer wall 9 arranged at a distance from each other, thus bounding a space 10 them between. Fig. 2, shows a cross section of the service pit shown in Fig. 1, further comprises a number of rib plates 11 (see Fig 3) being arranged transversally in the space 10 and securely attached to at least the inner and outer walls 8, 9. In the shown preferred embodiment the rib plates 11 are made of the same kind of metal plate as the inner walls 8, preferably 2-6 mm steel plate (most preferred 2-4 mm) and extend

perpendicular to the plane of the side walls over the whole space 10, thus exhibiting the form of an U. Hereby the width (in the longitudinal direction of the service pit 1) of a rib plate 11 substantially equals to the material thickness of a rib plate 11. The distance between the rib plates is preferably the basic building module measurement, i.e. 600 mm. In some installations it is an advantage to supplement with support ribs (not shown) in parallel between each neighboring pair of the rib plates 11, to assist in keeping the desired distance between the inner and outer walls 9, 8 when fill material is supplied. Preferably the lower edge of such support ribs is positioned above the floor plate 72. As these rib plates 11 make the service pit structure more rigid and thus stronger, the applied amount of steel may be reduced, because the inner and the outer wall of the side walls 8, 9 may be made with a smaller thickness than conventionally used, e.g. steel plate of about 3 mm thickness. In addition, the thus reinforced service pit may be manufactured with less distance, preferably about 80 - 120 mm, between the inner 8 and the outer wall 9 of the side walls 5, 6 thereby reducing the required amount of fill material to be used. To provide for extra material for secure attachment of the outer rib 1 la, to abut the vertical edges of the walls 8,9, the outer rib 11a is somewhat larger than the other, intermediate rib plates 11.

At the top of the pit 1 there are arranged two parallel U-beams 51, which preferably span the whole length of the pit 1. Supporting distance members 50 extend transversally between the two beams 51, as also lifting members 52.

As shown, the lower outer corners 18 between the side walls 5, 6 and the lower edge of the rib plates 11 are provided at a first wide angle a relative to vertical, preferably about 110-135°, thus making the construction stronger. The upper edge 71 of the rib plates 11 (see fig 3) are also provided at a wide angle β relative to vertical, which may be less wide than the first angle a, to have the floor plates 70 inclined at an angle β relative to vertical, preferably about 95-105°, to allow liquid to collect in a preformed channel 74 in the floor plate 70, i.e. in the middle of the pit. The shown service pit 1 is also provided with a horizontal longitudinal beam arrangement 19 in the lower corner region 18, which further contributes to a strong construction and enables a reduced width PW inside of the bottom part. It enables arranging a path way for lifting devices of reduced span width in the pit, e.g. that is only 1300 mm. In many pits there is a need of using 1500 mm, which requires more costly equipment.

The service pit 1 is further shown to comprise a stairway 12, which is positioned at an end wall 15 of the service pit 1.

Fig. 3 shows one rib half 11 ' of an U-shaped rib plate 11 according to the preferred embodiment of the invention, e.g. to provide for more easy transportation. As schematically indicated in Fig. 3 each rib half 11 ' is provided with protruding fitting members 13, preferably at least two fitting members 13 along the inner edge 61. These fitting members 13 preferably protrude about the same distance as the thickness of the wall 8 to be fitted there. Further, the rib plates 11 are provided with holes 14, so that the amount of steel is reduced without appreciably compromising the strength of the construction. To facilitate the manufacturing of the U-shaped rib plates 11, these are preferably made of two identical rib halves 11 ', which may be welded together, thus making the rib plates symmetric, also facilitating use of the same plates for the walls 8, 9 at both sides 5, 6 of the pit. Further each rib half 11 ' is arranged with a recess 72 forming one half of the space for mounting of the preformed channel 74 in the floor plate 70. The width of the recess 72 is preferably many times smaller than the width W of a rib half 11 '. Preferred measures of a rib half 11 is a height H of about 1700 - 2000 mm, a width W of about 800 - 900 mm, i.e. wherein the width W is about 40-60 % of its height H. The portion of the rib half 11 spanning the major portion of the space between the walls 8, 9, which also is the most thin part of the rib half 11, has a transversal width T that is about 80 - 120 mm.

Further Fig. 3 indicates that at the outer periphery of the rib 11 there is arranged a flange, preferably by bending the edge of the plate, which flange 60 (e.g. 20-30 mm wide) is used for attachment of the outer plates 9 to the rib plates 11. Preferably this is achieved by using screws, more preferably self-threading kind, e.g. having premade holes in the flange 60 of about 5-6 mm and appropriate corresponding screws adapted to that hole size. Thanks to the use of screws an efficient manufacturing is achieved that also eliminates possible difficulties related to welding, e.g. facilitates the use of less corrosive metal plates (e.g. galvanized) that are more difficult to weld. In the preferred embodiment the inner plates 8 are made of conventional (black) steel plates that are relatively cheap and easy to weld, whereas on the outer walls 9 are made from galvanized plates.

In Fig. 4 is shown is a perspective view of an preferred embodiment of an inner wall plate 8', which is provided with recesses 16 adapted to exactly accommodate the protruding fitting members 13 on the rib plates 11, wherein preferably each inner wall plate 8' is arranged with a plurality of parallelly arranged rows of recesses 16, to enable fitting of a plurality of parallelly arranged rib plates 11. In order to obtain high accuracy and precision the fitting members 13 and recesses 16 are preferably produced by the use of laser cutting. The rib plates 11 may similarly be attached to the outer walls 9.

In Fig. 5 there is shown one piece of the beam arrangement 19 used in the corner area 18 of the service pit 1. The beam 19 preferably has a length 1 that is larger than the modular width M, i.e. a width that is larger than 2,4 m, preferably a width that can span at least two modules, e.g. between 5-10 m.

In Fig. 6 there is shown a floor plate 70, having a central channel 74. The length of the floor plate is preferably the same as the length M of a module, e.g. 2400 mm. As can be seen there is preferably arranged an L-bend 72 adjacent the longitudinal outer sides of the floor plate 70, which L-bends 72 are used to sealingly join the floor plate 70 with the lower edge of the inner side wall 8, preferably by the use of welding. As shown, e.g. see Fig. 2, the bottom of the channel 74 is arranged to create runoff for liquid, to lead collected liquid to a drainage (not shown). As a consequence the depth of the channel 74 varies in the longitudinal direction, which in turn results in the need of floor plates having a proportionally varied original/nominal width. Hence, the nominal width before bending it varies giving it a triangular form, which is being bent to the desired form having the edges 72 in parallel and a channel 74 with varying depth.

In the following some preferred production steps will be presented regarding the production of the pre- fabricated pit structure according to the invention. Firstly the upper U-shaped supporting beams 51 will be positioned on to the floor and are accurately positioned in relation to each other by means of transversal support and distance members 50 (see Fig. 1). Some of the distance elements 52 are specifically designed to be used for lifting and moving of the pit 1.

Thereafter a jig (not shown) is positioned on to the support beams 51. In the next step the inner walls 8 will be correctly positioned by means of the jig (n.b., the pit 1 will be upside down during the prefabrication thereof). Now the beam arrangement 19 is welded on to the inner plates 8 and thereafter also the floor plates 70. In the next step the rib plates 11 will be attached to the pit 1, by means of lifting each rib half 11 in to position by the use of the inter fit between the fitting member 13 and recesses 16. Now the rib halves 11 are welded, preferably by means of intermittent welding, into connection with the inner walls 9, the floor plate 70 and also to each other at the joining centrally positioned vertical edges. In the next step the outer plates 8 are fit on to the outer edges, i.e. the flange 60, of the rib plates 11, e.g. by means of screws.

Fig. 8 shows an adjustable foot 20 for adjusting the position of the service pit 1 during installation. The shown adjustable foot 20 comprises a bottom plate 21 with holes 22 for securing the foot 20 to a foundation 40, a substantially vertical threaded rod 23 bearing a movable supporting element 24, comprising holes 25 for attachment to the outer wall 9. The supporting element 24 is vertically movable by means of a nut arrangement 26, interacting with the threaded rod 23

Fig. 7 shows a perspective view of a horizontally extending support and attachment member 30 for attachment of a wheel track 32, not shown in this figure. The wheel track attachment member 30 is also shown in Fig. 2 and Figs. 10 to 12, and it comprises a number of screw holes 31. The wheel track 32 is an optional, auxiliary equipment.

In Fig. 9 is seen a side view and a top view of a wheel track 32 having a mounting member 34 for attachment thereof to the attachment member 30. On the other side there is an anchoring member 35 for anchoring of the wheel track in the floor of the service place. The wheel track comprises a water tray 33 to collect waste water from the tires of a vehicle. Fig. 10 shows a perspective view of a portion of the service pit 1 shown in Fig. 1 provided with a wheel track 32, and Fig. 11 and 12 show in more detail the attachment of a wheel track 32 to the support and attachment member 30, where screws, (not shown), may be used to attach the housing member 34 by means of the holes 31, 39. In Figs. 13 to 15 are shown three consecutive steps of an installation of the service pit 1. Thus, first the service pit 1 has been positioned in a cavity in the ground, not shown, to stand on a foundation 40 and adjusted into its intended position by means of the adjustable feet 20. To have the pit 1 situated a predetermined distance above the foundation 40.

A separate substantially vertical fill wall 41 is, as shown in Fig. 13, attached to the foundation 40 adjacent the extension of both the outer walls 9. This fill wall 41 has a limited height, about 300-500 mm. Sufficiently high to reach above the level of the floor 70, but not higher than needed to fill the bottom region 43 and the corner area 18 of the pit 1. Then soil is refilled into the cavity outside of the fill wall 41 and up to its upper edge.

Thereafter, as shown in Fig. 14, fill material 42, such as concrete, is supplied to the lower region 43 up to the upper edge 44 of the fill walls 41. This will provide the possibility for inspecting that filled material 42 has actually been supplied to all desired parts of the bottom region of the pit, since it will be easily detected visually that the fill material reaches the upper edge, at least adjacent the upper edge of the fill wall 41.

In Fig. 15 the final filling step is shown, where fill material 42 is supplied in to the hollow space 10 between the inner and outer walls 8, 9 to the top. This step will be performed after the fill material 42 in the lower region 43 has solidified, or at least to a certain extent.

There are several advantages thanks to this. Firstly it provides for extra stability of the bottom region, and secondly it keeps the space above the fill wall 41 freely available to enable arranging supply passages channels for ventilation etc. Further it is an advantage not to have to make any adjustment to the outer wall 14 of the pit in regard to the base plate 60, but instead use a separate fill wall 41 that is easily accessible and handled. It also provides the advantages of enabling good control that the first fill stage is performed in a desired and predetermined manner, by means of visibly checking that the level is optimal, i.e. when fill material everywhere reaches the upper edge of the fill wall 41. Furthermore is facilitates the use of a specific kind of fill material in the bottom region, which may be advantages in some applications.

Many other variations are also possible, as will be readily understood by the person skilled in the art. Further it is evident that the advantages of using a separate fill wall , as defined in claim 15, may also be used in connection with other pit designs, e.g. pit modules using a more traditional design including beams in place of rib plates , and therefore it is foreseen that separate protection may be applied for regarding this aspect in a divisional application.