JPH11311452A - Circulation fitting for bathtub - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circulation fitting which can prevent the falling of a filter and have a good appearance. SOLUTION: A circulation fitting for a bathtub includes a sleeve 23 which is mounted on a side wall of a bathtub, a circulation opening body 30 fitted into the sleeve 23 and a filter case 43 fitted on the circulation opening body 30. The circulation opening body 30 is provided with a pair of opening portions 39a, 39b which function as an inlet opening and an outlet opening for bathtub water. On a circumferential wall of a filter case 43 which corresponds to a pair of opening portions 39a, 39b, a pair of through holes 45 are formed. A filter 47a is fitted into the through hole 45 which corresponds to the opening portion 39a which functions as the inlet opening such that the filter 47a is replaceably mounted on the inner peripheral wall of the filter case 43.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bathtub which is attached to a side wall of a bathtub, sucks and moves bathtub water toward a heater,
The present invention relates to a bathtub circulator for discharging bathtub water heated in a heater into a bathtub.

[0002]

2. Description of the Related Art Generally, a bathtub circulating device includes a cylindrical sleeve fitted and fixed in a mounting hole provided in a side wall of a bathtub, and a substantially cylindrical circulation port main body fitted into the sleeve. It is configured.

[0003] On the peripheral surface of the circulation port main body, a pair of openings that open diagonally downward from each other are formed, and each opening is connected to a suction conduit and a discharge conduit of a heater outside the bathtub. It functions as a suction port or a discharge port.

[0004] The filter case fitted to the circulation port main body is formed in a cylindrical shape having a bottom with metal, and its front surface is opened over almost the entire area, and a wire mesh is attached so as to cover this opening. ing. Further, a pair of through holes are formed through the peripheral wall of the filter case corresponding to the suction port and the discharge port. A filter made of a wire mesh is attached to the pair of through holes, so that entry of foreign matter into the heater can be prevented.

However, in the case of a so-called non-polar bathtub circulation port having the above-described structure, it is impossible to determine which of the pair of openings becomes the discharge port until the opening is connected to the heater. ing. At the discharge port, the heated bathtub water is not completely discharged due to the attachment of foreign matter to the filter or the like, and the undischarged bathtub water is connected to the unheated bathtub water on the suction port side and the circulation port. May be mixed in the body. And, by this mixed bath water being sent to the heater, the heater is
In some cases, it was erroneously recognized that the bath water in the bath reached a predetermined temperature, and the heating was stopped (short cycle).

In order to solve this problem, there is a conventional method in which a filter is detachably mounted on an outer peripheral wall of a filter case. After the filter case is fitted to the circulation port main body, a filter that solves the above problem by removing the filter on the side serving as the discharge port is used.

[0007]

However, when the filter is detachably mounted on the outer peripheral wall of the filter case as in the prior art, since the filter protrudes from the peripheral wall of the filter case, the user's feet and the like may be disturbed. Due to this, there is a problem that the filter on the suction port side may fall off and the appearance may be deteriorated.

The present invention has been made by paying attention to such problems existing in the prior art. An object of the present invention is to provide a bathtub circulator capable of preventing the filter from falling off and having a good appearance.

[0009]

In order to achieve the above object, the invention of a bathtub circulator according to claim 1 is provided with a sleeve attached to a side wall of the bathtub and fitted to the sleeve. A circulation port main body, and a bottomed tubular filter case fitted to the circulation port main body, wherein the circulation port main body is connected to an external heater, and functions as a bathtub water suction port or discharge port. And a pair of through-holes are provided in the peripheral wall of the filter case corresponding to the pair of openings to prevent foreign matter from entering the through-hole corresponding to the suction port of the pair of openings. Is detachably mounted on the inner peripheral wall of the filter case.

[0010] The invention of the bathtub circulator according to claim 2 is as follows.
The invention according to claim 1, wherein the circulation port body between the pair of openings is provided with an isolating means for preventing the bathtub water to be sucked and the bathtub water to be discharged from mixing with each other. It is.

[0011] The invention of a bathtub circulator according to claim 3 is as follows.
The invention according to claim 1 or 2, wherein the bathtub water flowing from between the circulation port main body and the side wall of the bathtub is substantially prevented from flowing to the filter case side. .

The invention of the circulating device for a bathtub according to claim 4 is
The invention according to any one of claims 1 to 3, wherein the pair of openings are formed to have a substantially cylindrical shape.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. As shown in FIGS. 1 and 3, the rear case 13 attached to the outside of the side wall 12 of the bathtub is formed in a substantially bottomed cylindrical shape by metal. The cylindrical communication pipe 14 is provided in the rear case 13 so as to extend from the inner bottom surface of the rear case 13, and is connected to the rear case 13 by the communication pipe 14.
Is partitioned into a central inner chamber 15 and an outer peripheral chamber 16.

The two pipe connection ports 17a and 17b are attached to the rear end of the rear case 13, and one pipe connection port 17a is connected to the inner chamber 15 and the other pipe connection port 17b.
Communicates with the outside room 16. The two pipe connection ports 17a and 17b are connected to an inlet pipe 18 and a discharge pipe 19 extending from a heater (not shown), respectively, so that bath water can be circulated between the inner chamber 15 and the outer chamber 16 and the heater. It has become.

The annular flange 20 is connected to the rear case 13.
Is formed integrally with the rear case 13 on the opening side end face thereof, and a packing 21 formed of a synthetic rubber or the like and having a U-shaped cross section is fitted over the entire peripheral surface thereof. The female screw part 22 is threaded on the inner peripheral surface of the flange 20 at the opening end of the rear case 13.

As shown in FIG. 1 and FIG.
Is formed in a cylindrical shape by a synthetic resin or the like,
A male screw 24 is threaded on the outer peripheral surface. The sleeve 23 is inserted into the mounting hole 25 provided in the side wall 12 of the bathtub, and the male screw 24 and the rear case 1 are inserted.
The third female screw portion 22 is attached to the bathtub by screwing. The pair of protrusions 26 are formed on the inner peripheral surface of one end of the sleeve 23 so as to face each other. An annular fitting flange 27 is formed at one end of the sleeve 23 and has an engagement annular groove 28 on its outer peripheral surface.
Are formed. When the rear case 13 and the sleeve 23 are screwed together via the side wall 12 of the bathtub, the annular packing 29 is attached to the sleeve 23 so as to be sandwiched between the side wall 12 of the bathtub and the fitting flange 27. It is fitted.

The circulation port main body 30 is formed in a substantially cylindrical shape from a synthetic resin, and a cylindrical water passage pipe 31 is formed at the center of the back surface thereof.
A water passage opening 32 communicating with the inside of the circulation port main body 30 is formed at a position near the base end of the hole.

Positioning ring 33 composed of a plurality of uneven portions
Is formed on the back surface of the circulation port main body 30 so as to surround the base end of the water flow pipe 31. Then, as shown in FIG.
At the time of mounting, the pair of protrusions 26 of the sleeve 23 is engaged with the recess 33a of the positioning ring 33,
The circulation port main body 30 is positioned at a predetermined position while preventing rotation with respect to the sleeve 23.

As shown in FIGS. 1 and 10, a plurality of pairs of split grooves 34 extending from the back surface to the front surface of the circulation port body 30 are formed on the outer peripheral wall of the circulation port body 30 to a predetermined depth. An engaging claw 35 as a pressing means is formed integrally with the circulation port main body 30 between the portions 34. As shown in FIG. 5, the plurality of engaging claws 35 are formed so as to protrude from the outer peripheral wall of the circulation port main body 30 so as to have a substantially L-shaped cross section.
It has an inclined surface 35 a that is inclined so as to become lower toward the surface of the circulation port main body 30. The engagement protrusion 36 is provided with the engagement claw 35.
Is formed on the inner peripheral wall on the back surface of the circulation port main body 30 corresponding to.

As shown in FIGS. 6 and 7, when the circulation port main body 30 is mounted on the sleeve 23, the fitting flange 27 of the sleeve 23 is fitted on the back side of the circulation port main body 30. ing. At this time, the fitting flange 2
7 and the engagement protrusion 36 of the circulation port main body 30.
Are engaged.

As shown in FIGS. 1 and 10, a substantially annular recess 37 is formed on the inner peripheral side of the surface of the circulation port main body 30 by a predetermined depth. The plurality of partition walls 38 serving as separating means partition the recess 37 into a pair of left and right water-passing recesses 37a and two pairs of upper and lower separating recesses 37b at predetermined intervals. One of the water-recessed recesses 37a is opened on the peripheral wall side of the circulation port main body 30 and the other is opened on the surface side, so that bathtub water flows into the inside from the peripheral wall and the surface of the circulation port main body 30. Has become. Each isolation recess 37b
Are formed at equal intervals between the pair of water passage recesses 37a so as to form a fan shape, and prevent the bathtub water flowing into the pair of water passage recesses 37a from mixing with each other. I have.

A pair of cylindrical openings 39a, 39
b is provided so as to extend from the inner peripheral wall of the water-recessed recess 37 to the outer peripheral wall of the circulation port main body 30 in the pair of water-recessed recesses 37 so that the extending directions thereof form a C-shape. Is formed.

As shown in FIGS. 6 and 7, one opening 39a is formed so as to communicate with the water pipe 31 and the other opening 39b is formed in the back surface of the circulation port main body 30. It is formed so as to communicate with the water opening 32.

As shown in FIG. 3, the water pipe 31 connects the circulation port body 30 to the rear case 1 via a sleeve 23.
3, it is inserted into the communication pipe 14 and communicates with the inner chamber 15 of the rear case 13. That is, the one opening 39 a is connected to the one pipe connection port 17 through the water pipe 31 and the inner chamber 15 of the rear case 13.
a.

The water passage opening 32 communicates with the outer chamber 16 of the rear case 13 via the sleeve 23 when the circulation port main body 30 is attached to the rear case 13 via the sleeve 23. . That is, the other opening 39b
Is connected to the other pipe connection port 17b through the water passage opening 32 and the outer chamber 16 of the rear case 13.

At this time, an annular groove 40 is formed on the inner peripheral surface at the end of the communication pipe 14 and the annular groove 40 is formed.
Is fitted with an O-ring 41 to prevent the bathtub water from leaking from a gap formed between the communication pipe 14 and the water pipe 31. As shown in FIGS. 6 and 7,
The seal ring 42 is formed in an annular shape so as to form a horizontal T-shaped cross section by an elastic material such as synthetic rubber,
The outer peripheral side of the positioning ring 33 is joined to the back surface of the circulation port main body 30. And the seal ring 4
2 prevents leakage of bathtub water from a gap formed between the fitting flange 27 and the back surface of the circulation port main body 30.

As shown in FIGS. 1 and 2, the filter case 43 is made of a synthetic resin base 4 formed into a bottomed cylindrical shape.
It is formed by fitting a bottomed cylindrical metal case 43b on the surface of 3a. Filter case 4
3, a plurality of substantially triangular water holes 44 are provided at equal intervals in the circumferential direction, and a pair of through holes corresponding to the pair of openings 39 of the circulation port body 30 are formed on the peripheral wall. 45 are provided. The wire mesh 46 is
a and the case 43 b, and the water passage 44 is covered with the wire mesh 46.

As shown by a two-dot chain line in FIG.
4 is set to correspond to the size of each isolation recess 37. At the same time, the size of the water inlet 44 is such that bathtub water flows from the back side to the front side of the circulation port body 30 through the pair of split grooves 34 formed on the left and right sides of the engagement claw 35. It is set to substantially prevent.

As shown in FIG. 8 and FIG.
Is fitted with a pair of filters 47a and 47b.
The pair of filters 47a and 47b are formed in a rectangular frame shape by a synthetic resin, are formed to be bent along the peripheral wall of the filter case 43, and have an engaging groove 48 formed in the peripheral wall. A wire mesh 46 is mounted in the frame of one filter 47a, and
7b is left open.

The plurality of engaging projections 49 are formed on the base 43a on the peripheral wall of the through hole 45. And
The filters 47 a and 47 b are fitted by engaging the engagement grooves 48 and the engagement protrusions 49 from the inside of the filter case 43. At this time, one filter 47a having the wire mesh 46 is fitted into the through hole 45 corresponding to one opening 39a serving as a suction port, and the other filter is connected to the other opening 39b serving as a discharge port. It is fitted in the corresponding through hole 45. In addition, as shown in FIG.
The size of the through hole 45 is such that the peripheral edge thereof is
b is set to a size not to block.

As shown in FIGS. 2 and 6, the retaining projection 50 is formed at a predetermined distance on the inner periphery of the filter case 43. In addition, a substantially L-shaped planar retaining groove 51 is formed in the peripheral wall of the circulation port main body 30 between the engaging claws 35. The filter case 43 is prevented from falling out of the circulation port main body 30 by engaging the retaining protrusion 50 with the retaining groove 51 and rotating the filter case 43 by a predetermined angle in the circumferential direction.

As shown in FIG. 5, a plurality of engaging claws 35 as a pressing means are used to connect the filter case 43 to the circulation port main body 30.
When fitted to the filter case, the inclined surface 35a guides the inner peripheral surface of the filter case 43, and tightens the circulation port main body 30 in the center direction thereof. That is, by the engagement claw 35,
The engaging projection 36 is pressed toward the center of the circulation port main body 30.

Next, the operation of the bathtub circulator of the present embodiment will be described below. When the bathtub circulator of this embodiment is mounted on a bathtub, first, as shown in FIG. 3, the sleeve 2 is inserted into a mounting hole 25 provided in the side wall 12 of the bathtub.
The sleeve 3 and the rear case 13 are attached by inserting the female screw 3 into the male screw 24 of the sleeve 23 and screwing the female screw portion 22 of the rear case 13.

Next, the pipe connection port 17 of the rear case 13
Is connected to the introduction pipe 18 and the discharge pipe 19 extending from the heater. In the present embodiment, one pipe connection port 17
a and a discharge pipe 19 to the other pipe connection port 17b.

After connecting the pipes 18 and 19 from the heater, the fitting flange 27 of the sleeve 23 is fitted on the back surface of the circulation port main body 30. At this time, the circulation port main body 30 is attached while being positioned so that the pair of openings 39a and 39b face diagonally downward. Subsequently, the filter case 43 is fitted to the circulation port main body 30. At this time, the filters 47a provided in the filter case 43,
47b, one opening 39a serves as a suction port, and a filter 47a having a wire mesh 46 is fitted into the corresponding through-hole 45 as shown in FIG. Also,
Since the other opening 39b functions as a discharge port, a filter 47b having no wire mesh is fitted as shown in FIG.

When the filter case 43 is fitted to the circulation port main body 30, first, the retaining projection 50 of the filter case 43 and the retaining groove 51 of the circulation port main body 30 are aligned, and then the filter case 43 and the circulation The filter case 43 is engaged by engaging the mouth main body 30 and then rotating the filter case 43 by a predetermined angle. At this time, as shown in FIG. 7, the inclined surface 35 a of the engagement claw 35 provided on the circulation port main body 30 is pressed against the inner peripheral surface of the filter case 43 and pressed toward the center of the circulation port main body 30. This prevents the circulation port body 30 from falling off the sleeve 23.

When heating bath water using a heater,
As shown in FIG. 7, the bathtub water is filtered by the wire mesh 46 of the filter 47 a of the filter case 43 while flowing from the through hole 45 and the water passage 44 corresponding to the water passage recess 37 a to the one opening 39 a. Inhaled. Then, as shown in FIG. 3, the bathtub water is sent to the inner chamber 15 of the rear case 13 through the water pipe 31 and the communication pipe 14, and is heated from one pipe connection port 17 a through the introduction pipe 18. It is transferred into the vessel.

The bathtub water heated by the heater flows from the discharge pipe 19 to the other pipe connection port 17 b, and passes through the outer chamber 16 of the rear case 13 and the sleeve 23 to pass the water through the circulation port body 30. It flows into the opening 32. Then, the heated bathtub water is discharged from the other opening 39b that functions as a discharge port through the inside of the circulation port main body 30.

In the circulation of the bathtub water, since the wire net 46 is not attached to the filter 47b on the discharge port side, there is no resistance when the bathtub water is discharged, and the bathtub water stays inside the circulation port body 30. Is prevented. Further, since the size of the water inlet 44 is set so as to correspond to the isolation recess 37, the bath water before heating and the bath water after heating flowing into the water recess 37 are circulated. Mixing in the body 30 is prevented. Further, since the plurality of split grooves 34 are substantially closed by the filter case 43, the bathtub from the back side of the circulation port main body 30, that is, between the circulation port main body 30 and the side wall 12 of the bathtub to the filter case 43 side. Water flow is blocked.

According to the bathtub circulator of the present embodiment having the above configuration, the following effects can be obtained. According to the bathtub circulator of the embodiment, the filter 47
a and 47 b are provided on the inner peripheral wall of the filter case 43. For this reason, the filters 47a and 47b can be prevented from falling off, and the appearance can be improved.

According to the bathtub circulator of the embodiment, the partition wall 38 and the isolation recess 37b are provided as isolation means. For this reason, mixing of the bath water after heating and the bath water before heating in the vicinity of the openings 39a and 39b can be avoided, and a short cycle can be prevented.

According to the bathtub circulating device of the embodiment, the circulation port main body 30 is formed integrally, and the gap that connects the back side and the front side of the circulation port main body 30 is only the split groove 34. I have. This split groove 34 is substantially formed in the filter case 4.
3 closed. For this reason, the circulation port body 30
The bathtub water can be prevented from being discharged or sucked from the back surface of the tub.

According to the bathtub circulator of the embodiment, since the pair of openings 39a and 39b are formed in a cylindrical shape, the resistance in discharging or sucking the bathtub water is reduced, and the flow rate of the bathtub water is reduced. Can be increased.

According to the bathtub circulator of the embodiment, the size of the water inlet 44 of the filter case 43 is configured to correspond to the size of each isolation recess 37b. Mixing of bath water can be avoided, and a short cycle can be effectively prevented.

According to the bathtub circulating device of the embodiment, the filter 47b fitted into the through hole 45 on the side serving as the discharge port.
Since the wire mesh 46 is not attached to the tub, the resistance at the time of discharging the bathtub water can be reduced, and the short cycle can be more effectively prevented.

According to the bathtub circulating device of the embodiment, since the engaging claw 35 is provided with the inclined surface 35a, when the filter case 43 is fitted on the circulation port main body 30, the engaging claw 35 is 43, the sleeve 23 and the circulation port main body 30 are more firmly fitted to each other.
Can easily be prevented from falling off.

According to the bathtub circulating device of the embodiment, the sleeve 23 and the circulation port main body 30 are connected by the engagement relationship between the engagement annular groove 28 and the engagement projection 36. Therefore, the sleeve 23 and the circulation port main body 30 can be easily connected in a short time without using a tool such as a screwdriver.

According to the bathtub circulating device of the embodiment, the positioning ring 33 and the pair of protrusions 26 of the sleeve 23 are oriented in such a manner that the sleeve 23 is attached only by changing the position of the recess 33a to be engaged. Regardless, the circulation port main body 30 can be attached such that the pair of openings 39a and 39b always face obliquely downward.

According to the bathtub circulator of the embodiment, since the seal ring 42 has a T-shaped cross section, when the circulation port body 30 is attached to the sleeve 23, the seal ring 42
The incomplete fitting of the sleeve 23 to the circulation port main body 30 due to the elasticity of the sleeve 23 can be prevented, and the gap between the sleeve 23 and the circulation port main body 30 can be effectively closed.

The present embodiment can be embodied with the following modifications. In the present embodiment, the through hole 45 on the side serving as the discharge port
The filter 47b itself to be fitted into the device is omitted.

With this configuration, the mounting operation can be simplified, and the manufacturing cost can be reduced. In the present embodiment, a pair of openings 39a, 39b
As a triangular cylinder, square cylinder, hexagonal cylinder, etc.

In the present embodiment, the circulation port main body 30 and the sleeve 23 connected by an engagement relationship are connected by a connecting means such as a screw. In the present embodiment, the number of provided isolation recesses 37b is changed, for example, two or more pairs of isolation recesses 37b are provided in upper and lower pairs or three or more pairs. At this time, it is desirable to change the size of the water inlet 44 of the filter case 43 in accordance with the change of the isolation recess.

In this embodiment, the fitting flange 2
An engaging groove 49 is formed on the inner peripheral surface of the back surface of the circulation port main body 30 while an engaging projection 49 is formed so as to protrude on the outer peripheral surface of the circular opening 7.

In the present embodiment, the retaining groove 51 is provided on the inner peripheral surface of the filter case 43, and the retaining protrusion 50 is provided on the outer peripheral surface of the circulation port main body 30.
Further, a technical idea grasped from the present embodiment will be described below.

An engagement protrusion or an engagement groove is provided on the sleeve, and an engagement groove or an engagement protrusion corresponding to the engagement protrusion or the engagement groove is provided on the circulation port main body. The bathtub circulator according to any one of claims 1 to 4, wherein the bathtub circulator is fitted by an engagement relationship.

With this configuration, the sleeve and the circulation port main body can be easily fitted in a short time. The bathtub according to any one of claims 1 to 4, wherein a sealing material made of an elastic material is provided on a contact surface between the sleeve and the circulation port main body, and the sealing material is formed to have a T-shaped cross section. Circulator.

With this configuration, the gap between the sleeve and the circulation port main body can be effectively closed while reducing the resistance to the circulation port main body due to the elasticity of the sealing material.

The bathtub circulating tool according to any one of claims 1 to 4, further comprising a pressing means for fastening the circulating port body to the sleeve when the sleeve and the circulating port body are fitted.

With this configuration, it is possible to more reliably prevent the circulation port main body from falling off the sleeve.

[0060]

As described above in detail, according to the present invention, the following effects can be obtained. According to the bathtub circulating device of the first aspect of the present invention, since the filter is provided on the inner peripheral wall of the filter case, it is possible to prevent the filter from falling off, and to improve the appearance. it can.

According to the bathtub circulator of the second aspect of the present invention, in addition to the effects of the first aspect of the present invention, mixing of discharge water and suction water near the opening can be avoided. , A short cycle can be prevented.

According to the bathtub circulator of the third aspect of the invention, in addition to the effects of the first or second aspect of the invention, bathtub water is discharged or sucked from the back surface of the circulation port body. Can be prevented.

According to the bathtub circulator of the invention described in claim 4, in addition to the effect of the invention described in any one of claims 1 to 3, the opening is formed to have a cylindrical shape. From that, reduce the resistance in the discharge or inhalation of bath water,
The bath water flow can be increased.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a bathtub circulator of an embodiment.

FIG. 2 is an exploded perspective view showing a state in which the bathtub circulating device is viewed from the back side.

FIG. 3 is a sectional view showing a state in which a bathtub circulating device is attached.

FIG. 4 is a sectional view showing a circulation port main body.

FIG. 5 is a sectional view showing a circulation port main body.

FIG. 6 is a sectional view showing a circulation port main body, a sleeve, and a filter case.

FIG. 7 is a sectional view showing a circulation port main body, a sleeve, and a filter case.

FIG. 8 is an exploded perspective view in which a part of the filter is enlarged.

FIG. 9 is a side view showing a circulation port main body, a sleeve, and a filter case.

FIG. 10 is a front view showing a circulation port main body.

[Explanation of symbols]

12 ... side wall of bathtub, 23 ... sleeve, 30 ... circulation port main body, 37b ... isolation recess as isolation means, 38 ... partition wall as isolation means, 39a ... opening serving as suction port, 39
b: opening serving as a discharge port, 43: filter case, 45
... through-hole, 47a ... filter.

Claims (4)

[Claims] 1. A circulation port comprising: a sleeve attached to a side wall of a bathtub; a circulation port main body fitted to the sleeve; and a bottomed cylindrical filter case fitted to the circulation port main body. The main body is connected to an external heater, has a pair of openings functioning as a suction port or a discharge port of bathtub water, and provides a pair of through-holes in a peripheral wall of the filter case corresponding to the pair of openings, A bathtub circulating device in which a filter for preventing foreign matter from entering a through hole corresponding to a suction port of the pair of openings is detachably mounted on an inner peripheral wall of a filter case. 2. The circulating port body between the pair of openings is provided with an isolating means for preventing the bathtub water to be sucked and the bathtub water to be discharged from mixing with each other. Bathtub circulator. 3. The bathtub according to claim 1, wherein bathtub water flowing from between the circulation port main body and the side wall of the bathtub is substantially prevented from flowing to the filter case side. Circulator. 4. The bathtub circulator according to claim 1, wherein the pair of openings are formed to have a substantially cylindrical shape.