JP7531381B2 - Manhole cover frame structure - Google Patents

Description

The present invention relates to a manhole cover frame structure that includes a manhole cover having an edge that hangs down from its periphery and a manhole frame having a fitting groove into which the edge of the manhole cover fits.

Normally, manhole covers and manhole frames can have dimensional variations due to manufacturing errors during molding, or thermal expansion or contraction due to environmental conditions after installation. Therefore, even if there are such dimensional variations, they are designed so that when the manhole cover is fitted into the manhole frame, there is a small gap between the edge of the manhole cover and the fitting groove of the manhole frame so that the manhole cover can close properly.

Manhole covers that are required to withstand a large load are relatively heavy, and even if there is a small gap between them and the manhole frame, they rarely wobble sideways. However, for applications that do not require such a large load, relatively lightweight manhole covers are used, and because they are light, they tend to wobble easily.

In particular, immediately after the manhole cover is attached to the manhole frame, surrounding gravel and other debris has not entered the gaps, and there is little friction between the contact surface between the manhole cover and the manhole frame, so there is no contamination by gravel or other foreign matter, and no scratches on the contact surface. If vibration or other forces are applied, the manhole cover is likely to rattle sideways, and the manhole cover may also rotate in a circumferential direction due to external forces such as the momentum of the worker placing his foot on it.

One conventional method for preventing a manhole cover from rattling or rotating is to attach a rubber sheet G or the like to the contact surface of the manhole cover with the manhole frame, as shown in Figure 7.

Although conventional methods for preventing rattling of manhole covers are widely known, no relevant literature is available, and therefore no prior art literature is disclosed.

The method for preventing manhole covers from rattling described above requires that the rubber sheet be attached to the manhole cover by hand, which is a time-consuming installation process and also raises the risk that the sheet may come off during transportation or installation.

The object of the present invention is to provide a manhole cover frame structure that can reliably suppress rattling and rotation of the manhole cover relative to the manhole frame in a simpler manner.

The manhole cover frame structure according to the present invention is characterized in that it is a manhole cover frame structure comprising a manhole cover having an edge portion hanging down from a periphery thereof and a manhole frame having a fitting groove into which the edge portion of the manhole cover is fitted,
When the manhole cover is fitted into the manhole frame, a preventing member that prevents the manhole cover from moving laterally relative to the manhole frame by being crushed is provided on at least one of an edge of the manhole cover and a fitting groove of the manhole frame ,
The prevention member is provided integrally when forming the manhole cover or the manhole frame .

According to this configuration, the prevention member is crushed , so that the edge of the manhole cover and the fitting groove of the manhole frame are tightly attached to each other, and as a result, rattling and rotation due to lateral movement of the manhole cover relative to the manhole frame are prevented. Therefore, there is no need to perform separate installation work, and rattling and rotation of the manhole cover relative to the manhole frame can be reliably suppressed in a simpler manner.
Furthermore, according to this configuration, since the prevention member is integrally formed with the manhole cover or the manhole frame, there is no risk of the prevention member coming off during transportation or installation, which improves ease of installation and reliably prevents the manhole cover from rattling or rotating relative to the manhole frame .

In the manhole cover frame structure according to the present invention, it is preferable that the shape of the prevention member is selected from the group consisting of a radially extending vertical rib shape, a circumferentially extending vertical rib shape, and a cylindrical shape.

With this configuration, the shape of the prevention member is more susceptible to crushing and/or deformation, so that the contact area between the manhole cover or manhole frame and the prevention member is easily crushed and/or deformed due to manufacturing errors or thermal expansion or contraction, etc., resulting in tight contact. As a result, rattling and rotation of the manhole cover relative to the manhole frame can be more reliably suppressed.

In the manhole cover frame structure according to the present invention, it is preferable that the shape of the prevention member is a vertical rib extending in the radial direction, and that the prevention member is provided in a fitting groove of the manhole frame.

With this configuration, the prevention member is provided in the fitting groove of the manhole frame, so it can be applied to various manhole covers that meet the standards of the manhole frame, and is easy to install.

In the manhole cover frame structure according to the present invention, it is preferable that the length of the prevention member in the radial direction of the manhole cover frame structure, or the radial width of the area in which the multiple prevention members are present, is the radial length of the manhole cover or manhole frame that corresponds to the dimensional variation caused by expected manufacturing errors of the manhole cover or manhole frame or thermal expansion or thermal contraction due to environmental conditions after construction.

With this configuration, even if there are dimensional variations in the manhole cover or manhole frame due to manufacturing errors or thermal expansion or contraction caused by environmental conditions after installation, the prevention member can be crushed and/or deformed more reliably to ensure that the manhole cover or manhole frame and the prevention member are in close contact with each other.

FIG. 2 is a perspective view of a manhole cover frame structure. This is a vertical cross-sectional view of a manhole cover frame structure when the manhole frame is relatively small compared to the manhole cover. This is a vertical cross-sectional view of a manhole cover frame structure when the manhole frame is relatively large compared to the manhole cover. FIG. 11 is a perspective view showing another embodiment of the prevention member. FIG. 11 is a perspective view showing another embodiment of the prevention member. FIG. 11 is a perspective view showing another embodiment of the prevention member. FIG. 1 is a vertical cross-sectional view of a conventional manhole cover frame structure.

[Embodiment]
Hereinafter, an embodiment of the present invention will be described.
As shown in FIG. 1, the manhole cover frame structure 1 in this embodiment comprises a manhole cover 2 and a manhole frame 3 into which the manhole cover 2 is fitted.

The manhole cover 2 is a circular disk-shaped cover with an edge 20 hanging down from the periphery.

The manhole frame 3 is a ring-shaped frame with a fitting groove 30 formed around its periphery. When the manhole cover 2 is attached to the manhole frame 3, the edge 20 of the manhole cover 2 is configured to fit into the fitting groove 30.

In this embodiment, the fitting groove 30 of the manhole frame 3 is provided with a vertical rib A that extends radially from the radially inner side surface 31 to the bottom surface 33. In this embodiment, the vertical rib A is integrally molded with the manhole frame 3, but is not limited to this configuration.

When the manhole cover 2 is fitted into the manhole frame 3, the vertical rib A is crushed and/or deformed to bring the manhole cover 2 into close contact with the vertical rib A, thereby functioning as a preventive member to prevent lateral movement of the manhole cover 2 relative to the manhole frame 3.

As shown in FIG. 2, when the manhole frame 3 is relatively small compared to the manhole cover 2, the gap 40 between the outer inclined surface 22 of the manhole cover 2 and the radially outer side surface 32 of the manhole frame 3 is small, and the manhole cover 2 is less likely to wobble laterally. In this case, the inner inclined surface 21 of the edge portion 20 of the manhole cover 2 is prevented from coming into contact with the vertical rib A.

On the other hand, if the manhole frame 3 is relatively large compared to the manhole cover 2, a relatively large gap 40 may occur between the outer inclined surface 22 of the manhole cover 2 and the radially outer side surface 32 of the manhole frame 3. As a result, especially immediately after the manhole cover 2 is attached to the manhole frame 3, surrounding gravel and the like has not entered the gap, so there is little friction because there is no contamination of foreign matter such as gravel at the contact surface between the manhole cover and the manhole frame or damage to the contact surface. When vibration or the like is applied, the manhole cover 2 is likely to rattle laterally, and further, the manhole cover may rotate in the circumferential direction due to external forces such as the momentum of an operator placing his foot on it.

However, according to the manhole cover frame structure 1 of this embodiment, as shown in FIG. 3, when the manhole cover 2 is attached to the manhole frame 3, the inner inclined surface 21 of the edge 20 of the manhole cover 2 comes into contact with the vertical rib A. At this time, part of the vertical rib A is crushed so as to be scraped off, and/or part of the vertical rib A is deformed, so that the edge 20 of the manhole cover 2 and the fitting groove 30 of the manhole frame 3 are tightly attached to each other. As a result, rattling due to lateral movement of the manhole cover 2 relative to the manhole frame 3 and rotation in the circumferential direction are prevented.

The shape of the vertical rib A, which is a preventive member, is preferably such that the gradient of the vertical rib A facing the inner inclined surface 21 of the edge 20 of the manhole cover 2 is the same as or steeper than the gradient of the inner inclined surface. When the manhole cover 2 is fitted into the manhole frame 3, the contact area between the edge 20 of the manhole cover 2 and the vertical rib A is minimized, making it easy to position the edge 20 of the manhole cover 2 for insertion into the fitting groove 30 of the manhole frame 3.

It is preferable that the tip R2 of the vertical rib A, which is the prevention member, is formed in an arc shape. This makes it easier to insert the manhole cover 2 into the manhole frame 3.

In addition, it is preferable that the shape of the cover edge root portion R1 of the edge portion 20 of the manhole cover 2 forms an arc shape, and the curvature of the cover edge root portion R1 of the edge portion 20 of the manhole cover 2 and the curvature of the tip portion R2 of the vertical rib A, which is a preventive member, are R1>R2. When the manhole cover 2 is fitted into the manhole frame 3, the cover edge root portion R1 of the edge portion 20 of the manhole cover 2 and the tip portion R2 of the vertical rib A come into contact, and the pressure of the cover edge root portion R1 causes the tip portion R2 of the vertical rib A to be crushed and/or deformed and adhere closely, thereby reliably suppressing rattling and rotation of the manhole cover relative to the manhole frame.

The inner inclined surface 21 of the edge 20 of the manhole cover 2 may be textured or otherwise configured to increase the coefficient of friction. This makes it even easier to prevent the manhole cover 2 from rotating.

It is desirable to provide three or more vertical ribs A of the same shape at equal intervals around the circumference. This makes it easier to fit the manhole cover 2 so that its central axis coincides with the central axis of the manhole frame 3 when attaching the manhole cover 2 to the manhole frame 3.

The width of the vertical rib A may be set appropriately depending on the ease of crushing and/or deformation, but it is desirable to set the radial length of the vertical rib A to the radial length of the manhole cover 2 or manhole frame 3 that corresponds to the expected manufacturing error of the manhole cover 2 or manhole frame 3 or the dimensional variation caused by thermal expansion or thermal contraction due to environmental conditions after installation. The maximum radial length of the vertical rib A is the radial length of the fitting groove 30 of the manhole frame 3 minus the radial length of the edge portion 20 of the manhole cover 2.

Constituent materials applicable to the manhole cover 2 and manhole frame 3 of the present invention include, for example, synthetic resins such as polypropylene resin (PP), but are not limited thereto as long as they are configured so that the vertical ribs A are crushed and/or deformed when the manhole cover 2 is attached to the manhole frame 3.

Other Embodiments
1. In the above embodiment, the shape of the prevention member is shown as a vertical rib A extending in the radial direction, but the shape is not limited to this as long as the shape can be crushed and/or deformed when the manhole cover 2 is attached to the manhole frame 3. For example, as shown in Fig. 4, a vertical rib A extending in the circumferential direction may be used, as shown in Fig. 5, a configuration in which multiple vertical ribs A extending in the circumferential direction are provided, or as shown in Fig. 6, a configuration in which multiple cylindrical ones are provided. In addition, in the case of the configuration shown in Fig. 5 and Fig. 6, it is preferable to set the length of the radial width W of the area in which the multiple prevention members A exist to the radial length of the manhole cover 2 or manhole frame 3 equivalent to the expected manufacturing error of the manhole cover 2 or manhole frame 3 or the dimensional variation caused by thermal expansion or thermal contraction due to environmental conditions after installation.

2. In the above embodiment, the vertical rib A, which is the prevention member, is configured to extend from the radially inner side surface 31 to the bottom surface 33 of the fitting groove 30 of the manhole frame 3, but this configuration is not limited to this. The prevention member may be configured to extend from the radially outer side surface 32 to the bottom surface 33 of the fitting groove 30 of the manhole frame 3, or may be configured on both sides of the fitting groove 30.

3. In the above embodiment, the prevention member is provided in the fitting groove of the manhole frame, but the present invention is not limited to this configuration, and the prevention member may be provided on the edge of the manhole cover. In this case, for example, the prevention member may be provided on the inner surface or outer surface of the edge of the manhole cover, or on both sides thereof.

4. The manhole cover frame structure of the present invention can be applied to, for example, manholes in septic tanks, and is particularly suitable for use in small and medium-sized septic tanks.

The configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, provided no contradictions arise. Furthermore, the embodiments disclosed in this specification are merely examples, and the present invention is not limited to these embodiments. Appropriate modifications can be made without departing from the scope of the present invention.

The present invention can be suitably used in the field of technology to suppress rattling and rotation of manhole covers for septic tanks, for example.

1 Manhole cover frame structure 2 Manhole cover 20 Edge portion 21 Inner inclined surface 22 Outer inclined surface 3 Manhole frame 30 Fitting groove 31 Radially inner side surface 32 Radially outer side surface 33 Bottom surface 40 Gap (gap between the outer inclined surface 22 and the radially outer side surface 32)
A. Vertical rib (an example of a prevention member)
R1 Lid edge root portion (root portion of the edge portion 20 of the manhole cover 2)
R2 Tip (tip of vertical rib A)
G Rubber plate W Radial width

Claims (4)

A manhole cover frame structure comprising a manhole cover having an edge portion hanging down from a periphery thereof and a manhole frame having a fitting groove into which the edge portion of the manhole cover is fitted,
When the manhole cover is fitted to the manhole frame, a preventing member that prevents the manhole cover from moving laterally relative to the manhole frame by being crushed is provided on at least one of an edge of the manhole cover and a fitting groove of the manhole frame ,
A manhole cover frame structure, characterized in that the prevention member is integrally provided when forming the manhole cover or the manhole frame . The manhole cover frame structure according to claim 1, characterized in that the shape of the prevention member is selected from the group consisting of a radially extending vertical rib shape, a circumferentially extending vertical rib shape, and a cylindrical shape. The manhole cover frame structure according to claim 2, characterized in that the shape of the prevention member is a vertical rib extending in the radial direction, and the prevention member is provided in a fitting groove of the manhole frame. The manhole cover frame structure according to any one of claims 1 to 3, characterized in that the radial length of the prevention member or the radial width of the area in which a plurality of the prevention members are present is the radial length of the manhole cover or the manhole frame that corresponds to the dimensional variation caused by manufacturing errors of the manhole cover or the manhole frame or thermal expansion or thermal contraction due to environmental conditions after installation.

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