JP6842831B2 - Flush toilet - Google Patents

Description

The present invention relates to a flush toilet.

In Patent Document 1, a toilet drainage pipe portion extending from the lower end portion of the toilet bowl portion is housed in the toilet bowl body of the flush toilet, and protrudes from the downstream end of the toilet bowl drainage pipe portion and the wall surface of the toilet room. A structure for connecting the upstream end of a drainage pipe via a drainage connection member is disclosed. The drainage connection member is arranged so as to penetrate the opening formed in the rear wall portion of the toilet bowl body. The upstream end of the drainage connection member is connected to the downstream end of the toilet drainage pipe portion in the toilet body. On the other hand, the downstream end of the drainage connection member is connected to the upstream end of the drainage pipe outside the toilet body.

Japanese Patent No. 5420608

In the above connection structure, since the toilet bowl body is located in front of the upstream end of the drain pipe, the above-mentioned dimension from the wall surface of the toilet room to the front end of the flush toilet bowl becomes large. Since the space between the wall surface and the rear end of the toilet bowl body is a dead space, it is preferable to arrange the toilet bowl body near the wall surface in order to effectively use the space in the toilet room.

The present invention has been made in view of the above-mentioned conventional circumstances, and it is an object to be solved that the toilet bowl main body can be arranged near the wall surface of the toilet room.

The flush toilet of the present invention
A flush toilet that is installed on the floor of the toilet room away from the wall surface of the toilet room.
A toilet bowl main body having a toilet bowl portion and a toilet bowl drainage pipe portion extending from the toilet bowl portion and having a connection space inside.
A part of the peripheral wall portion forming both the left and right outer peripheral surfaces of the toilet bowl body, and an outer wall portion for partitioning the outside of the toilet bowl body and the connection space.
An opening formed in the outer wall portion and penetrating a drainage pipe protruding from the wall surface of the toilet room,
It is provided with a drainage connection member housed in the connection space.
The drainage connection member has a tubular body having a quarter arc shape and has a tubular body.
At one open end of the tubular body, an upstream connection pipe portion located in the connection space and connected to the downstream end of the toilet drainage pipe portion is formed.
At the other open end of the tubular body, a downstream connection pipe portion located in the connection space and connectable to the upstream end of the drainage pipe is formed .
The entire downstream connection pipe portion is housed in the connection space .

Since the outer wall of the toilet bowl is formed with an opening through which the drainage pipe protrudes from the wall surface of the toilet room, the upstream end of the drainage pipe is located in the connection space of the toilet bowl body. Then, in this connection space, the downstream connection pipe portion of the drainage connection member is connected to the upstream end of the drainage pipe. According to this connection form, the toilet body can be installed closer to the wall surface of the toilet room than the one connected to the drain pipe outside the toilet body.

Perspective view of the flush toilet of Example 1 Cross-sectional view of a flush toilet connected to a drain pipe Partially enlarged cross-sectional view of FIG. Perspective view of drainage connection member Perspective view showing the state where the shielding member is attached to the drain pipe Perspective view showing the state where the shielding member is removed from the drain pipe Perspective view of the shielding member

In the flush toilet of the present invention, the toilet body may be made of a non-combustible material, and the gap between the opening and the outer periphery of the drain pipe may be closed with a non-combustible shielding member. When the flame in the drain pipe melts the drain connection member and enters the connection space, the flame in the connection space leaks to the outside of the toilet bowl body through the gap between the opening and the outer peripheral surface of the drain pipe. Is a concern. However, since the gap between the opening and the outer peripheral surface of the drain pipe is closed with a shielding member, it is possible to prevent the flame from leaking to the outside of the toilet bowl body.

The flush toilet of the present invention may include a sealing member in which the shielding member can elastically contact the outer periphery of the drainage pipe. According to this configuration, it is possible to prevent a gap from being generated between the seal member and the outer periphery of the drain pipe.

In the flush toilet of the present invention, the sealing member may be in elastic contact with the inner peripheral surface of the opening. According to this configuration, it is possible to prevent a gap from being formed between the seal member and the inner circumference of the opening.

<Example 1>
Hereinafter, Example 1 embodying the present invention will be described with reference to FIGS. 1 to 7. In the following description, the right side in FIG. 2 is defined as the front in the front-rear direction. As shown in FIG. 2, the flush toilet A of the first embodiment is installed on the floor surface F in the toilet room T, and is connected to the drain pipe 10 protruding horizontally forward from the wall surface W of the toilet room T. It is a thing.

<Drainage pipe 10>
The drainage pipe 10 has a two-layer structure composed of an inner cylinder 11 having a circular cross section made of a synthetic resin material and an outer cylinder 12 having a circular cross section made of a refractory material. As shown in FIG. 3, the protruding regions of the drainage pipe 10 from the wall surface W are the base end side pipe portion 13 (rear end portion) near the wall surface W and the inflow pipe portion 14 (front end portion) farthest from the wall surface W. It is composed of an intermediate pipe portion 15 between the base end side pipe portion 13 and the inflow pipe portion 14. The outer diameter of the base end side pipe portion 13 is smaller than the outer diameter of the inflow pipe portion 14. The outer diameter of the intermediate pipe portion 15 gradually increases from the base end side pipe portion 13 toward the inflow pipe portion 14.

<Flush toilet A>
As shown in FIG. 2, the flush toilet A is configured to include a refractory toilet body 20, a drainage connecting member 40, and a refractory shielding member 50. The toilet bowl body 20 is made of pottery and is a single member including a pedestal portion 21, a toilet bowl portion 28, and a toilet bowl drainage pipe portion 30. The pedestal portion 21 includes a peripheral wall portion 22 that constitutes the front-rear and left-right outer peripheral surfaces of the toilet bowl main body 20, and an upper surface portion 23 that projects inward from the upper end edge of the peripheral wall portion 22.

Of the peripheral wall portions 22, the rear wall portion 24 (the outer wall portion according to claim) constituting the rear surface of the toilet bowl body 20 is formed with an opening 25 in the form of being open at the lower end edge of the rear wall portion 24. .. The opening 25 penetrates from the outer surface to the inner surface of the rear wall portion 24. As shown in FIG. 1, the upper end side portion of the rear view opening region of the opening 25 is a substantially semicircular arched opening region 26. The radius of curvature of the opening edge of the arched opening region 26 is larger than the radius of curvature of the outer circumference of the inflow pipe portion 14. Further, the portion of the rear view opening region of the opening 25 below the arch-shaped opening region 26 is a square opening region 27 having the same width as the arch-shaped opening region 26. The height dimension of the square opening region 27 is larger than the outer diameter (diameter) of the inflow pipe portion 14.

<Toilet bowl 28>
As shown in FIG. 2, the toilet bowl portion 28 is housed inside the pedestal portion 21, and the upper end edge of the toilet bowl portion 28 is connected to the inner peripheral edge of the upper surface portion 23. Of the inside of the pedestal portion 21, the space partitioned by the inner surface of the peripheral wall portion 22 and the lower surface of the toilet bowl portion 28 and the upper surface portion 23 is an open connection over the entire lower surface area of the toilet bowl body 20 (pedestal portion 21). It is a space 29. The connection space 29 is isolated from the outside of the toilet bowl body 20 and can communicate with the outside of the toilet bowl body 20 through the opening 25. In addition, according to the technical concept of this embodiment, the opening 25 is included in the connection space 29.

<Toilet bowl drain pipe section 30>
The toilet bowl drainage pipe portion 30 has a form extending from the lower end portion (downstream end portion) of the toilet bowl portion 28, and is housed inside the connection space 29. The toilet bowl drainage pipe portion 30 is composed of an ascending pipe portion 31 connected to the lower end portion of the toilet bowl portion 28 and a descending pipe portion 32 connected to the upper end portion of the ascending pipe portion 31. The lower end portion of the descending pipe portion 32 (the downstream end portion of the toilet bowl drainage pipe portion 30) is an outflow pipe portion 33 that opens downward. The outflow pipe portion 33 is arranged behind the toilet bowl portion 28, and is arranged at the rear end portion (that is, a position close to the opening 25) in the connection space 29.

<Drainage connection member 40>
As shown in FIGS. 3 and 4, the drainage connecting member 40 is configured by assembling a tubular main body 41 made of synthetic resin, a pedestal-shaped fixing member 45 made of synthetic resin, and a connecting ring 47. The tubular main body 41 is a tubular body having a substantially circular cross section, and the side view shape is a substantially quarter arc shape. One open end of the tubular body 41 is located at the front end of the drainage connecting member 40, and is an upstream connecting pipe portion 42 whose axis is opened upward in the vertical direction. The other open end of the tubular body 41 is located at the rear end of the drainage connecting member 40, and is a downstream connecting pipe portion 43 whose axis is opened rearward in the front-rear direction.

The tubular main body 41 is formed with a tubular leg portion 44 having a shape protruding downward from the outer surface of the lower end portion thereof. The fixing member 45 is formed with a tubular mounting portion 46 whose axis is directed in the vertical direction, and a tubular leg portion 44 is fitted in the tubular mounting portion 46. A connecting ring 47 is screwed into the upper end of the tubular mounting portion 46. When the connecting ring 47 is tightened, as shown in FIG. 3, the packing 49 attached so as to be sandwiched between the connecting ring 47 and the tubular mounting portion 46 is reduced in diameter and deformed to the outer circumference of the tubular leg portion 44. The fixing member 45 and the tubular main body 41 are assembled and integrated by the close contact.

The fixing member 45 of the drainage connecting member 40 is fixed to the floor surface F by bolts (not shown). The drainage connection member 40 is attached to the toilet bowl main body 20 by connecting the upstream side connection pipe portion 42 to the outer circumference of the outflow pipe portion 33 of the toilet bowl drainage pipe portion 30 in a liquidtight and coaxial manner. The downstream connecting pipe portion 43 of the drainage connecting member 40 is connected to the inner circumference of the inflow pipe portion 14 of the drainage pipe 10 in a liquidtight and coaxial manner via the packing 48. That is, the drainage connection member 40 connects the toilet bowl drainage pipe portion 30 of the toilet bowl main body 20 and the drainage pipe 10 protruding from the wall surface W of the toilet room T.

<Positional relationship between drainage pipe 10 and toilet bowl body 20>
The drainage pipe 10 penetrates the opening 25 of the rear wall portion 24 so as to be coaxial with the arch-shaped opening region 26. Specifically, the entire base end side pipe portion 13 of the drainage pipe 10 is located behind the rear wall portion 24 (that is, outside the toilet bowl main body 20). The region of the intermediate pipe portion 15 of the drainage pipe 10 excluding the front end portion is located behind the outer surface of the rear wall portion 24. The front end of the intermediate pipe portion 15 and the rear end of the inflow pipe portion 14 are located within the plate thickness range of the rear wall portion 24 (that is, within the range of the opening 25).

The region of the inflow pipe portion 14 in front of the rear end portion is located in the region of the connection space 29 in front (inside) of the inner surface of the rear wall portion 24. On the other hand, the entire drainage connecting member 40 including the downstream connecting pipe portion 43 is housed in a region of the connecting space 29 in front (inside) of the inner surface of the rear wall portion 24. Therefore, the entire connection portion between the drainage pipe 10 and the drainage connection member 40 (the region where the inflow pipe portion 14 and the downstream connection pipe portion 43 overlap in the radial direction) is the inner surface of the rear wall portion 24 of the connection space 29. It is housed in the area in front of (inside).

<Shielding member 50>
As described above, since the inner diameter of the arched opening region 26 of the opening 25 of the rear wall portion 24 is larger than the outer diameter of the inflow pipe portion 14 of the drain pipe 10, the inner circumference of the opening 25 and the outer circumference of the drain pipe 10 There will be a gap between them. If this gap is left open, when the flame in the drain pipe 10 melts the drainage connecting member 40 made of synthetic resin and invades the connection space 29 in the event of a fire, the flame in the connection space 29 will be generated. There is a risk of leakage to the outside of the toilet bowl body 20 (that is, inside the toilet room T) through the gap between the opening 25 and the drain pipe 10.

As a countermeasure, the flush toilet A of the present embodiment is provided with a nonflammable shielding member 50 as a means for closing the gap between the drain pipe 10 and the opening 25. The shielding member 50 is configured by assembling a sealing member 51, a metal shielding plate 54, and a pair of left and right metal fixing arms 55.

The seal member 51 is formed by surrounding an elastic nonflammable material (for example, glass wool, rock wool, ceramic wool, etc.) formed into a predetermined shape with a nonflammable exterior material such as aluminum foil. As shown in FIGS. 6 and 7, the seal member 51 includes a ring-shaped seal portion 52 having a ring shape, and a pair of left and right leg-shaped seal portions extending downward from both left and right ends of the ring-shaped seal portion 52 in a cantilever shape. It is composed of 53. The radius dimension of the outer circumference of the ring-shaped seal portion 52 is set to be larger than the radius of curvature of the arch-shaped opening region 26 of the opening portion 25. The inner diameter of the ring-shaped seal portion 52 is set to be smaller than the outer diameter of the inflow pipe portion 14.

The shield plate 54 has a shape in which the upper end portion of the square is cut out in a substantially semicircular shape. A pair of left and right leg-shaped seal portions 53 are adhered to the left and right side edges of the front surface of the shielding plate 54 with a nonflammable adhesive (not shown). The lower half region of the ring-shaped sealing portion 52 is adhered to the upper end edge portion forming a substantially semicircular arc shape on the front surface of the shielding plate 54 with a nonflammable adhesive (not shown). The pair of left and right fixing arms 55 are fixed to the lower end edge of the shielding plate 54 at a position near the leg-shaped sealing portion 53 by welding or the like. The fixed arm 55 has a cantilevered shape extending forward from the shielding plate 54.

The fixing arm 55 of the shielding member 50 is fixed to the floor surface F by bolts (not shown). The shielding member 50 is attached to the drain pipe 10 in a state where the ring-shaped seal portion 52 is elastically fitted to the outer periphery of the rear end portion of the inflow pipe portion 14 and the front end portion of the intermediate pipe portion 15. Further, the shielding member 50 elastically fits the upper half region of the ring-shaped seal portion 52 into the inner peripheral surface of the arch-shaped opening region 26, and the outer surface of the leg-shaped seal portion 53 is inside the square opening region 27. It is attached to the rear wall portion 24 of the toilet bowl body 20 in a state of being elastically contacted with the side surface. Further, the shielding plate 54 is positioned so as to close the opening region (square opening region 27) between the drain pipe 10 and the floor surface F in the opening 25.

Since the inner diameter of the ring-shaped seal portion 52 is set to be smaller than the outer diameter of the inflow pipe portion 14 of the drain pipe 10, the inner peripheral surface of the ring-shaped seal portion 52 covers the entire circumference of the inflow pipe portion 14. It is in close contact with the outer circumference elastically. Further, since the radius of the outer circumference of the ring-shaped seal portion 52 is set to be larger than the radius of curvature of the arch-shaped opening region 26, the inner circumference of the arch-shaped opening region 26 is below the ring-shaped seal portion 52 (that is, the inflow pipe). Press to the portion 14 side). Then, by this pressing action, the upper half region of the ring-shaped seal portion 52 is pressed against the outer circumference of the inflow pipe portion 14.

<Action and effect of Examples>
The flush toilet A having the above configuration is assembled as follows. First, the shielding member 50 is attached to the drain pipe 10 from the front, and the ring-shaped seal portion 52 is fitted onto the inflow pipe portion 14. At this time, the installation position of the drainage connection member 40 on the floor surface F is confirmed, and a position separated from this installation position by a certain dimension is set as the installation position of the shielding member 50. After positioning the shielding member 50 with respect to the drain pipe 10, the fixing arm 55 is fixed to the floor surface F. Next, the drainage connecting member 40 is assembled to the drainage pipe 10 from the front thereof, and the packing 48 and the downstream connecting pipe portion 43 are internally fitted into the inflow pipe portion 14. After positioning the drainage connection member 40 with respect to the drainage pipe 10, the fixing member 45 is fixed to the floor surface F.

After that, the toilet bowl main body 20 is put on the drain pipe 10, the shielding member 50, and the drain connecting member 40 from above. At this time, the outflow pipe portion 33 of the toilet bowl drainage pipe portion 30 is fitted onto the upstream side connecting pipe portion 42 of the drainage connecting member 40, and the seal member 51 is brought into close contact with the inner peripheral surface and the inner side surface of the opening 25. Finally, if the toilet bowl body 20 is fixed to the floor surface F, the assembling work of the toilet bowl body 20, the drainage connecting member 40, and the shielding member 50 is completed.

As described above, the flush toilet A of the present embodiment includes a toilet body 20 and a drainage connecting member 40. The toilet bowl main body 20 has a toilet bowl portion 28 and a toilet bowl drainage pipe portion 30 extending from the toilet bowl portion 28, and a connection space 29 is provided inside the toilet bowl main body 20. The toilet bowl body 20 has a rear wall portion 24 that partitions the outside of the toilet bowl body 20 and the connection space 29. The rear wall portion 24 is formed with an opening 25 through which a drain pipe 10 projecting horizontally from the wall surface W of the toilet room T is penetrated. Further, the flush toilet A includes a drainage connecting member 40 housed in the connection space 29 in a state of being connected to the downstream end of the toilet bowl drainage pipe portion 30. The drainage connection member 40 is formed so that a downstream connection pipe portion 43 that can be connected to the upstream end (inflow pipe portion 14) of the drainage pipe 10 is located in the connection space 29.

Since an opening 25 is formed in the outer wall portion of the toilet bowl body 20 to penetrate the drainage pipe 10 protruding from the wall surface W of the toilet room T, the upstream end (inflow pipe portion 14) of the drainage pipe 10 is the toilet bowl body. It is located in the connection space 29 of 20. Then, in the connection space 29, the downstream connection pipe portion 43 of the drainage connection member 40 is connected to the inflow pipe portion 14 of the drainage pipe 10. According to this connection form, the toilet body 20 can be installed closer to the wall surface W of the toilet room T than the one connected to the drain pipe 10 outside the toilet body 20. Further, the entire circumference of the front end portion of the inflow pipe portion 14 is arranged in the connection space 29 (inside the outer surface of the rear wall portion 24), and the joint between the drain pipe 10 and the drainage connection member 40 is inside the connection space 29. Because it is hidden in, it has a high design.

Further, the toilet bowl body 20 is made of a non-combustible material, and the gap between the opening 25 and the outer periphery of the drain pipe 10 is closed with a non-combustible shielding member 50. According to this configuration, when the flame in the drainage pipe 10 melts the drainage connection member 40 and invades the connection space 29, the flame in the connection space 29 reaches the opening 25 and the outer peripheral surface of the drainage pipe 10. There is a concern that the water leaks to the outside of the toilet bowl body 20 through the gap between the two. However, since the gap between the opening 25 and the outer peripheral surface of the drain pipe 10 is closed by the shielding member 50, it is possible to prevent the flame from leaking to the outside of the toilet bowl main body 20 (that is, the toilet room T).

Further, since the shielding member 50 includes the sealing member 51 that can elastically contact the outer periphery of the drainage pipe 10, it is possible to prevent a gap from being generated between the sealing member 51 and the outer periphery of the drainage pipe 10. Moreover, since the seal member 51 elastically contacts the inner peripheral surface of the opening 25, it is possible to more reliably prevent a gap from being formed between the seal member 51 and the inner peripheral surface of the opening 25. Further, the thickness dimension (dimension in the front-rear direction) of the ring-shaped seal portion 52 is set to be larger than the thickness of the rear wall portion 24. As a result, when the toilet bowl body 20 is covered from above the ring-shaped seal portion 52, the positional relationship between the ring-shaped seal portion 52 and the opening 25 can be easily visually observed, which is excellent in workability.

<Other Examples>
The present invention is not limited to the examples described by the above description and drawings, and for example, the following examples are also included in the technical scope of the present invention.
(1) In the above embodiment, the shielding member includes a sealing member that can elastically contact the outer circumference of the drain pipe and the inner circumference of the opening, but the sealing member may be a rigid body having no elasticity. Good.
(2) In the above embodiment, the seal member is in elastic contact with both the outer circumference of the drain pipe and the inner circumference of the opening, but the seal member is either the outer circumference of the drain pipe or the inner circumference of the opening. Elastic contact may be made with only one of them. In this case, the inner diameter of the ring-shaped seal portion is smaller than the outer diameter of the inflow pipe portion, and the radius of the outer circumference of the ring-shaped seal portion is smaller than the radius of curvature of the arch-shaped opening region of the opening, or the ring. The radius of the outer circumference of the shaped seal portion may be larger than the radius of curvature of the arched opening region of the opening, and the inner diameter of the ring-shaped seal portion may be larger than the outer diameter of the inflow pipe portion. Further, the seal member may come into contact with both the outer circumference of the drain pipe and the inner circumference of the opening with almost no elastic deformation. In this case, the inner diameter of the ring-shaped seal portion may be substantially the same as the outer diameter of the inflow pipe portion, and the radius of the outer circumference of the ring-shaped seal portion may be substantially the same as the radius of curvature of the arch-shaped opening region of the opening.
(3) In the above embodiment, the opening is opened to the lower end edge of the outer wall portion, but the opening is not opened to the lower end edge of the outer wall portion, and the opening edge is all around like a window hole. It may be in a closed form.
(4) In the above embodiment, the seal member of the shielding member is brought into contact with the inner peripheral surface of the opening, but the seal member may be brought into contact with the opening edge of the opening among the outer or inner surfaces of the outer wall portion. ..
(5) In the above embodiment, the drainage connecting member and the shielding member manufactured as separate members are attached to the toilet bowl body and the drainage pipe in separate steps, but the present invention is not limited to this, and the drainage connecting member and the shielding member are attached in advance. It may be assembled and modularized. In this case, only one of the drainage connecting member and the shielding member may be fixed to the floor surface of the toilet room.
(6) In the above embodiment, the drainage pipe protrudes forward, but the present invention can also be applied to the case where the drainage pipe protrudes sideways.
(7) In the above embodiment, the front end portion of the intermediate pipe portion of the drainage pipe and the rear end portion of the inflow pipe portion are located within the range of the plate thickness of the rear wall portion, but the rear wall portion and the drainage pipe are located. The positional relationship with is not limited to this. That is, only the intermediate pipe portion may be located within the range of the plate thickness of the rear wall portion, or the front end portion of the base end side pipe portion and the rear end portion of the intermediate pipe portion may be located. , Only the inflow pipe portion may be located.
(8) In the above embodiment, the entire connection portion between the drain pipe and the drain connection member is housed in the area of the connection space in front of the inner surface of the rear wall portion, but the present invention is not limited to this, and the drain pipe and drainage are not limited to this. A part of the connecting portion of the connecting member may be arranged outside the connection space (region behind the outer surface of the rear wall portion) or inside the opening which is the plate thickness range of the rear wall portion.
(9) In the above embodiment, the installation position of the drainage connection member and the installation position of the shielding member on the floor surface are set to different positions, but the installation position of the drainage connection member and the installation position of the shielding member overlap each other. May be set to, and the drainage connecting member and the shielding member may be fixed to the floor surface by co-tightening.

A ... Flush toilet T ... Toilet room W ... Wall surface 10 ... Drainage pipe 14 ... Inflow pipe (upstream end of drainage pipe)
20 ... Toilet bowl body 24 ... Rear wall (outer wall)
25 ... Opening 28 ... Toilet bowl 29 ... Connection space 30 ... Toilet drainage pipe 33 ... Outflow pipe (downstream end of toilet drainage pipe)
40 ... Drainage connection member 43 ... Downstream connection pipe part 50 ... Shielding member 51 ... Seal member

Claims (4)

A flush toilet that is installed on the floor of the toilet room away from the wall surface of the toilet room.
A toilet bowl main body having a toilet bowl portion and a toilet bowl drainage pipe portion extending from the toilet bowl portion and having a connection space inside.
A part of the peripheral wall portion forming both the left and right outer peripheral surfaces of the toilet bowl body, and an outer wall portion for partitioning the outside of the toilet bowl body and the connection space.
An opening formed in the outer wall portion and penetrating a drainage pipe protruding from the wall surface of the toilet room,
It is provided with a drainage connection member housed in the connection space.
The drainage connection member has a tubular body having a quarter arc shape and has a tubular body.
At one open end of the tubular body, an upstream connection pipe portion located in the connection space and connected to the downstream end of the toilet drainage pipe portion is formed.
At the other open end of the tubular body, a downstream connection pipe portion located in the connection space and connectable to the upstream end of the drainage pipe is formed .
A flush toilet in which the entire downstream connection pipe portion is housed in the connection space. The body of the toilet bowl is made of non-combustible material
The flush toilet according to claim 1, wherein the gap between the opening and the outer periphery of the drain pipe is closed with a nonflammable shielding member. The flush toilet according to claim 2, wherein the shielding member includes a sealing member that can elastically contact the outer periphery of the drain pipe. The flush toilet according to claim 3, wherein the sealing member is elastically in contact with the inner peripheral surface of the opening.

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