JPH039721Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(Field of Industrial Application) The present invention relates to an improvement in a bubble bathtub that produces a pine surge effect by ejecting a stream of bubbles toward a bather. (Prior Art) Bubble bathtubs have been known for a long time. As disclosed in Japanese Utility Model Publication No. 62-14864, a bubble bathtub is constructed by connecting a bubble jetting device provided in a bathtub body and a water intake port through a circulation path equipped with a circulation pump. The circulation pump operates to send the bathtub water sucked in from the water inlet to the bubble jetting device, which jets out the bubbles. As shown in FIG. 19, the bubble jetting device 2'
An injection nozzle 23 communicating with the water intake port via a circulation path
The mixing nozzle 22' is arranged in front of the mixing nozzle 22'. The mixing nozzle 22' has an air supply port 2 at the rear end of a flow path 22c formed in a throat portion formed in a cylindrical shape.
A mixing chamber 22a' that communicates with 1d' is integrally formed, and the tip of an injection nozzle 23 is inserted into the mixing chamber 22a'. And this mixing nozzle 22
In a', air is mixed into the circulating water (jet flow) jetted from the jet nozzle 23 by the suction effect of the jet pressure, and a bubble flow is jetted from the flow path 22c. The circulation path is constructed by connecting a bubble jetting device 2' integrally attached to the tank wall 1b and a water intake port with a communication pipe 6 equipped with a circulation pump installed directly on the installation floor. (Problem to be solved by the invention) According to the above-described bubble flow jetting device 2', the flow rate of the circulating water is rapidly increased by the jet nozzle 23, and air is forcibly mixed into the circulating water. Since a bubble flow is obtained, turbulence is likely to occur on the surface of the circulating water (spout flow) flowing in the flow path 22c, and when this turbulence collides with the bath water in the bathtub, an impact sound is generated. There was a risk that the tank wall 1b would resonate due to the impact sound and cause noise. Further, according to the above circulation path, the bathtub body and the circulation pump are integrally connected via the communication pipe 6, and the communication pipe 6 further presses the circulation pump against the installation floor surface. Therefore, the vibrations generated when the circulation pump is in operation are transmitted to the tank wall 1b through the communication pipe 6, and there is a risk that the tank wall 1b will resonate and further increase the above-mentioned noise. At the same time, there was a risk that the vibrations of the pump would be transmitted to the floor surface on which the pump is installed, causing resonance on the floor surface and inducing noise. The above-mentioned noise is noticeable when the bathtub is made of FRP, or when the bathroom is constructed from a unit bathroom made of PVC steel panels, which not only causes discomfort to bathers, but also causes noise from neighboring rooms and floors. There was a risk that the air could spread to the upper and lower floors, which was an obstacle when installing bubble bathtubs in apartment complexes. The present invention was developed in view of the conventional circumstances described above, and its first purpose is to extremely easily reduce the impact noise that occurs when circulating water jetted from a jet nozzle collides with bath water. To provide a bubble bathtub which is free from the possibility of generating noise by suppressing the vibrations of the circulation pump with a structure and at the same time absorbing the vibrations of the circulation pump between the bathtub body and the installation floor. A second object of the present invention is to make it possible to easily replace the means for suppressing the impact noise, and to minimize the possibility that the ejection pressure of the bubble flow will decrease due to the provision of this means. The goal is to keep it to a minimum. (Means for Solving the Problem) In order to achieve the above object, the first means of the present invention is to provide the throat portion with a desired length along the spouting direction of the circulating water, and to extend the length from the center of the throat portion. A flow regulating plate consisting of a plurality of rectifying plates extending substantially radially toward the inner circumferential surface is detachably attached, and an end of each of the rectifying plates on the mixing chamber side is inclined from the center of the throat portion toward the inner circumferential surface. Further, a vibration isolating part is provided in the middle of the connecting pipe to absorb the vibration of the circulation pump transmitted to the connecting pipe, and a vibration isolating part is provided between the circulation pump and the floor where the circulation pump is installed, and the vibration isolating part is provided between the circulation pump and the floor where the circulation pump is installed. It is characterized by the provision of a vibration isolating material that absorbs vibrations. A second means of the present invention is characterized in that the end of each rectifying plate on the side of the mixing chamber is formed into an edge shape with an acute angle in cross section, instead of the inclined surface of the first means. Furthermore, a third means of the present invention is characterized in that the inclined surface of the first means is formed into an edge shape with an acute angle in cross section. (Function) The function of the first means is as follows.・The circulating water that is ejected from the injection nozzle and mixed with air in the mixing chamber is divided into several divided streams by a plurality of rectifying plates that extend approximately radially from the center of the throat toward the inner peripheral surface, and the circulating water is By adjusting the ejection direction of each branched flow by the respective rectifier plates provided at a desired length along the ejection direction of the flow, the circulation is passed through the throat portion while being rectified to a state as close to laminar flow as possible. Minimize turbulence on the water (jet) surface as much as possible. Thereby, the impact sound when the circulating water (spout flow) collides with the bathtub water is made as small as possible, and resonance of the bath wall is prevented. - The vibration of the circulation pump transmitted to the connecting pipe is absorbed by the vibration isolating part to prevent resonance of the tank wall due to the vibration being transmitted to the bathtub body. - The vibration isolator adds elasticity to the connecting pipe to reduce the force pressing the circulation pump against the installation floor, and the vibration isolator absorbs the vibrations of the circulation pump and transmits them to the installation floor. This prevents the resonance of the installation floor surface and reduces the vibration noise of the circulation pump. - The inclined surface reduces the pressure resistance when the circulating water (jet flow) collides with the end of the fluid regulator on the side of the mixing chamber. - By providing a removable fluid regulator, the fluid regulator can be easily replaced. Further, according to the second means of the present invention, the edge portion of each straightening plate formed in an edge shape on the side of the mixing chamber functions in the same manner as the above-mentioned inclined surface, and is substantially equivalent to the first means. obtain the effect of Furthermore, according to the third means of the present invention, in addition to the effect of the first means described above, the inclined surface is made into an edge shape, so that the circulating water (jet flow) is directed to the end of the regulating fluid on the side of the mixing chamber. This further reduces the pressure resistance when colliding with the (Example) Examples of the present invention will be described below based on the drawings. First, the embodiment shown in FIGS. 1 to 3 will be described. A in the figure shows a bubble bathtub of the present invention, which is equipped with a bathtub body 1 integrally molded from FRP or the like, and a bubble flow jetting device 2 provided on the bathtub body 1 and a water intake port 3 are connected through a circulation path 4. There is. The circulation path 4 is configured by connecting the bubble flow jetting device 2 and the water intake port 3 through a communication pipe 6 equipped with a circulation pump 5. The communication pipe 6 is connected between the other end of the metal fitting side pipe 6a whose one end is connected to the bubble jetting device 2 or the water inlet 3, and the other end of the pump side pipe 6b whose one end is connected to the circulation pump 5. A vibration isolating portion 6c is formed by connecting the other ends with a rubber tube 6c'. The rubber tube 6c' has the desired elasticity and absorbs the vibration of the circulation pump 5 transmitted to the pump side pipe 6b.
This vibration is not transmitted to the pipe 6a on the metal fitting side. The circulation pump 5 sucks bathtub water 1a in the bathtub from the water intake port 3 and sends it to the bubble flow jetting device 2.
This jet device 2 has a sufficient function to jet a bubble flow into the bathtub body 1. Further, a waterproof cover 7 is provided around the circulation pump 5,
Further, a vibration isolating material 8 is provided between the installation floor surface B and the installation floor surface B. The installation floor surface B is formed by, for example, a room floor surface constituting a unit bathroom. The waterproof cover 7 is a sound-absorbing board with sound-absorbing material pasted on the inner surface.
Alternatively, it is formed of a vibration damping plate having unevenness on its surface, and covers the circumference of the circulation pump 5.
This prevents the circulation pump 5 from malfunctioning due to adhesion of water droplets, etc., and reduces vibration noise when the circulation pump 5 is in operation. The vibration isolator 8 is a vibration isolator fitted to the lower end of the leg 7a protruding from the lower surface of the waterproof cover 7, and absorbs the vibration of the circulation pump 5 so as not to transmit it to the installation floor B. The bubble flow jetting device 2 has a recess 21c, a front chamber 21d, and a front chamber 21d extending from the front opening 21a to the bottom wall 21b.
A bottomed cylindrical body portion 21 having a continuous rear chamber 21e, and a mixing nozzle 2 installed in the recess 21c.
2. Injection nozzle 2 located behind the mixing nozzle 22
3, and is attached to a mounting hole 1c drilled in the tank wall 1b. The mixing nozzle 22 includes a spherical part 22a rotatably accommodated in a mounting step 21c' stepped at the rear end of the recess 21c, and a front opening 2 from the spherical part 22a.
It is integrally formed with a cylindrical throat portion 22b that protrudes toward 1a, so that the protrusion angle of the throat portion 22b into the bathtub can be adjusted as desired. The spherical part 22a is provided with a mixing chamber 22a' that expands toward the injection nozzle 23 inside thereof, and an annular rubber gasket 24 provided in the mounting step part 21c'.
It is held in place. The throat portion 22b has a mixing chamber 22 inside thereof.
a', a locking part 22d is provided at the tip of this channel 22c, and a groove 22e is provided around the rear end of the channel 22c.
A rectifier 25 is installed inside c. The flow regulating plate 25 includes a cylindrical outer frame portion 25a that can be inserted into the flow path 22c, and a plurality of flow regulating plates 25b that radiate in a cross-shaped cross section from the center of the flow path 22c to the peripheral wall of the outer frame portion 25a. A projecting piece 25c is formed on the outer periphery of the outer frame portion 25a to detachably engage with the groove 22e by a spring action. In this way, the flow path 22c is divided into a plurality of divided flow paths 25d along the jetting direction of the bubble flow by the plurality of rectifying plates 25b. Furthermore, an inclined surface 26 that is inclined from the center of the outer frame portion 25a toward the peripheral wall is provided at the end of each rectifier plate 25b on the upstream side of the flow path 22c. The inclined surface 26 is inclined at an acute angle from the center of the outer frame toward the downstream side of the flow path 22c. moreover,
The inclined surface 26 has an edge 26a having an acute angle in cross section.
has been formed. The main body part 21 has a front opening 21a projected into the bathtub main body 1 by inserting its tip portion into the attachment hole 1c from the outside of the tank wall 1b, and has a nut 27 screwed onto the outer periphery of the front opening 21a, and a nut 27 provided around the outer periphery. The tank wall 1b is held between the flange portion 28 and the tank wall 1b is attached to the attachment hole 1c. Further, the rubber packing 24 is fitted into the mounting stepped portion 21c', and the rubber packing 24 is supported by the presser plate 29 and the decorative cover 9 so as not to fall off. Furthermore, an air supply port 21d' that communicates with the front chamber 21d and a communication port 21e' that communicates with the rear chamber 21e are provided on the peripheral wall, and the air supply port 21d' is provided with an air supply path that communicates with an air supply device (not shown). 10 and the metal pipe 6a of the connecting pipe 6 are connected to the communication port 21e'. The decorative cover 9 is formed of a cylindrical body part 91 that is screwed into the inner periphery of the recess 21c, and a cover part 92 that is provided around the outer periphery of the distal end of the cylindrical body part 91 and covers the distal end of the main body part 21. The injection nozzle 23 is connected to the rear chamber 21 by the circulation path 4.
The tip is formed into a substantially conical shape with a small diameter so that the circulating water supplied into the mixing chamber 22a' can be vigorously jetted toward the mixing chamber 22a'. And the rear chamber 21e
It protrudes from the front opening 21a toward the front opening 21a, with its tip facing into the mixing chamber 22a'. The operation of this embodiment will be explained below.
By absorbing the vibration of the circulation pump 5 transmitted to the pump-side pipe 6b by c, this vibration can be prevented from being transmitted to the tank wall 1b, and resonance of the tank wall 1b can be prevented. Furthermore, the vibration isolating portion 6c imparts elasticity to the communication pipe 6, thereby reducing the force pressing the circulation pump 5 against the installation floor surface B. At the same time, vibration of the circulation pump 5 is absorbed by the vibration isolating material 8 to prevent transmission of this vibration to the installation floor surface B, thereby preventing resonance of the installation floor surface B and reducing vibration noise of the circulation pump 5. Further, the circulation pump 5 jets the bathtub water sucked in from the water intake port 3 toward the mixing chamber 22a' through the jet nozzle 22. Then, the air supplied from the air supply port 21d' is mixed with the circulating water (the jet stream) in the mixing chamber 22a' due to the suction effect of the jet pressure, thereby generating a bubble flow. At this time, the circulating water (spouting flow) is divided into several branch streams by a plurality of rectifying plates 25b extending approximately radially, and the jetting direction of each branch stream can be adjusted by each rectifying plate 25b. By passing through the flow path 22c while rectifying the flow to a state close to laminar flow, the occurrence of turbulence on the surface of the circulating water (spouting flow) is minimized, and the circulating water (spouting flow) is made to flow in the bathtub. To reduce the impact sound when colliding with 1a as much as possible. At the same time, the slope 26 and the edge 26
Due to the synergistic effect of a, the pressure resistance when the circulating water (jet flow) collides with the end of each rectifying plate 25b on the mixing chamber 22a' side is reduced, and the circulating water (jet flow) is rectified. To reliably reduce the drop in the ejection pressure of bubble flow. Furthermore, at that time, the packing 24 is connected to the mixing nozzle 2.
2, and prevents the vibration from being transmitted to the tank wall 1b. In addition, the fluid regulator 25 has a distal end portion and a locking portion 22.
d and the engagement between the protruding piece 25c and the groove 22e, it is immovably supported within the flow path 22c. Further, in the event of breakage, etc., the protruding piece 25c and the groove 22e are disengaged and taken out from the inside of the flow path 22c. The order of taking out the fluid regulator 25 will be explained below. First, the decorative cover 9 is rotated and removed from the recess 21c, and then the presser plate 29 is taken out and the mixing nozzle 2 is removed.
2 and packing 24 from the mounting step 21c'.
Then, use a tool such as a screwdriver to remove the protruding piece 25c.
The groove 22e is disengaged from the groove 22e, and the fluid regulator 25 is taken out from the mixing chamber 22a' side. In this embodiment, since the spherical part 22a is held between the rubber packing 24, the case where the spherical part 22a is held between the rubber packing 24 and the synthetic resin receiver 24a as in the conventional product shown in FIG. Compared to this, it is possible to absorb the vibration of the mixing nozzle 22 and prevent resonance of the tank wall 1b due to this vibration. Note that the vibration isolating portion 6c is not limited to the structure described above, and may include a bent portion 6d in place of the rubber tube 6c' in the middle of the synthetic resin connecting tube 6 as shown in FIG. 4 or FIG. Alternatively, it is also possible to form a curved portion 6e, or to provide a bellows portion 6f in the middle of a metal communication pipe 6 as shown in FIG. In this case, the bent portion 6d, the curved portion 6e, and the bellows portion 6f act in the same manner as the rubber tube 6c' and function as the vibration isolating portion 6c. Further, the vibration isolating material 8 may be provided in the middle of the leg portion 5a protruding from the lower surface of the circulation pump 5, as shown in FIG. In this case, the vibration isolating material 8 can prevent not only the installation floor B but also the resonance of the waterproof cover 7, thereby further suppressing the generation of noise when the circulation pump 5 is in operation. Further, the means for engaging the flow regulating plate 25 and the throat portion 22b for attaching the regulating plate 25b into the flow path 22c is not limited to that shown in FIGS. 1 and 3,
Screws 30a, 30b as shown in FIG. 7 or 8
A snap ring 30c is removably fitted into a groove 22e as shown in FIG. 9, and a convex portion 30d as shown in FIGS. 10 and 11.
It is also possible to fit the recess 30e into the recess 30e. Further, the cross-sectional shape of the flow regulator 25 is a cross shape with the outer end as the free end as shown in FIG. 12, a cross shape with the inner end as the free end as shown in FIG. 13, and a cross shape as shown in FIG. A partition piece 25 that partitions the inside of each divided flow path 25d.
It is also possible to have a cross-shape with d' or a desired cross-sectional shape radiating from the center of the outer frame portion 25a to the peripheral wall as shown in FIGS. 15 to 17. In this case, a rectifying fluid 25, as shown in FIGS. 12, 13, and 15, is used, which reduces the contact area between each of the rectifier plates 25b and the circulating water (jet flow) to increase the ejection pressure of the bubble flow. Alternatively, prepare in advance a rectifier 25 with a weak jetting pressure of bubble flow by increasing the contact area between each rectifier plate 25b and the circulating water (jet flow) as shown in FIGS. 14 and 16, and By arbitrarily exchanging the fluid 25, it is possible to obtain a bubble flow with an appropriate ejection pressure according to the user's preference. Furthermore, in this case, if the engaging means shown in FIG. 7 is used, the fluid regulator 25 can be replaced extremely easily without removing the mixing nozzle 22 from the main body 21. Furthermore, the inclined shape of the inclined surface 26 is not limited to that shown in FIG. 1, but may include a bent shape as shown in FIG. 7, a curved shape as shown in FIG. 8, and a flow path as shown in FIG. It is also possible to have a shape that slopes toward the upstream side of 22c. Furthermore, each rectifier plate 25b is
A structure in which the slope 26 is not provided with an edge 26a as shown in FIGS. 7 to 9, or a structure in which an edge 26a is not provided on the slope 26 as shown in FIG.
It is also possible to form a structure in which an edge 26a is provided over the entire length of the upstream end. Next, the embodiment shown in FIG. 18 will be described. In this embodiment, the mixing nozzle 22 in the embodiment described above is provided in the main body 21 in a non-rotatable manner. The mixing nozzle 22 has a mixing chamber 22a' at the rear end of the throat part 22b, and a threaded part 22 on the outer periphery.
b' is carved, and this threaded part 22b' is inserted into the recessed part 21.
c It is screwed into the rear end and installed inside the main body part 21. The bubble jet device 2 in this embodiment is used in a case where the amount of protrusion of its tip portion into the bathtub body is limited, that is, if the bubble jet device 2 is not provided with a concave portion (not shown) for mounting the bubble jet device 2. Used when converting a bathtub into a bubble bathtub. Below, the bubble bathtub A of the present invention shown in FIG. 1,
A conventional bubble bathtub equipped with a bubble flow jetting device shown in FIG.
Table (1) shows the measurement results of the noise and ejection pressure when the bubble flow is ejected in A'), and the measurement results of the vibration level of the bathtub body 1 and installation floor B and the vibration sound of the circulation pump 5 when the bubble flow is ejected. The results are shown in Table (2). In Table (1), the noise was measured at a position 1.2 m above the floor, 1 m from the center of the bathtub body 1, and the jet pressure was measured at a position 1 cm away from the tip of the mixing nozzle 22 in the bubble jet device 2. Ivy. Furthermore, in Table (2), the vibration noise of the circulation pump was measured at a position 30 cm away from the center of the pump.

【table】

[Table] As a result, it was found that according to the bubble bathtub A of the present invention, the noise was reduced by 4 dB compared to the conventional bubble bathtub A', and the ejection pressure of the bubble flow was approximately the same pressure. Therefore, it has been confirmed that the energy of the noise when the bubble flow is ejected is reduced to about 1/2, and that the decrease in the ejection pressure of the bubble flow due to the provision of the flow regulator 25 in the flow path 22c can be minimized as much as possible. did it. Moreover, according to the bubble bathtub A of the present invention, compared to the conventional bubble bathtub A', the bathtub body 1 and the installation floor surface B
It was confirmed that the resonance noise of the bathtub body 1 and the installation floor B, and the vibration noise of the circulation pump 5 could be reduced by suppressing the vibrations of the bathtub body 1 and the installation floor B. In addition, the bubble bathtub A of the present invention in the above measurement results
are not limited to those shown in FIG. 1, but include the vibration isolating part 6c shown in FIGS. 4 to 6, the vibration isolating material 8 shown in FIG. 4, the mixing nozzle 22 shown in FIGS. 7 to 10,
Regulator 25 and 18 shown in FIGS. 12 to 17
It was confirmed through experiments that even when the bubble jetting device 2 shown in the figure was used, numerical values similar to or similar to the results described above could be obtained. (Effects of the invention) Since the present invention is constructed as described above, it produces the effects described below. According to the bubble bathtub according to claim 1 or 2, air bubbles are prevented by the fluid regulation provided in the throat portion, the vibration isolating portion provided in the middle of the connecting pipe, and the vibration isolating material provided on the circulation pump installation surface. Resonance between the tank wall and pump installation surface during jetting and vibration noise of the circulation pump can be minimized as much as possible. Therefore, even if the bathtub body is molded from FRP or used for a unit bathroom, there is no risk of the tank wall or room floor (the floor where the circulation pump is installed) resonating and generating noise, making it easy to use while bathing. To provide a bubble bathtub with an extremely simple structure, which is not only free from the risk of causing discomfort to persons, but also is ideal for installation in an apartment complex. In addition, the slope or edge makes it possible to minimize the drop in the ejection pressure of the bubble flow due to the provision of a flow regulator, thereby preventing a reduction in the pine surge effect caused by rectifying the bubble flow. I can do it. In addition, if the current plate is damaged due to long-term use, it is only necessary to replace the current flow regulator without replacing the entire bubble flow jetting device. It is possible to eliminate wasteful costs incurred when replacing the flow regulator. Furthermore, by preparing several types of fluid regulators with small or large contact areas with the circulating water (spouting flow) in advance, and installing any fluid regulator in the throat part, it is possible to adjust the appropriate spray pressure according to the bather's preference. It also becomes possible to obtain a bubble flow. Further, according to the bubble bathtub according to claim 3, in addition to the above-mentioned effects, due to the synergistic effect of the slope and the edge, it is possible to more effectively prevent the drop in the ejection pressure of the bubble flow due to the provision of the flow regulator. Therefore, reduction in the pine surge effect due to rectification of the bubble flow can be more reliably prevented.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view of the bubble bathtub of the present invention, showing the main parts on an enlarged scale. FIG. 2 is a sectional view taken along line 2-2 in FIG. 1, FIG. 3 is an enlarged perspective view of the mixing nozzle, and FIG. 4 is a sectional view of the vibration isolating part and vibration isolating material in another embodiment.
5 and 6 are side views of the vibration isolating part in still another embodiment, and FIGS. 7 to 10 are vertical sectional side views showing modified examples of the mixing nozzle and the flow regulator, respectively.
1 is a sectional view taken along the line 11-11 in FIG. 10, FIGS. 12 to 17 are vertical left side views of a flow regulating plate showing modified examples of the current regulating plate, and FIG. 18 is a bubble flow jetting device in another embodiment. FIG. 19 is a vertical side view of a bubble jet device in a conventional bubble bathtub. In addition, in the figure, 1...Bathtub body, 2...Bubble jet device, 3...Water inlet, 5...Circulation pump, 6...
Communication pipe, 23... Injection nozzle, 22... Mixing nozzle, 22b... Throat part, 21d'... Air supply port,
22a'...mixing chamber, 25b...straightening plate, 25...
Flow regulator, 6c...Vibration isolation section, B...Installation floor, 8...
...Vibration isolating material, 22c...Gouting channel, 26...Slope, 26a...Edge.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A bubble jetting device provided in the bathtub body and a water intake port are connected by a connecting pipe equipped with a circulation pump,
The bubble flow jetting device includes a jetting nozzle that jets circulating water into the bathtub, and a mixing nozzle that is located in front of the jetting nozzle and mixes air into the circulating water jetted from the jetting nozzle, and The mixing nozzle is configured by integrally providing a mixing chamber communicating with the air supply port at the base end of a throat portion formed in a cylindrical shape, and inserting the tip of the injection nozzle into the mixing chamber to cause the air to be ejected from the injection nozzle. In the bubble bath, air is mixed into the mixing chamber by the suction effect of the ejecting pressure of the circulating water.
A fluid rectifier consisting of a plurality of rectifying plates having a desired length along the spouting direction of the circulating water and extending substantially radially from the center of the throat portion toward the inner circumferential surface is detachably attached, and the mixing chamber of each of the rectifying plates is removably attached. The side end is a sloped surface that slopes from the center of the throat part toward the inner circumferential surface, and a vibration isolating part is provided in the middle of the connecting pipe to absorb vibrations of the circulation pump transmitted to the connecting pipe. A bubble bathtub characterized in that a vibration isolating material is provided between the pump and the floor surface on which the pump is installed to absorb vibrations of the circulation pump transmitted to the floor surface. (2) The bubble bathtub according to claim 1, characterized in that, in place of the inclined surface, the end of each rectifier plate on the side of the mixing chamber is formed into an edge shape with an acute angle in cross section. (3) The bubble bathtub according to claim 1, wherein the inclined surface is formed into an edge shape with an acute angle in cross section.