Pressure accumulator type discharger

Abstract

To suppress the deformation of a sub-piston which is deformed so that it adheres to the inner surface of a lower cylinder when a push head is pushed down, even with the content to be discharged containing oil components.SOLUTION: A sub-piston 72 of a plunger body, which protrudes upward from inside a main cylinder and is supported so as to be movable downward in an upwardly biased state, includes: an upper seal cylinder part 13 extending toward the outer side in the radial direction as it extends from the bottom to the top; a lower seal cylinder part 14 extending toward the outer side in the radial direction as it extends downward from the upper side; and a plurality of longitudinal ribs 15 provided at circumferential intervals and connecting in the vertical direction the outer circumferential surface of the portion of the upper seal cylinder part located downwardly from an upper end part 13a and the outer circumferential surface of the portion of a lower seal cylinder part located upwardly from a lower end part 14a. The longitudinal ribs are located radially inward of the upper end part of the upper seal cylinder part and the lower end part of the lower seal cylinder part.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a pressure accumulator type dispenser.

Background Art

[0002] For example, as shown in Patent Document 1 below, a main cylinder extending in the vertical direction and having an inner side communicating with the inside of the container body, a plunger body protruding upward from the inside of the main cylinder and supported so as to be movable downward in an upwardly biased state, and an upper part provided above the plunger body. A pressing head having a discharge hole through which the content is discharged, an upper cylinder to which the pressing head is attached, and a lower cylinder in which the upper end portion of the plunger body is accommodated so as to be movable downward inside, and an upper cylinder and a lower cylinder are vertically connected. And a sub-cylinder in which a communication hole is formed, and the plunger body includes a main piston fitted movably downward in the main cylinder, a sub-piston fitted movably downward in the lower cylinder, and an upper valve body that closes the communication hole from the lower side of the communication hole. And a communication path that communicates a pressure accumulation space partitioned by the sub-piston and having the communication hole opened in the lower cylinder with the inside of the main cylinder. A pressure accumulator type dispenser is known.

[0003] In this pressure accumulator type dispenser, when the pressing head is pushed down, the sub-cylinder and the plunger body descend with respect to the main cylinder, so that the inside of the main cylinder is pressurized, and the content inside the main cylinder flows into the pressure accumulation space through the communication path. Then, when the internal pressure of the pressure accumulation space reaches a predetermined value, the plunger body descends with respect to the sub-cylinder. As a result, the upper valve body opens the communication hole, and the pressure accumulation space and the discharge hole communicate with each other through the communication hole. As a result, the content is discharged to the outside through the discharge hole.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in the accumulator type discharger described above, if the discharged content contains an oil component, the internal pressure of the accumulator space required to lower the plunger body with respect to the sub-cylinder increases, and before this lowering occurs, there is a risk that the sub-piston may be deformed so as to stick to the inner peripheral surface of the lower cylinder by the internal pressure of the accumulator space. When such sticking occurs, it becomes difficult for the plunger body to descend with respect to the sub-cylinder, and the pressing force of the pressing head required to discharge the content increases. This problem is particularly likely to appear when the ambient temperature where the discharger is placed is high because the sub-piston softens.

[0006] The present invention provides an accumulator type discharger capable of suppressing deformation of the sub-piston so as to stick to the inner peripheral surface of the lower cylinder when the pressing head is pushed down even if the discharged content contains an oil component.

Means for Solving the Problem

[0007] The accumulative discharge device according to one aspect of the present invention includes a main cylinder that extends in the vertical direction and communicates with the inside of the container body, a plunger body that protrudes upward from within the main cylinder and is supported so as to be movable downward in an upwardly biased state, a pressing head provided above the plunger body and having a discharge hole through which the content is discharged, an upper cylinder body to which the pressing head is attached, and a lower cylinder body in which the upper end portion of the plunger body is accommodated so as to be movable downward inside, and a sub-cylinder having a communication hole formed therein for vertically communicating the inside of the upper cylinder body and the inside of the lower cylinder body. The plunger body includes a main piston that is fitted into the main cylinder so as to be movable downward, a sub-piston that is fitted into the lower cylinder so as to be movable downward, an upper valve body that closes the communication hole from below the communication hole, and a communication passage that communicates the pressure accumulation space partitioned by the sub-piston and having the communication hole opened in the lower cylinder body with the inside of the main cylinder. The sub-piston includes an upper seal cylinder portion that extends radially outward as it goes from below to above, a lower seal cylinder portion that extends radially outward as it goes from above to below, and a plurality of vertical ribs that connect the outer peripheral surfaces of the portions of the upper seal cylinder portion located below the upper end portion and the outer peripheral surfaces of the portions of the lower seal cylinder portion located above the lower end portion in the vertical direction and are arranged at intervals in the circumferential direction. The vertical ribs are located radially inside the upper end portion of the upper seal cylinder portion and the lower end portion of the lower seal cylinder portion.

[0008] Since the sub-piston includes a plurality of vertical ribs that connect the outer peripheral surfaces of the upper seal cylinder portion and the outer peripheral surfaces of the lower seal cylinder portion in the vertical direction and are arranged at intervals in the circumferential direction, even if the sub-piston attempts to deform so as to stick to the inner peripheral surface of the lower cylinder body as the internal pressure in the pressure accumulation space increases, the vertical ribs will serve as beams and restrict the deformation of the sub-piston. Therefore, even if the content to be discharged contains an oil component and the internal pressure in the pressure accumulation space tends to increase, it is possible to suppress the sub-piston from deforming so as to stick to the inner peripheral surface of the lower cylinder body when the pressing head is pushed down. The vertical rib connects the outer peripheral surfaces of the upper seal cylinder part at a position below the upper end part and the outer peripheral surfaces of the lower seal cylinder part at a position above the lower end part in the vertical direction, and is located radially inside the upper end part of the upper seal cylinder part and the lower end part of the lower seal cylinder part. Therefore, it is possible to prevent the vertical rib from coming into contact with the inner peripheral surface of the lower cylinder body. By providing the vertical rib, it is possible to prevent the pressing force of the pressing head required to discharge the contents from becoming too high.

Effect of the Invention

[0009] According to the accumulator type discharger of the present invention, even if the discharged content contains an oil component, it is possible to suppress the deformation of the sub-piston so that it adheres to the inner peripheral surface of the lower cylinder body when the pressing head is pushed down.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a discharge container configured by attaching an accumulator type discharger to a container body will be described as an example. As shown in FIG. 1, the discharge container 1 of the present embodiment includes a bottomed cylindrical container body 2 in which the content is stored, and an accumulator type discharger 3 detachably attached to the mouth portion 2a of the container body 2. The content stored in the container body 2 of the present embodiment contains an oil component.

[0012] The accumulator type discharger 3 has a pressing head 11 in which a discharge hole 10 for discharging the content is formed, and a pump 12 for supplying the content toward the discharge hole 10. The pump 12 mainly includes a mounting cap 21, a main cylinder 22, a sub-cylinder 23, and a plunger body 24.

[0013] Here, the mounting cap 21, the main cylinder 22, the sub-cylinder 23, and the plunger body 24 are each formed in a cylindrical shape and are arranged with their respective central axes located on a common axis. Hereinafter, this common axis is referred to as axis O, the side of the pressing head 11 along the axis O is referred to as upward, the side of the container body 2 along the axis O is referred to as downward, and the direction along the axis O is referred to as the vertical direction. The direction intersecting the axis O as viewed from the vertical direction is referred to as the radial direction, and the direction orbiting around the axis O as viewed from the vertical direction is referred to as the circumferential direction.

[0014] Among the mounting cap 21, an annular plate portion 32 protruding radially inward is formed at the upper end of the mounting cylinder 31 externally fitted to the mouth portion 2a of the container body 2. The annular plate portion 32 faces the upper end opening edge of the mouth portion 2a in the vertical direction over the entire circumference. A cap cylinder 33 extending upward is formed on the outer peripheral portion of the annular plate portion 32. An overcap (not shown) is externally fitted to the cap cylinder 33. A guide cylinder 34 extending upward is formed at the inner peripheral edge of the annular plate portion 32. A locking projection 38 protruding radially inward and continuously extending over the entire circumference is formed at the upper end portion of the guide cylinder 34.

[0015] The main cylinder 22 is disposed inside the container body 2 in a state where the mounting cap 21 is mounted on the container body 2, and the lower end opening communicates with the inside of the container body 2. The main cylinder 22 has a cylinder tube 35 extending in the vertical direction and a mounting flange 36 protruding radially outward from the upper end portion of the cylinder tube 35 and continuously extending over the entire circumference. The mounting flange 36 is disposed at the upper end opening edge of the mouth portion 2a via a packing. The upper surface of the mounting flange 36 abuts against the lower surface of the annular plate portion 32 of the mounting cap 21. The cylinder tube 35 has a base tube portion 41, a valve seat portion 42, and a connecting tube portion 43.

[0016] The base cylinder part 41 is formed in a multi-stage cylindrical shape with a smaller diameter towards the lower part. Inside the base cylinder part 41, a rod 45 extending in the vertical direction is accommodated. The rod 45 is formed with a smaller diameter than the inner diameter of the base cylinder part 41. At the lower end of the rod 45, a plurality of ribs 46 protruding in the radial direction are formed at intervals in the circumferential direction. The valve seat part 42 extends downward from the lower end of the base cylinder part 41 and extends inward in the radial direction as it goes downward. Inside the valve seat part 42, a lower valve body 51 is accommodated, and the lower valve body 51 is detachably in contact with the inner peripheral surface of the valve seat part 42. The lower valve body 51 is formed in a spherical shape. The lower valve body 51 switches the communication and cutoff between the inside of the main cylinder 22 and the inside of the container body 2 according to the internal pressure of the main cylinder 22. The connecting cylinder part 43 extends straight downward from the lower end of the valve seat part 42. The upper end part of a suction cylinder 55 is fitted inside the connecting cylinder part 43. The lower end of the suction cylinder 55 is located inside the bottom of the container body 2.

[0017] The plunger body 24 has a first plunger 61 and a second plunger 62 arranged coaxially with the axis O.

[0018] The first plunger 61 is formed in a toped cylindrical shape having a top part and a cylindrical part. The first plunger 61 protrudes upward from inside the main cylinder 22 with the lower part of the cylindrical part being accommodated inside the main cylinder 22. The cylindrical part of the first plunger 61 is formed in a multi-stage cylindrical shape with an increasing diameter towards the lower part. The upper part of the above-mentioned rod 45 is inserted inside the lower part of the cylindrical part of the first plunger 61. The first plunger 61 is provided so as to be movable in the vertical direction with respect to the main cylinder 22 and the rod 45. A through hole 63 penetrating the first plunger 61 in the radial direction is formed at the upper end part of the cylindrical part of the first plunger 61. A main piston 65 is formed at the lower end part of the cylindrical part of the first plunger 61. The main piston 65 extends outward in the radial direction as it goes downward. The main piston 65 is fitted movably downward inside the base cylinder part 41 of the main cylinder 22. Here, in the main cylinder 22, a biasing member 66 that biases the first plunger 61 upward is provided at a portion located between the first plunger 61 and the rib 46 described above. Thereby, the plunger body 24 is supported so as to be movable downward while being biased upward with respect to the main cylinder 22. The top of the first plunger 61 is formed in a rod shape extending in the vertical direction. An upper valve body 71 having a conical shape that tapers upward is formed at the upper end of the top of the first plunger 61. The upper valve body 71 closes a communication hole 85 (to be described later) of the sub-cylinder 23 from below the communication hole 85. A communication groove 70 that communicates the through hole 63 described above with the inside of the sub-cylinder 23 is formed on the outer peripheral surface of a portion of the top of the first plunger 61 that is located below the upper valve body 71. The communication groove 70 is recessed inward in the radial direction and extends in the vertical direction. The lower end of the communication groove 70 faces the through hole 63 in the radial direction. The upper end of the communication groove 70 opens upward adjacent to the lower edge of the upper valve body 71 in the radial direction.

[0019] The second plunger 62 is formed in a cylindrical shape. The second plunger 62 is externally fitted to the first plunger 61, protrudes upward from the upper end portion of the main cylinder 22, and is located below the upper end portion of the upper valve body 71. A sub-piston 72 that protrudes radially outward from the second plunger 62 is provided at the upper end of the second plunger 62. The sub-piston 72 is located below the upper end portion of the upper valve body 71. The sub-piston 72 is fitted so as to be movable downward in a lower cylindrical body 74 (to be described later) of the sub-cylinder 23.

[0020] As shown in FIG. 2, the sub-piston 72 includes an upper seal cylinder portion 13, a lower seal cylinder portion 14, and a plurality of vertical ribs 15.

[0021] The upper seal cylinder portion 13 extends outward in the radial direction from bottom to top. The lower seal cylinder portion 14 extends outward in the radial direction from top to bottom. In a longitudinal sectional view along the vertical direction, the length of the upper seal cylinder portion 13 is longer than the length of the lower seal cylinder portion 14. The outer peripheral surfaces of the upper end portion 13a of the upper seal cylinder portion 13 and the lower end portion 14a of the lower seal cylinder portion 14 linearly extend in the vertical direction in the longitudinal sectional view. The outer diameters of the upper end portion 13a of the upper seal cylinder portion 13 and the lower end portion 14a of the lower seal cylinder portion 14 are larger than the inner diameter of a lower cylinder body 74 of the sub-cylinder 23 described later. Among the sub-pistons 72, the outer peripheral surface of the portion located between the upper end portion 13a of the upper seal cylinder portion 13 and the lower end portion 14a of the lower seal cylinder portion 14 presents a curved shape that is recessed inward in the radial direction in the longitudinal sectional view.

[0022] The plurality of vertical ribs 15 connect the outer peripheral surfaces of the portion of the upper seal cylinder portion 13 located below the upper end portion 13a and the portion of the lower seal cylinder portion 14 located above the lower end portion 14a in the vertical direction, and are arranged at intervals in the circumferential direction. The vertical ribs 15 are connected to the outer peripheral surface of the sub-piston 72 over the entire vertical length. Sixteen vertical ribs 15 are provided at equal intervals in the circumferential direction. The vertical ribs 15 present a triangular shape that tapers outward in the radial direction in a cross-sectional view along the radial direction. The vertical ribs 15 are formed in a triangular prism shape extending in the vertical direction. The interval between adjacent vertical ribs 15 in the circumferential direction is larger than the circumferential dimension of the vertical ribs 15. The radial distance between the outer end portion of the vertical rib 15 in the radial direction and the axis O is equal to or less than the radius of the inner peripheral surface of the lower cylinder body 74 of the sub-cylinder 23 described later. The vertical ribs 15 are located radially inward of the upper end portion 13a of the upper seal cylinder portion 13 and the lower end portion 14a of the lower seal cylinder portion 14. The vertical ribs 15 are vertically separated from the upper end portion 13a of the upper seal cylinder portion 13 and the lower end portion 14a of the lower seal cylinder portion 14.

[0023] As shown in FIG. 1, the sub-cylinder 23 includes a lower cylinder body 74, a closing plate 75 protruding radially inward from the lower cylinder body 74, and an upper cylinder body 76 extending upward from the closing plate 75.

[0024] The upper end portion of the plunger body 24 is accommodated in the lower cylinder body 74 so as to be movable downward. The lower cylinder body 74 is inserted into the guide cylinder 34 so as to be movable vertically therein with its upper portion protruding upward from the guide cylinder 34. A retaining portion 82 protruding radially outward is formed at the lower end portion of the lower cylinder body 74. The retaining portion 82 engages with the locking projection 38 of the guide cylinder 34 described above from below the locking projection 38. Thereby, further upward movement of the sub-cylinder 23 is restricted.

[0025] The closing plate 75 protrudes radially inward from the intermediate portion in the vertical direction on the inner peripheral surface of the lower cylinder body 74. A communication hole 85 penetrating the closing plate 75 in the vertical direction is formed at the central portion in the radial direction of the closing plate 75. The communication hole 85 is arranged coaxially with the axis O. The communication hole 85 vertically communicates the upper cylinder body 76 and the lower cylinder body 74. The outer peripheral surface of the upper valve body 71 described above is detachably abutted against the opening peripheral edge portion of the communication hole 85 on the lower surface of the closing plate 75. The upper valve body 71 switches the communication and cutoff between the pressure accumulation space Y communicated through the communication hole 85 and the discharge hole 10 according to the internal pressure of the pressure accumulation space Y partitioned by the sub-piston 72 and having the communication hole 85 opened in the lower cylinder body 74.

[0026] The upper end portion of the communication groove 70 provided in the plunger body 24 opens in the pressure accumulation space Y. Thereby, the pressure accumulation space Y communicates with the inside of the main cylinder 22 through the communication groove 70, the through hole 63, and the inside of the cylinder portion of the first plunger 61. The communication groove 70, the through hole 63, and the inside of the cylinder portion of the first plunger 61 constitute a communication path R provided in the plunger body 24 and communicating the pressure accumulation space Y and the inside of the main cylinder 22.

[0027] The pressing head 11 is attached to the upper cylinder body 76. The inside of the upper cylinder body 76 communicates with the discharge hole 10. The upper cylinder body 76 extends upward from a portion of the closing plate 75 that is located radially outside the communication hole 85. The upper end opening edge of the upper cylinder body 76 is located above the upper end opening edge of the lower cylinder body 74.

[0028] The pressing head 11 is provided above the plunger body 24 and has a discharge hole 10 through which the content is discharged. The pressing head 11 is formed in a toped cylindrical shape. A fitting cylinder 87 that extends downward is formed at the radial center of the top wall portion of the pressing head 11. The fitting cylinder 87 is externally fitted to the above-described upper cylinder body 76. A discharge hole 10 that opens radially outward is formed in the peripheral wall portion of the pressing head 11. The discharge hole 10 communicates with the communication hole 85 through the inside of the fitting cylinder 87.

[0029] Next, the operation of the above-described discharge container 1 will be described.

[0030] When the pressing head 11 is pushed down, the sub-cylinder 23 and the plunger body 24 are pushed down together with the pressing head 11. At this time, the main piston 65 slides downward in the base cylinder portion 41 of the cylinder barrel 35, thereby pressurizing the inside of the base cylinder portion 41. As a result, the content in the main cylinder 22 flows into the cylinder portion of the first plunger 61 in the communication path R, and then passes through the through hole 63 of the first plunger 61 and the communication groove 70 in this order, and flows into the pressure accumulation space Y in the lower cylinder body 74, thereby pressurizing the pressure accumulation space Y.

[0031] When the internal pressure of the pressure accumulation space Y exceeds a predetermined value, the plunger body 24 descends with respect to the sub-cylinder 23 against the upward biasing force of the biasing member 66. At this time, the upper valve body 71 separates downward from the opening peripheral edge portion of the communication hole 85 on the lower surface of the closing plate 75, thereby opening the communication hole 85. As a result, the pressure accumulation space Y communicates with the discharge hole 10 through the communication hole 85 and the inside of the upper cylinder body 76, and the content of the pressure accumulation space Y is discharged to the outside through the discharge hole 10.

[0032] Before the pressing head 11 reaches the lowered end position, if the internal pressure of the pressure accumulation space Y decreases as the content is discharged, the plunger body 24 rises with respect to the sub-cylinder 23 due to the upward biasing force of the biasing member 66, and the upper valve body 71 abuts against the opening peripheral edge of the communication hole 85 on the lower surface of the closing plate 75 from below the closing plate 75, thereby closing the communication hole 85.

[0033] When the pressing of the pressing head 11 is released, the plunger body 24 is pushed up together with the sub-cylinder 23 and the pressing head 11 by the upward biasing force of the biasing member 66. In the process of the plunger body 24 being pushed up, the main piston 65 slides upward in the base cylinder portion 41, thereby reducing the pressure in the main cylinder 22. Then, the lower valve body 51 separates upward from the inner peripheral surface of the valve seat portion 42, so that the inside of the main cylinder 22 communicates with the inside of the container body 2 through the suction cylinder 55. As a result, the content in the container body 2 flows into the main cylinder 22 through the suction cylinder 55. Thereafter, as the internal pressure of the main cylinder 22 rises, the lower valve body 51 seats on the inner peripheral surface of the valve seat portion 42, and the communication between the inside of the main cylinder 22 and the inside of the container body 2 is blocked.

[0034] As described above, according to the pressure accumulation type discharger 3 of the present embodiment, the sub-piston 72 connects the outer peripheral surfaces of the upper seal cylinder portion 13 and the outer peripheral surfaces of the lower seal cylinder portion 14 in the vertical direction and is provided with a plurality of vertical ribs 15 spaced apart in the circumferential direction. Therefore, even if the sub-piston 72 tries to deform so as to stick to the inner peripheral surface of the lower cylinder body 74 as the internal pressure of the pressure accumulation space Y rises, the vertical ribs 15 serve as beams and restrict the deformation of the sub-piston 72. Therefore, even if the discharged content contains an oil component and the internal pressure of the pressure accumulation space Y tends to be high, it is possible to suppress the sub-piston 72 from deforming so as to stick to the inner peripheral surface of the lower cylinder body 74 when the pressing head 11 is pushed down.

[0035] The vertical rib 15 connects the outer peripheral surfaces of the upper seal cylinder part 13 at a portion located below the upper end part 13a and the outer peripheral surfaces of the lower seal cylinder part 14 at a portion located above the lower end part 14a in the vertical direction, and is located radially inward of the upper end part 13a of the upper seal cylinder part 13 and the lower end part 14a of the lower seal cylinder part 14. Therefore, it is possible to prevent the vertical rib 15 from coming into contact with the inner peripheral surface of the lower cylindrical body 74. By providing the vertical rib 15, it is possible to prevent the pressing force of the pressing head 11 required to discharge the content from becoming too high.

[0036] Next, the verification test will be described. The discharge container 1 shown in FIGS. 1 and 2 was adopted as an example, and a discharge container having the same structure as the discharge container 1 except that it does not have the vertical rib 15 was adopted as a comparative example. All the discharge containers were filled with the same content containing oil. After setting the speed of pushing down the pressing head (40 mm / s) to be the same, the pressing force applied to the pressing head to reach the lower end position was measured. The temperature of the content in the container body was made different at 20°C, 40°C, and 5°C, and the number N of each of the example and the comparative example was 3 for each temperature. When the pressing force exceeds 35 N, it becomes quite difficult for even an adult male to push down the pressing head to reach the lower end position.

[0037]

Table 1

[0038] When comparing the average of the pressing force when the temperature of the content in the container body is the same between the example and the comparative example, the example is suppressed lower than the comparative example. Also, when comparing the variation in the pressing force when the temperature of the content is the same between the example and the comparative example, it was confirmed that the example is suppressed smaller than the comparative example. In the comparative example, when the temperature of the content was 40°C, it was confirmed once that when the pressing head was pushed down, the sub-piston was deformed so as to stick to the inner peripheral surface of the lower cylindrical body and the pressing force became 37.2 N.

[0039] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes and the like within the scope not departing from the gist of the present invention are also included. That is, within the scope not departing from the gist of the present invention, it is possible to appropriately replace the components in the above-described embodiments with well-known components.

Explanation of Reference Numerals

[0040] 1... discharge container 2... container body 2a... mouth portion 3... accumulator type discharger 10... discharge hole 11... push head 13... upper seal cylinder portion 13a... upper end portion of the upper seal cylinder portion 14... lower seal cylinder portion 14a... lower end portion of the lower seal cylinder portion 15... vertical rib 22... main cylinder 23... sub-cylinder 24... plunger body 65... main piston 71... upper valve body 72... sub-piston 74... lower cylinder 76... upper cylinder 85... communication hole R... communication path Y... accumulator space

Claims

【Claim 1】 A main cylinder extending in the vertical direction and having an inner side communicating with the inside of the container body; A plunger body protruding upward from within the main cylinder and supported so as to be movable downward in an upwardly biased state; A push head provided above the plunger body and having a discharge hole through which the content is discharged; A sub-cylinder having an upper cylinder body to which the push head is attached and a lower cylinder body in which the upper end portion of the plunger body is accommodated so as to be movable downward inside, and having a communication hole formed to communicate the inside of the upper cylinder body and the inside of the lower cylinder body in the vertical direction; The plunger body includes: A main piston fitted so as to be movable downward within the main cylinder; A sub-piston fitted so as to be movable downward within the lower cylinder; An upper valve body closing the communication hole from below the communication hole; A communication passage communicating a pressure accumulation space partitioned by the sub-piston within the lower cylinder and having the communication hole opened and the inside of the main cylinder; The sub-piston includes: An upper seal cylinder portion extending outward in the radial direction as it goes from below to above; A lower seal cylinder portion extending outward in the radial direction as it goes from above to below; A plurality of vertical ribs connecting the outer peripheral surfaces of portions of the upper seal cylinder portion located below the upper end portion and the outer peripheral surfaces of portions of the lower seal cylinder portion located above the lower end portion in the vertical direction and arranged at intervals in the circumferential direction; The vertical ribs are located radially inward of the upper end portion of the upper seal cylinder portion and the lower end portion of the lower seal cylinder portion, a pressure accumulation type discharger.

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