JP2007301225A - Liquid container for beverage extracting machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the cost of a beverage container by simplifying the structure of the beverage container capable of securely preventing leakage of a beverage. <P>SOLUTION: The liquid container 25 is disposed under a basket 18 of a beverage extracting machine for extracting the beverage by feeding heated water into the basket 18 in which an extraction material is stored. The liquid container 25 has an inner plug 37 with a beverage reserving path 27 extending from the upper face to the lower face. An extraction port 45 at the lower end of the beverage reserving path 27 in the inner plug 37 comprises a blocking plate 48 which projects to block a part of the beverage reserving path 27; a horizontal opening part 45a formed between the inner peripheral face of the beverage reserving path 27 and the blocking plate 48 when the beverage reserving path 27 is seen from the vertical lower side; and a vertical opening part 45b formed between the lower end of the beverage reserving path 27 and the blocking plate 48 when the beverage reserving path 27 is seen from the horizontal direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a liquid container for a beverage extractor.

  A beverage extractor such as a coffee maker includes a water tank for receiving water and a basket for storing beverage extraction raw materials, and a liquid container for receiving the extracted beverage is detachably installed so as to be positioned below the basket. It is configured. In the beverage extractor, the water tank is connected to a hot water supply pipe that is arranged above the basket, and the hot water pipe is provided with heating means for heating the internal water.

  Prior art document information related to the liquid container for beverage extractors of the present invention includes the following.

JP 2005-192592 A

  This patent document describes a liquid container having a configuration in which a shoulder body is disposed on an upper portion of a container body, and an inner plug is detachably disposed on the shoulder body. A beverage storage passage extending from the upper surface to the lower surface is formed in the inner plug. Further, a beverage dispensing passage is formed between the cylindrical body constituting the beverage storage passage and the inner peripheral surface of the shoulder body. The shoulder body is provided with an extraction passage having a spout at the tip so as to be positioned on the opposite side of the handle, and an air passage is provided so as to be positioned on the handle side.

  Thus, the liquid container in which the inner stopper having the beverage storage passage is disposed is such that the liquid level of the beverage is positioned at the extraction port which is the lower end of the beverage storage passage when the stored beverage is tilted. Then, the beverage leaks out through the beverage storage passage.

  For this reason, in this patent document, a check valve rotatably mounted by an eccentric shaft is provided at the lower end of the beverage storage passage, and is opened by the weight of the beverage when injecting the beverage. The extraction port of the passage is closed.

  However, the inner plug provided with a check valve at the extraction port has a problem that the number of parts is large, the structure is complicated, and the cost is increased. Moreover, when the beverage adhering to the surface of the check valve during injection adheres to the periphery of the extraction port, there is a possibility that the check valve cannot be opened due to the action of surface tension. In this case, there arises a problem that the extracted beverage accumulates in the beverage storage passage and overflows.

  The present invention has been made in view of conventional problems, and provides a liquid container for a beverage extractor that can reliably prevent leakage of an extracted beverage and can reduce costs by simplifying the structure. It is to be an issue.

  In order to solve the above problems, a liquid container for a beverage extractor according to the present invention is disposed in a lower part of the basket in a beverage extractor for extracting a beverage by supplying heated water to a basket containing extraction raw materials, A liquid container provided with an inner stopper having a beverage storage passage extending from an upper surface to a lower surface, wherein an extraction port at a lower end of the beverage storage passage in the inner stopper shields a part of the beverage storage passage. A horizontal opening formed between an inner peripheral surface of the beverage storage passage and the shield plate when the beverage storage passage is viewed from the lower side in the vertical direction, and the beverage storage It has the structure which has the vertical opening part formed between the lower end of this drink storage channel | path and the said shielding board seeing the channel | path for food from the horizontal direction.

  According to the liquid container for a beverage extractor of the present invention, the area of the horizontal opening of the beverage storage passage is reduced by the shielding plate, but since the vertical opening is provided, the opening area of the entire extraction port is sufficient. Can be secured. Therefore, the extracted beverage can be prevented from leaking out and reliably stored in the container body. Moreover, since the opening area of a horizontal opening part is small, the problem which a drink leaks outside through the drink storage channel | path can be suppressed by inclining a liquid container at the time of pouring. In addition, since no separate parts such as a check valve are provided, the structure can be simplified and the cost can be reduced.

  Specifically, the beverage extractor is provided with a stepped portion projecting inwardly on the inner peripheral surface of the container body, and the packing disposed on the outer peripheral portion of the inner plug by tightening the inner plug. In the state where the inner plug packing is in a non-pressure contact pouring position with respect to the container body, the inner plug extraction port is connected to the container body pouring port. On the other hand, it is located on the opposite side. In this way, it is possible to reliably prevent the beverage from leaking outside through the beverage storage passage when the beverage is poured out.

  And in this liquid container, it is preferable to incline the said shielding board downward. If it does in this way, while being able to increase the opening area of a vertical opening part, the fluidity | liquidity of the drink into a container main body can be improved.

  Moreover, it is preferable to provide a concave portion that is recessed upward in a part of the lower end surface of the inner plug so as to be positioned at the lower end of the beverage storage passage, and to project the shielding plate into the concave portion. In this way, when the shielding plate is inclined downward, the shielding plate can be prevented from protruding from the bottom of the inner plug. As a result, when the inner plug is configured to be detachable, stability in a state where it is placed on a sink or the like can be achieved.

  Furthermore, it is preferable to provide a concave portion that is recessed upward on the lower end surface of the inner plug. In this way, when the inner plug is configured to be detachable and placed in a sink or the like, it is possible to prevent the beverage that has adhered to the bottom of the inner plug during dispensing from adhering to the sink.

  In the liquid container for a beverage extractor according to the present invention, the area of the horizontal opening of the beverage storage passage is reduced by the shielding plate, but since the vertical opening is provided, the leakage of the extracted beverage is prevented and reliably Can be stored in the container body. Moreover, since the opening area of a horizontal opening part is small, the problem that a drink leaks outside through the drink storage channel | path at the time of extraction can be suppressed. In addition, since no separate parts such as a check valve are provided, the structure can be simplified and the cost can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 and 2 show a beverage extractor according to an embodiment of the present invention. In this beverage extractor, a liquid container 25 composed of a double container having a high heat retention performance is detachably disposed on an extractor body 10 having a substantially U shape in a side view.

  The extractor body 10 includes a water tank 11 on the back located on the right side in FIG. The water tank 11 is provided so as to extend in the vertical direction, and an upper end thereof is opened to receive water, and the upper end opening is closed by a detachable lid 12.

  Moreover, the base part 13 which arrange | positions the liquid container 25 which receives the drink which flows out from the basket 18 mentioned later so that attachment or detachment is possible is formed in the lower end of the extractor main body 10 so that it may protrude ahead. Furthermore, a nose portion 14 that protrudes forward is formed at the upper end of the extractor body 10 so as to cover the upper portion of the base portion 13. A water supply member 15 for uniformly spraying hot water in the basket 18 is disposed inside the nose portion 14.

  In the upper part of the extractor body 10, a basket housing part 16 having an inner wall 16 a having a substantially semi-cylindrical shape is provided in the lower part of the nose part 14. The basket housing portion 16 is provided with a holder 17 that can be opened and closed in the horizontal direction by a rotating shaft extending in the vertical direction. Inside the holder 17, a basket 18 having a substantially inverted triangular cross section for containing a beverage extraction ingredient is detachably disposed. In addition, the basket housing portion 16 is provided with a liquid container 25 on the base portion 13, thereby opening a water stop valve 19 provided on the basket 18 in contact with the outer surface of the liquid container 25. 20 is arranged to be swingable.

  Inside the extractor main body 10, a metal hot water supply pipe 21 that is continuous with the lower part of the water tank 11 and is bypassed and is provided above the basket 18 is disposed. The base of the hot water supply pipe 21, that is, the detour part at the lower part of the water tank 11, is a supply means for supplying hot water to the upper basket 18 by utilizing the pressure increase caused by heating the water in the hot water supply pipe 21. A heater 22 serving as a role is provided. A temperature sensor 23 composed of a thermostat is disposed in the vicinity of the heater 22.

  In the beverage extractor, when the switch 24 disposed on the surface of the extractor main body 10 shown in FIG. 1 is operated, the heater 22 is always energized at a full power and with a power supply rate of 100%. Then, the water in the lower part of the hot water supply pipe 21 is heated, and when the internal pressure increases due to the temperature rise, the heated hot water is supplied to the basket 18 through the water supply member 15. The hot water supplied to the basket 18 is extracted as a beverage when passing through the extraction raw material in the basket 18 and stored in the liquid container 25. On the other hand, when the water in the hot water supply pipe 21 is completely exhausted, the thermostat as the temperature sensor 23 is turned off due to abnormal temperature rise, and the extraction control is finished.

  On the other hand, as shown in FIG. 2, the liquid container 25 of the present embodiment is detachable by tightening the container body 26, a shoulder body 33 disposed at the upper end of the container body 26, and the shoulder body 33. It consists of the arranged inside plug 37. The inner plug 37 is provided with a beverage storage passage 27 extending from the upper surface (the lid 52) to the lower surface (the bottom of the plug body 38), and between the inner plug 37 and the container body 26, the container body 26 is provided. A beverage dispensing passage 28 for dispensing the beverage stored therein is provided.

  Specifically, the container body 26 has a double structure made of metal (stainless steel) provided with an inner cylinder 29 and an outer cylinder 31 each having a bottomed cylindrical shape. A step portion 30 that protrudes inwardly in an annular shape is provided on the inner peripheral surface of the inner cylinder 29. The outer cylinder 31 is provided with a locking step 32 that is recessed inward so as to form an annular shape in order to lock the shoulder body 33 so as not to be detached.

  The shoulder body 33 is made of resin and has a cylindrical shape that covers from the engaging step portion 32 of the outer cylinder 31 to the inner cylinder 29 and the upper edge of the outer cylinder 31. The shoulder body 33 is provided with a spout 34 that projects outwardly and a handle 35 is provided on the opposite side of the spout 34. In addition, a screw portion 36 for tightening and mounting an inner plug 37 to be described later is provided on the inner peripheral surface of the shoulder body 33.

  The inner plug 37 is positioned below the basket 18 by attaching the liquid container 25 to the base portion 13, and as shown in FIGS. 3A and 3B, a resin plug main body 38. And a lid 52, which are integrated by welding so as not to be detached.

  The plug body 38 has a bottomed cylindrical shape with an upper end opened and a lower end closed. The plug main body 38 is provided with a screw portion 39 that is screwed onto the screw portion 36 on the upper side of the outer peripheral portion, and an annular recess 41 for disposing the packing 40 near the lower end of the outer peripheral portion. When the inner plug 37 is tightened against the shoulder body 33, the packing 40 is pressed against the step portion 30 of the inner cylinder 29 from above, thereby sealing (sealing) the inner periphery of the container body 26. To do. The plug body 38 is provided with a ventilation groove 42 formed of a concave groove deeper than the annular recess 41 so as to bypass the inside of the packing 40.

  In the present embodiment, in order to prevent beverage leakage when the liquid container 25 is tilted so that the spout 34 is positioned on the lower side in a sealed state, the ventilation groove 42 is formed with respect to the spout 34 as shown in FIG. The state positioned on the opposite side in the radial direction is a non-pourable sealed position where the packing 40 is in a pressure contact state, and the state where the ventilation groove 42 is positioned on the spout 34 side is the state where the packing 40 is not pressed. It is set as a non-sealing position that can be poured out. In the stopper main body 38, a concave portion 43 constituting the beverage dispensing passage 28 is provided in the upper part of the ventilation groove 42. Specifically, in the liquid container 25, the beverage dispensing passage 28 communicated with the spout 34 is configured by a space formed between the outer peripheral surface of the inner plug 37 and the inner peripheral surface of the container body 26. . In order to increase the passable area in this state, a recess 43 is formed in the upper portion of the ventilation groove 42 in the plug body 38.

  In addition, a first cylindrical portion 44 constituting the beverage storage passage 27 is provided inside the stopper main body 38 so as to be positioned on the opposite side in the radial direction with respect to the ventilation groove 42. The lower end of the first cylindrical portion 44, which is the lower end of the beverage storage passage 27, serves as an extraction port 45 into the container body 26. Therefore, in the state where the packing 40 of the inner plug 37 is in the non-pressure-contacted extraction position with respect to the container body 26, the extraction port 45 is positioned on the opposite side to the injection port 34 of the container body 26. It is configured.

  Specifically, the lower end of the plug body 38 is provided with a first recess 46 that is recessed upward over substantially the entire surface, and a part of the lower end surface is further upward so as to be positioned at the lower end of the first cylindrical portion 44. A second recess 47 is provided so as to be recessed. As shown in FIG. 3C, the second recess 47 includes a circular recess 47 a that substantially matches the inner diameter of the first cylindrical portion 44, and a rectangular recess 47 b that extends in the opposite radial direction with respect to the ventilation groove 42. A shape having And in this 2nd recessed part 47, the shielding board 48 which protrudes so that a part of extraction port 45 may be shielded is provided in the inside of the circular recessed part 47a. The shield plate 48 allows the extraction port 45 to be positioned between the inner peripheral surface of the first cylindrical portion 44 and the tip edge of the shield plate 48 when viewed from the vertically lower side along the axis of the first cylindrical portion 44. As shown in FIG. 3D, the horizontal opening 45a formed on the bottom surface of the rectangular concave portion 47b, which is the lower end of the first cylindrical portion 44, is shielded when the first cylindrical portion 44 is viewed from the horizontal direction. A structure having a vertical opening 45b formed between the plate 48 and the plate 48 is formed. Therefore, although the area of the horizontal opening 45a is reduced by the shielding plate 48 in the extraction port 45 of the beverage storage passage 27, the entire opening area can be sufficiently secured by the vertical opening 45b. In addition, in this embodiment, the shielding plate 48 is provided so as to be inclined downward, and the opening area of the vertical opening 45b is increased so that the fluidity of the beverage into the container body 26 can be improved. Yes. Further, the shielding plate 48 is provided so as to extend in the opposite direction in the radial direction with respect to the recess 43 constituting the beverage dispensing passage 28, so that the vertical opening 45 b is outside in the radially opposite direction with respect to the recess 43. It is opened to face the direction.

  Note that an annular cutout packing portion 49 is provided on the inner circumferential surface of the upper end of the first cylindrical portion 44. In addition, a rib 51 for restricting the spherical member 50 that suppresses the beverage in the container body 26 from leaking when the liquid container 25 falls is provided at the lower portion of the inner peripheral surface of the first cylindrical portion 44.

  The lid 52 closes the upper end opening of the plug body 38, and is a guide that is recessed downward so that the position corresponding to the first cylindrical portion 44 is the lowest end in the assembled state to the plug body 38. A recess 53 is provided. A second cylindrical portion 54 that is fitted into the first cylindrical portion 44 is provided at the lowermost position of the guide recess 53. The second cylindrical portion 54 includes a large-diameter cylindrical portion 55 that is continuous with the guide concave portion 53, an intermediate-diameter cylindrical portion 56 that is continuous with the large-diameter cylindrical portion 55, and an inverted conical cylindrical portion that is continuous with the intermediate-diameter cylindrical portion 56. 57 and a small-diameter cylindrical portion 58 continuous to the inverted conical cylindrical portion 57. Among them, the step between the large-diameter cylindrical portion 55 and the medium-diameter cylindrical portion 56 serves to position the packing 59 that seals between the first cylindrical portion 44 and the packing disposing portion 49. Further, the lower end opening of the small diameter cylindrical portion 58 has a smaller diameter than the spherical member 50.

  As shown in FIGS. 3A and 3B, in this embodiment, the outer diameters of the medium diameter cylindrical portion 56, the inverted conical cylindrical portion 57 and the small diameter cylindrical portion 58 are made smaller than the inner diameter of the first cylindrical portion 44. By forming a gap of a predetermined interval between them, this gap is set as an area for suppressing the beverage from leaking out from the beverage storage passage 27 during dispensing. That is, when the beverage is stored in the container body 26 through the beverage storage passage 27 formed by the first cylindrical portion 44 and the second cylindrical portion 54, the beverage adheres to the inner peripheral surface of the first cylindrical portion 44 and the spherical member 50. is doing. In this state, when the liquid container 25 is inclined and the beverage is poured out from the spout 34, the beverage adhering in the beverage storage passage 27 may flow backward and leak. However, in this embodiment, since a gap is provided between the first cylindrical portion 44 and the second cylindrical portion 54, the beverage remaining in the interior travels along the inner surface of the first cylindrical portion 44 in the space. Therefore, the second cylindrical portion 54 can be prevented from flowing into the second cylindrical portion 54 from the lower end opening of the second cylindrical portion 54. In addition, on the outer peripheral portion of the upper surface of the lid body 52, a mark 60 that means a pouring position is located at a position that coincides with the ventilation groove 42 and the concave portion 43 in a plan view when assembled to the plug body 38. Is provided.

  When the beverage is extracted from the basket 18 onto the guide recess 53, the liquid container 25 for the beverage extractor is guided to the beverage storage passage 27 including the first cylindrical portion 44 and the second cylindrical portion 54. Then, the beverage flows down the beverage storage passage 27 extending in the vertical direction, and most of the beverage collides with the shielding plate 48 and flows out from the vertical opening 45 b of the extraction port 45 into the container body 26. At this time, the air in the container body 26 is exhausted from the spout 34 through the ventilation groove 42 located on the opposite side in the radial direction from the extraction port 45 and the gap between the inner plug 37, the container body 26 and the shoulder body 33. . Therefore, a reliable ventilation function can be obtained, and the air can be stored efficiently without the air inside the container body 26 flowing backward from the beverage storage passage 27 and preventing the storage action. Further, the extraction port 45 of the beverage storage passage 27 has the horizontal opening 45a made smaller by the shielding plate 48, but since the vertical opening 45b is provided, the opening area of the entire extraction port 45 is sufficiently large. It is secured. Therefore, the extracted beverage can be prevented from leaking and reliably stored in the container body 26.

  When the stored beverage is to be poured out, the liquid container 25 is taken out from the extractor body 10 by holding the handle 35, and the inner plug 37 is placed on the shoulder 33 so that the mark 60 is located at the spout 34. After rotation, the beverage is poured into a desired container by inclining so that the spout 34 is located on the lower side. At this time, the beverage in the container main body 26 is poured from between the outer periphery of the inner plug 37 and the inner surface of the container main body 26 because the pressure contact between the packing 40 and the stepped portion 30 is released by loosening the inner plug 37. It flows into the mouth 34 and is poured out. In addition, in this state, since the concave portion 43 is located below the spout 34, the beverage can easily accumulate in the concave portion 43, and the amount dispensed can be secured, so that the workability can be improved. On the other hand, since the extraction port 45 of the beverage storage passage 27 is located on the opposite side in the radial direction with respect to the recess 43, it is located at the uppermost position inside the container body 26, and the horizontal opening 45 a is formed by the shielding plate 48. The opening area is reduced. Moreover, the vertical opening 45 b is opened so as to face outward in the opposite radial direction with respect to the recess 43. Therefore, it is possible to reliably prevent the beverage from flowing back and leaking through the beverage storage passage 27 from the extraction port 45 at the time of pouring, and also acts as an air passage.

  In the state of FIG. 2 in which the packing 40 is pressed so as not to be dispensed without rotating the inner plug 37 so as to loosen, it communicates from the spout 34 to the inside of the container body 26 only through the ventilation groove 42. ing. However, in this state, since the ventilation groove 42 is positioned on the opposite side in the radial direction with respect to the spout 34, when the spout 34 is inclined so as to be positioned on the lower side, the ventilation groove 42 42 is located at the uppermost position inside the container body 26. Therefore, it is possible to prevent the beverage from being dispensed in a misused state. Incidentally, in this state, the extraction port 45 of the beverage storage passage 27 is located on the spout 34 side. However, the beverage does not leak from the beverage storage passage 27 extending in the vertical direction. Of course, even if the liquid container 25 falls in this state, leakage from the beverage storage passage 27 can be suppressed by the spherical member 50, and leakage from the ventilation groove 42 can be suppressed to the maximum.

  As described above, the liquid container 25 of the present invention has a simple configuration in which the packing 40 is disposed on the outer peripheral portion of the inner plug 37 and the ventilation groove 42 is provided on a part of the outer peripheral portion so as to bypass the packing 40. Therefore, the cost can be reduced. In addition, since the beverage storage passage 27 can reliably prevent the backflow without providing other parts such as a check valve, the structure can be simplified and the cost can be further reduced.

  On the other hand, when the liquid container 25 is washed, the inner plug 37 is rotated in a loosening direction and removed from the shoulder body 33. In this state, the inside of the container body 26 to which the shoulder body 33 is fixed is washed, and the outer peripheral surface of the inner plug 37 is washed. At this time, the inner plug 37 is provided with a first recess 46 on the bottom surface and a second recess 47 at the position where the beverage storage passage 27 is formed. Therefore, when this inner plug 37 is placed in a sink or the like, it is possible to prevent the beverage that has adhered to the bottom of the inner plug 37 during pouring from adhering to the sink. In addition, since these structures can prevent that this shielding board 48 contact | abuts to a sink, when providing the shielding board 48 which inclines in the extraction port 45 of the drink storage channel | path 27 like this embodiment, it is more effective. Is.

  In addition, in this embodiment, since the ventilation groove 42 is provided so as to bypass the inside of the packing 40, a thin linear member is inserted into the ventilation groove 42 and the packing 40 is deformed outward from the inside. The packing 40 can be easily removed. Therefore, it is very hygienic for storing beverages such as coffee, in which bacteria are easier to propagate than water. Incidentally, when the beverage is poured, the beverage easily enters the ventilation groove 42 and remains due to surface tension. However, since the packing 40 is slightly deformed by repeatedly pressing and releasing the pressure to the stepped portion 30, it is possible to remove the residual liquid.

  In addition, the liquid container 25 for drink extractors of this invention is not limited to the structure of the said embodiment, A various change is possible.

  For example, in the above-described embodiment, the container body 26 is constituted by a metal double container, but may be a vacuum double container, a single-layer glass container, a single-layer resin container, or the like.

It is a side view which shows the drink extractor equipped with the liquid container of this invention. It is sectional drawing of FIG. Fig. 2 shows a middle stopper of a liquid container, (A) is a cross-sectional perspective view, (B) is a cross-sectional view, (C) is a bottom view of the main part of the beverage storage passage viewed from the vertical direction, and (D) is a beverage storage passage. It is principal part sectional drawing which looked at from the horizontal direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Extractor main body 18 ... Basket 25 ... Liquid container 26 ... Container main body 27 ... Beverage storage passage 28 ... Beverage extraction passage 30 ... Step part 33 ... Shoulder body 34 ... Spout 37 ... Inner plug 38 ... Plug main body 40 ... packing 42 ... ventilation groove 43 ... recess 44 ... first cylindrical part 45 ... extraction port 45a ... horizontal opening 45b ... vertical opening 46 ... first recess 47 ... second recess 48 ... shielding plate 52 ... lid 54 ... first 2 cylindrical parts

Claims (5)

In a beverage extractor for extracting a beverage by supplying heated water to a basket containing an extraction raw material, a liquid provided with an inner stopper having a beverage storage passage disposed at a lower portion of the basket and extending from an upper surface to a lower surface A container,
The extraction port at the lower end of the beverage storage passage in the inner plug includes a shielding plate protruding so as to shield a part of the beverage storage passage, and the beverage storage passage is viewed from the lower side in the vertical direction. A horizontal opening formed between the inner peripheral surface of the beverage storage passage and the shielding plate, and between the lower end of the beverage storage passage and the shielding plate when the beverage storage passage is viewed from the horizontal direction. A liquid container for a beverage extractor, characterized by having a vertical opening formed.   A step portion projecting inwardly is provided on the inner peripheral surface of the container main body, and the packing provided on the outer peripheral portion of the inner plug is pressed and sealed to the step portion from above by tightening the inner plug. The extraction port of the inner plug is positioned on the opposite side to the injection port of the container body in a state where the packing of the inner plug is in a non-pressure-contacted extraction position with respect to the container body. The liquid container for beverage extractors according to claim 1.   The liquid container for a beverage extractor according to claim 1 or 2, wherein the shielding plate is inclined downward.   The recessed part which dents upwards is provided in a part of lower end surface of the inner plug so as to be positioned at the lower end of the beverage storage passage, and the shielding plate projects in the recessed part. The liquid container for beverage extractors according to any one of claims 3 to 3.   The liquid container for a beverage extractor according to any one of claims 1 to 4, wherein a concave portion that is recessed upward is provided in a lower end surface of the inner stopper.

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