JP7471673B2 - Pipe connection block for underground boxes - Google Patents

Description

This invention relates to a pipe connection block for underground boxes that forms a part for connecting pipes of underground boxes such as manholes and handholes.

An example of a pipe connection block for an underground box is disclosed in Patent Document 1 below.

This underground box pipe connection block is a rectangular or cubic block with multiple pipe insertion holes formed in the thickness direction, and has a convex guide on the top surface and one side of the block in the direction perpendicular to the thickness direction. Meanwhile, a concave guide rail is formed on the bottom surface and the other side in the direction perpendicular to the thickness direction, with a size that allows the convex guide to fit and slide.

Many types of pipe connection blocks for underground boxes are available, all of which are the same size but have different sizes and numbers of pipe insertion holes. When in use, multiple pipe connection blocks for underground boxes are stacked together by fitting the convex guides and concave guide rails together, and then fitted into an opening in the wall of the underground box. The assembled blocks are fixed in place with mortar, epoxy resin, etc., filled between the blocks and the opening.

In addition, to achieve watertightness between the stacked blocks, the notches formed around the entire periphery of the block's outer surface are filled with a water-swelling watertight material.

In addition to the blocks disclosed in Patent Document 1, there are resin concrete blocks that do not have convex guides and concave guide rails, but are built up using a caulking agent. In other words, many different types of these blocks with different sizes and numbers of pipe insertion holes are prepared in advance, and are assembled and shipped according to orders.

Such blocks have the advantage of being able to meet a variety of requirements, unlike the block in Patent Document 1, which is joined by a convex guide and a concave guide rail.

Japanese Patent No. 3505399

However, many different types of blocks must be prepared, placing a heavy burden on inventory management. Moreover, the integration of the blocks using caulking agents usually requires about a day of curing, which takes time and makes it impossible to handle emergency orders. Not only that, but curing requires space, just like inventory management. In addition, the blocks are made of resin concrete, which means they are heavy and have a high specific gravity, making them difficult to handle and work with.

Therefore, the main objective of this invention is to be able to meet a variety of requirements and to enable easy assembly without the need for caulking.

The means for achieving this is a pipe connection block for an underground box, which includes a housing part having a square tube shape with both front and rear surfaces facing in the thickness direction of the wall of the underground box, and a pipe connection hole extending in the thickness direction of the wall within the housing part and into which an end of a pipe is inserted and held, the housing part and the main body member having the pipe connection hole are formed of synthetic resin, and there is one pipe connection hole. A fitting structure is formed in each of a pair of side surfaces of the housing part that are parallel to each other and a pair of side surfaces that are perpendicular to the pair of side surfaces, such that the pair of side surfaces can fit together, and at least one of these fitting structures has a slip-out prevention engagement part that allows the opposing side surfaces of the other underground box pipe connection block to be joined to be inserted by sliding them, while preventing the side surfaces from moving away from each other. In addition, a connecting means is provided to connect the other of the two side pairs having the fitting structure to the opposing side of the other underground box pipe connection block to be joined, and a water-expandable sheet that expands by absorbing moisture is provided on all sides of the housing section.

In this configuration, an assembly is obtained by assembling the necessary number of pipe connection blocks for underground boxes, each having a pipe connection hole of the required size, in the same arrangement as the number of pipes to be connected. During assembly, the sides of the housing are joined together using an interlocking structure. One of the two pairs of side surfaces having an interlocking structure is joined by sliding and engaging with a non-slip engagement portion. The other side surfaces having an interlocking structure are joined together using a separate or integrated connecting means. A water-swellable sheet expands between the joined sides to seal off water. Because the main body member is made of synthetic resin, the pipe connection block for underground boxes is lightweight.

According to this invention, a structure with one pipe connection hole, i.e., a single-strand type, is assembled, and there is no need to manufacture structures with multiple pipe connection holes. A variety of multi-strand assemblies can be obtained according to demand with fewer types of pipe connection blocks for underground boxes. This reduces the burden of inventory management.

Moreover, the two pairs of side surfaces have an interlocking structure, and one pair of side surfaces is formed with a non-slip engagement portion, so joining one pair of side surfaces is easy, and joining the other pair of side surfaces is also easier than joining with a caulking agent, since it is done by a connecting means. Furthermore, since the main body member is made of synthetic resin and has a small specific gravity, the underground box pipe connection block is lightweight, improving handling and workability.

In addition, all sides of the housing are equipped with water-swelling sheets, so when they are joined together and buried underground, water-tightness is automatically achieved between the underground box pipe connection blocks. This reduces the burden in terms of time and workability compared to joining with caulking agent or filling with a separate water-swelling water-stopping material, and, combined with reduced inventory management, simplifies the entire process.

FIG. FIG. 2 is a perspective view of a pipe connection block for an underground box and a pipe. FIG. FIG. 2 is an exploded perspective view of a pipe connection block for an underground box. FIG. FIG. 2 is a front view of a pipe connection block for an underground box. 7 is a cross-sectional view taken along line AA in FIG. 6. FIG. 7 is a cross-sectional end view of the B-B section of FIG. 6. FIG. FIG. 13A and 13B are perspective views of different sized pipe connection blocks for underground boxes. 12 is a six-view diagram and a cross-sectional diagram of the pipe connection block for the underground box of FIG. 11 . FIG. 13 is a perspective view showing an example of joining pipe connection blocks for an underground box. FIG. 13 is a plan view of a joined inground box pipe connection block. FIG. 13 is a perspective view showing an example of joining pipe connection blocks for an underground box in the vertical direction. A side view of a pipe connection block for an underground box joined in the vertical direction, viewed from the right side. FIG. 4 is a cross-sectional view showing a connected state by a connecting pin member. FIG. 4 is a cross-sectional view showing the function of the water-swellable sheet. 13 is a perspective view showing an example of joining pipe connection blocks for underground boxes of different sizes. FIG. FIG. 20 is a side view showing the joint portion of FIG. 19 . FIG. 20 is a plan view showing the joint portion of FIG. 19 . FIG. 20 is a side view showing the joint portion of FIG. 19 .

One embodiment of the invention is described below with reference to the drawings.

Figure 1 shows a partially cutaway perspective view of an underground box 12 equipped with an underground box pipe connection block 11 (hereinafter referred to as a "connection block"). As shown in this figure, the underground box 12 has an assembly 11a formed by assembling multiple connection blocks 11 fixed inside an opening 22 formed through a wall portion 21.

The assembly 11a is made by joining multiple connection blocks 11 together, and is assembled in advance, then transported to the site and fixed to the underground box 12. Fixing is performed by filling the space between the assembly 11a and the opening 22 with epoxy putty 13. In addition to epoxy putty 13, caulking agents, mortar, and other fillers can also be used.

First, to give an overview, the connection block 11 is formed in a rectangular tube shape as shown in Figure 2, and has a housing part 32 that forms the rectangular tube-shaped outer surface of the main body member 31, and a tube connection hole 33 formed within the housing part 32.

The housing unit 32 is fixed with both the front and rear ends facing in the thickness direction of the wall 21 of the underground box 12, and is formed to fit within the wall 21. In the illustrated example, the length L (see FIG. 2) of the housing unit 32 in the front-to-rear direction is the same as the thickness t (see FIG. 1) of the wall 21. Therefore, the front surface 32a of the housing unit 32 is fixed flush with the outer surface 21a of the wall 21, and the rear surface 32b is fixed flush with the inner surface 21b. Note that the length L of the housing unit 32 in the front-to-rear direction and the thickness t of the wall 21 may not be the same.

The housing 32 in the illustrated example is square when viewed from the front, and has four sides 34, 35, 36, and 37 around it, as shown in FIG. 2.

The tube connection hole 33 extends in the thickness direction of the wall 21 and is the portion into which the end 14a of the tube 14 is inserted and held, penetrating the housing 32. In addition, a retaining ring 71 is provided inside to prevent the end 14a of the inserted tube 14 from falling out.

Here, we will briefly explain the tube 14. The tube 14 is intended to protect electric wires and cables of electrical equipment, and as shown in Figure 2, the cross section in the direction perpendicular to the longitudinal direction has a structure in which rectangular peaks 41 and circular valleys 42 are alternately repeated. The end 14a of the tube 14 is a cylindrical insertion portion. At the tip of the end 14a, as shown in the cross-sectional view of Figure 3, a circular return portion 43 is formed to prevent it from coming loose, and a gasket 44 for stopping water is provided at a position set back from this. The size of the rectangular peaks 41 corresponds to the size of the housing portion 32.

The connection block 11 will now be described in detail. As shown in FIG. 4, the connection block 11 is composed of a main body member 31 having a housing portion 32 and a tube connection hole 33, a retaining ring 71 held in the tube connection hole 33, and a water-swelling sheet 81 attached to the outer periphery of the housing portion 32. The main body member 31 and the retaining ring 71 are all made of synthetic resin. For example, high-density polyethylene is preferably used as the synthetic resin that constitutes the main body member 31. When high strength is required, for example, glass fiber reinforced polypropylene may be used.

The main body member 31 has one tube connection hole 33 that is circular when viewed from the front, in the center of both the front and back sides. In other words, it is a single-strand type.

Note that the main body member 31 in FIG. 4 shows its front surface 32a, upper side surface 32g, and left side surface 32f.

First, we will explain the tube connection hole 33.

The front side portion 33a of the tube connection hole 33, which extends from the front side 32a to the rear side 32b, is sized to receive the end portion 14a of the tube 14, and the rear side portion 33b, which is located further rearward, is formed with a smaller diameter than the front side portion 33a. The boundary between the front side portion 33a and the rear side portion 33b is a step portion 33c that receives the retaining ring 71.

The tube connection hole 33 is circular when viewed from the front, while the housing portion 32 is square when viewed from the front, so that recessed spaces 39 are formed in the four corners on both the front and rear sides, leaving behind the cylindrical portion 38 that forms the tube connection hole 33. The rear portion 33b of the tube connection hole 33 has a smaller diameter than the front portion 33a, so as shown in Figure 5, which is an oblique view of the rear surface 32b of the main body member 31, the multiple recessed spaces 39 on the rear surface 32b are formed via ribs 38a that support the cylindrical portion 38. The formation of the recessed spaces 39 contributes to reducing the weight of the main body member 31.

Note that FIG. 5 shows the rear surface 32b, lower side surface 32h, and left side surface 32f of the main body member 31.

In the tube connection hole 33, at two positions on one diagonal line in front of the stepped portion 33c, a retaining hole 47 is formed that penetrates the cylindrical portion 38 in the radial direction as shown in Figures 4 and 6. The retaining hole 47 is for holding the retaining ring 71 in a non-rotatable state so that it does not fall off.

A stopper 48 is formed on the inner circumferential surface of the tube connection hole 33 at a position closer to the front side than the retaining hole 47 and corresponding to the front surface of the retaining ring 71, as shown in Figures 2, 6, and 7, to prevent the retaining ring 71 from falling off and to improve the pull-out strength as necessary. This stopper 48 protrudes radially inward and has a receiving surface 48a that receives the front surface of the retaining ring 71. It is recommended that the stopper 48 be formed when the diameter of the tube connection hole 33 is large.

As shown in Figures 4 and 6, the retaining ring 71 has a circular shape in front view with a cutout 72, and protrusions 73 are formed at two diametrically outer circumferential surfaces. The protrusions 73 are fitted into the retaining holes 47 of the tube connection holes 33 in the main body member 31, and the protrusions 73 are fitted into the retaining holes 47 by reducing the diameter of the ring so as to narrow the cutouts 72. On the inner circumferential surface of the retaining ring 71, multiple claws 74 are provided at intervals that allow elastic deformation, extending from the front surface diagonally rearward in the inner diameter direction.

Next, we will explain the housing part 32 of the main body member 31.

As mentioned above, the housing 32 has four side surfaces 34, 35, 36, and 37. That is, one pair of side surfaces are parallel to each other and form a pair, and the other pair of side surfaces are perpendicular to the first pair of side surfaces. One pair of side surfaces forms the right side surface 32e or the left side surface 32f that extends vertically, and the other pair of side surfaces forms the upper side surface 32g or the lower side surface 32h that extends horizontally. In this description, one pair of side surfaces is taken to constitute the right side surface 32e or the left side surface 32f, and the other pair of side surfaces is taken to constitute the upper side surface 32c or the lower side surface 32d.

The first and second side pairs are formed with mating structures 51, 52 that allow the paired side surfaces to fit together. The mating structures 51, 52 extend parallel to the front surface 32a or rear surface 32b at a constant width in the middle of the side surfaces in the front-to-rear direction, and the mating structure 51 formed on the first pair of side surfaces has a wider mating width w than the mating structure 52 formed on the other pair of side surfaces (see Figures 7 and 8). The mating structures 51, 52 are formed of convex portions 51a, 52a and concave portions 51b, 52b.

At least one of the two sets of fitting structures 51, 52, the fitting structure 51 with the wider fitting width w formed on one pair of side surfaces in this example, has a slip-out prevention engagement portion 53. That is, the slip-out prevention engagement portion 53 allows the opposing side surfaces of the other connection block 11 to be joined to be slid for insertion, while preventing the sides from moving away from each other. As shown in FIG. 8, the slip-out prevention engagement portion 53 is composed of a guide piece 53a formed on the protrusion 51a and a groove portion 53b formed on the recess 51b. The guide piece 53a is formed on both sides of the protrusion 51a in the fitting width direction over the entire length. The groove portion 53b is formed deep inside the recess 51b.

These fitting structures 51, 52 are formed in the middle of the side in the front-to-rear direction. Specifically, the fitting structure 51, which has a wider fitting width w, has the midpoint of the fitting width w set slightly forward of the midpoint of the side in the front-to-rear direction, as shown in FIG. 8. The other fitting structure 52 has the midpoint of the fitting width w set slightly rearward of the midpoint of the side in the front-to-rear direction, as shown in FIG. 7.

A groove 54 is formed on each side of the housing 10 at a constant width and extending parallel to the front surface 32a and rear surface 32b. The groove 54 is used to secure the water-swellable sheet 81.

The water-swellable sheet 81 expands when it absorbs moisture, and can be obtained, for example, by incorporating a water-swelling material that expands by absorbing moisture into the nonwoven fabric. As the water-swelling material, powder, sheet, liquid, etc. can be used as appropriate, but using a fibrous material is preferable because it enhances the integration with the fibers that make up the nonwoven fabric. The water-swellable sheet 81 may be made of something other than a water-swellable nonwoven fabric.

The water-swellable sheet 81 is formed in a strip shape that corresponds to the width of the groove 54, and is fixed to the groove 54 using an adhesive or double-sided adhesive tape.

The connection block 11 is also provided with coupling means 55, 56 (see Figures 9 and 10) that join the other of the two side pairs having the interlocking structure 52 to the opposing side of the other connection block 11 to be joined. In other words, the coupling means 55, 56 hold the upper side 32g and lower side 32h of the connection block 11 in a superimposed state.

The connecting means 55, 56 are of two types: an internal connecting means 55 that connects opposing sides together, and an external connecting means 56 that connects adjacent sides together. The internal connecting means 55 is provided on the inside, that is, between the sides that are to be joined together, and the external connecting means 56 is provided on the surface that appears on the outside.

Specifically, the internal connection means 55 is composed of a connection pin member 55a as shown in FIG. 9 and a fitting hole 55b into which the connection pin member 55a is fitted as shown in FIG. 2 and FIG. 4.

The connecting pin member 55a has protrusions 62 extending in opposite directions at the center of both the front and back sides of the square plate portion 61. The protrusions 62 have a locking claw 62a at their tips, and a split groove 62b is formed in the middle of the axial direction.

The fitting holes 55b are formed on the side surfaces, i.e., four on each of the upper side surface 32g and the lower side surface 32h as shown in Figures 4 and 5. The fitting holes 55b are formed near the four corners of the side surfaces. The fitting holes 55b on the front surface 32a side are formed closer to the middle in the front-to-rear direction than the fitting holes 55b on the rear surface 32b side. The fitting holes 55b on the front surface 32a side have a square recess 57 around them into which the plate portion 61 of the connecting pin member 55a fits.

The exterior-type connecting means 56 is a plate-like connecting plate 63 that extends across adjacent side surfaces, and there are two types, an I-shaped connecting plate 63 (FIG. 10(a)) and an L-shaped connecting plate 63 (FIG. 10(b)), as shown in FIG. 10. The I-shaped connecting plate 63 connects flush side surfaces, i.e., the right side surfaces 32e and 32f, and the L-shaped connecting plate 63 connects the upper side surface 32g or the lower side surface 32h to the right side surface 32e or the left side surface 32f. Through holes 64 are formed on both sides of the connecting plate 63. These through holes 64 are portions into which screw members 65 are inserted as fasteners.

In order to properly secure the connecting plate 63, a fixing groove 58 of a certain width is formed in a desired shape as necessary along the front surface 32a and rear surface 32b of the upper side surface 32g and the lower side surface 32h, so that the connecting plate 63 can be fitted into the fixing groove 58. The width of the fixing groove 58 is the same or approximately the same as the width of the corresponding portion of the recess 57.

The fixing groove 58 in the illustrated example is formed over the entire longitudinal direction of the upper side surface 32g and the lower side surface 32h, and at both longitudinal ends, it has an extension portion 58a whose length corresponds to the portion of the connecting plate 63 to be fixed, extending to the right side surface 32e and the left side surface 32f.

Of the aforementioned fitting holes 55b, the rear fitting hole 55b is formed overlapping the fixing groove 58.

The connection block 11 with this configuration is formed according to the thickness of the pipe 14 to be connected. Therefore, the size of the main body member 31 will differ depending on the thickness of the pipe 14, but the length L in the front-to-rear direction of the main body member 31 will be the same even for connection blocks 11 of different sizes.

In addition, even for connection blocks 11 of different sizes, the positions at which the interlocking structures 51, 52 are formed and the size of the interlocking width w are the same. The width and position at which the fixing groove 58 is formed are also the same, but the form of the fixing groove 58 and whether it is necessary or not are determined appropriately.

That is, the engagement width w of the engagement structures 51, 52 is the same for all connection blocks 11 regardless of size, and their formation positions, i.e., the distance from the front surface 32a and the distance from the rear surface 32b, are also the same (see Figures 7 and 8).

Figure 11 is a perspective view of a connection block 11 in which the diameter of the connected pipe 14 is smaller than that of the connection block 11 shown in Figure 2, and Figure 12 shows its six faces and the C-C cross section.

Thus, the length L in the front-to-rear direction and the mating width w and formation position of the mating structures 51, 52 are the same for both, so although the connection blocks 11 in Figures 12 and 2 have different appearances due to differences in the size of the side surfaces, etc., they can be joined to each other on all sides 34, 35, 36, and 37.

The connection block 11 configured as above is used as follows:

The required number of connection blocks 11 are joined together in the desired arrangement according to the size of the pipes 14 to be connected to form one assembly 11a.

First, an example of joining two connection blocks 11 of the same size to each other at one pair of side surfaces, i.e., the right side surface 32e and the left side surface 32f, will be described. As shown in Figure 13, the convex portion 51a on the right side surface 32e of one connection block 11 is slid up and down in the longitudinal direction of the fitting structure 51 to engage with the concave portion 51b on the left side surface 32f of the other connection block 11. Then, as shown in Figure 14, the fitting structure 51 fits together and the anti-slip engagement portion 53 engages, and the two connection blocks 11 become one unit. The required number of connection blocks 11 are joined in the direction of one pair of side surfaces. No joining means is required for joining in this direction.

When connecting blocks 11 of the same size are to be joined to each other at the other pair of sides, i.e., the upper side 32g and the lower side 32h, an internal connection means 55 is used as shown in Figure 15.

That is, a connecting pin member 55a is interposed between the upper side surface 32g and the lower side surface 32h of the connecting block 11 to be superimposed. For example, one projection 62 of the connecting pin member 55a is fitted into the fitting hole 55b of the upper side surface 32g of the connecting block 11 located on the lower side, and the plate portion 61 is fitted into the recess 57 or the fixing groove 58 to prevent rotation. In this state, the other projection 62 of the connecting pin member 55a is fitted into the fitting hole 55b of the lower side surface 32h of the connecting block 11 located on the upper side. The number of connecting pin members 55a used does not necessarily have to correspond to the number of fitting holes 55b as shown in FIG. 15, and can be omitted as appropriate.

Figure 16 is a view from the right side surface 32e of the connection block 11 joined in the vertical direction, and the fitting structure 52 fits together to prevent misalignment in the front-to-rear direction. Also, as shown in Figure 17, between the opposing joined surfaces (upper side surface 32g and lower side surface 32h), a connecting pin member 55a connects the upper side surface 32g and the lower side surface 32h, and works in cooperation with the fitting structure 52 to achieve a high degree of unity.

Instead of the internal connection means 55, the external connection means 56 can be used for connection, but the internal connection means 55 not only connects the sides together but also connects internally, resulting in a good connection state with high integrity.

The assembly 11a obtained in this way is fitted and fixed in the opening 22 of the underground box 12 via epoxy putty 13, as shown in the cross-sectional view of Figure 18. After fixing, the water-expandable sheets 81 provided on all sides of the connection blocks 11 that make up the assembly 11a absorb moisture that seeps in from the soil and expand as shown by the white arrows in Figure 18. This provides a waterproof seal between the connection blocks 11 and between the epoxy putty 13.

When joining connection blocks 11 of different sizes in constructing the assembly 11a, internal connection means 55 can be used in part, but external connection means 56 is used, for example, as shown in Figure 19.

That is, an I-shaped connecting plate 63 is used where the right side surface 32e or the left side surface 32f are flush with each other, and an L-shaped connecting plate 63 is used where the upper side surface 32g or the lower side surface 32h is connected to the right side surface 32e or the left side surface 32f at a right angle. The connecting plate 63 is fitted into the fixing groove 58 including the extension portion 58a, and is fixed by inserting the screw member 65, which cuts into the main body member 31, through the through hole 64.

Figure 20 is a side view seen from the right side 32e when fixed using an L-shaped connecting plate 63, and Figure 21 is a plan view of it seen from the upper side 32g. Also, Figure 22 is a side view seen from the left side 32f when fixed using an I-shaped connecting plate 63. As shown in Figure 21, in the area where the through hole 64 of the connecting plate 63 and the fitting hole 55b of the main body member 31 overlap, it is recommended to use a bolt 65a instead of the drill-type screw member 65 described above, and insert a nut 66 on the back side to tighten it.

As shown in these figures, the connecting plate 63 cooperates with the fitting structures 51 and 52 to provide a strong fixation without misalignment.

As described above, the connection block 11 has a structure with one tube connection hole 33, and is used in a desired combination. Therefore, there is no need to prepare various types of blocks with multiple tube connection holes, and only different sizes of connection blocks 11 are required, which reduces the burden of inventory management.

In addition, one of the two sets of fitting structures 51, 52, the fitting structure 51, is formed with a retaining engagement portion 53, so the joining work is extremely simple. The joining of the side having the other fitting structure 52 is performed using connecting means 55, 56, which is much easier than joining using a caulking agent.

In addition, because the connection block 11 is made of synthetic resin, it has a low specific gravity and is lightweight. This makes it easy to handle during product management and transportation, and also makes it easy to attach to the underground box 12, significantly reducing the burden of the work.

In addition, because all sides 34, 35, 36, and 37 are equipped with water-swelling sheets 81, the connection block 11 can be simply joined and buried in the ground to automatically achieve water-stopping in the required areas. This makes it possible to reduce work time and space, unlike joining with caulking or filling with a separate water-swelling water-stopping material, and simplifies the entire process, along with reducing inventory management.

In addition, because necessary parts such as the fitting structures 51 and 52 are standardized for connection blocks 11 of different sizes, it is possible to reliably form a variety of assemblies 11a.

In addition to the anti-slip engagement portion 53, the connecting blocks 11 are provided with an internal connecting means 55 and an external connecting means 56 as connecting means, so that these can be freely used as needed to obtain the desired assembly 11a with high integrity.

The internal connection means 55 is constructed using a separate connecting pin member 55a, so it can be used only where necessary, and unlike cases where a pin-shaped protrusion is formed in advance, the desired assembly 11a can be flexibly configured.

The above configuration is one embodiment of the present invention, and the present invention is not limited to the above configuration, and other configurations may be adopted.

For example, the connection means provided may be either internal or external.

The other fitting structure 52 may also have a retaining engagement portion 53. In this case, only the exterior-type connecting means 56 is provided.

The retaining ring 71 may be made of a material other than synthetic resin.

DESCRIPTION OF SYMBOLS 11... Pipe connection block for underground box 12... Underground box 14... Pipe 14a... End 21... Wall 31... Main body member 32... Housing 32a... Front 32b... Rear 32e... Right side 32f... Left side 32g... Upper side 32h... Lower side 33... Pipe connection hole 51, 52... Fitting structure 53... Anti-pullout engagement portion 55... Internal type connecting means 55a... Connecting pin member 55b... Fitting hole 56... External type connecting means 62... Protrusion 63... Connecting plate 81... Water-expandable sheet

Claims (5)

A pipe connection block for an underground box, comprising: a housing part having a square cylindrical shape, both front and rear surfaces of which are fixed inside a wall of an underground box toward the thickness direction of the wall of the underground box; and a pipe connection hole extending in the thickness direction of the wall of the housing part and into which an end of a pipe is inserted and held,
The housing and the main body member having the pipe connection hole are made of synthetic resin,
The pipe connection hole is provided.
A fitting structure is formed on one pair of side surfaces of the housing that are parallel to each other and on another pair of side surfaces that are perpendicular to the one pair of side surfaces, such that the pair of side surfaces can be fitted together, and
At least one of the two sets of fitting structures is provided with a retaining engagement portion that allows the opposing side surfaces of the other underground box pipe connection block to be slid together and inserted, while preventing the side surfaces from moving away from each other;
A connecting means is provided for connecting the other of the two side pairs having the fitting structure to the opposing side of the other underground box pipe connection block to be connected;
A pipe connection block for an underground box, in which a water-expandable sheet that absorbs moisture and expands is provided on all sides of the casing. 2. The pipe connection block for an underground box according to claim 1, wherein the position at which the fitting structure is formed and the size of the fitting width are common to the pipe connection blocks for an underground box of different sizes. A pipe connection block for an underground box as described in claim 1 or claim 2, wherein the connecting means is at least one of an internal connecting means for joining opposing sides and an external connecting means for joining adjacent sides. 4. The pipe connection block for an underground box according to claim 3, wherein said internal connecting means is a connecting pin member having a projection that fits on opposing side surfaces and a fitting hole into which said projection fits. 4. The in-ground box pipe connection block of claim 3, wherein said exterior connecting means is a connecting plate extending across adjacent side surfaces.

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