Accumulator used for hydraulic damper

Abstract

To provide an accumulator used for a hydraulic damper, capable of suppressing an increase in the size of the hydraulic damper by shortening the axial length size.SOLUTION: An accumulator 26 has a free piston 27 fitted and inserted into a piston rod 9 of a hydraulic damper 2 slidably in the axial direction. An oil chamber 28 is defined and formed on one axial side of the free piston 27, and the oil chamber 28 sucks / discharges working oil between a first pressure chamber 7 and a second pressure chamber 8 of the hydraulic damper 2. A sealed chamber 29 the internal of which is sealed is defined and formed on the other axial side of the free piston 27. A flow path 34 is provided for communicating the sealed chamber 29 with the external. In the flow path 34, a check valve 35 is arranged in the direction of allowing the suction from the external into the sealed chamber 29 and preventing the discharge from the sealed chamber 29 to the external.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an accumulator used for a hydraulic damper for a building or the like that attenuates vibration external forces caused by earthquakes, winds, etc. according to the discharge and inhalation of hydraulic oil in the pressure chamber of a cylinder.

Background Art

[0002] A hydraulic damper using this type of accumulator includes a first pressure chamber and a second pressure chamber filled with hydraulic oil on both sides of a piston that reciprocates in a cylinder, and a control valve (pressure regulating valve) is disposed in a control flow path that communicates the two pressure chambers. When a vibration external force such as an earthquake or wind acts and the piston reciprocates, the pressure in one of the pressure chambers rises, and hydraulic oil flows from this pressure chamber toward the other pressure chamber. Along with the flow of this hydraulic oil, a damping force is generated by the control valve, and a damping effect on the vibration is obtained to reduce the sway of the building.

[0003] The accumulator is housed in a piston rod that protrudes axially from the piston, and the oil chamber of the accumulator communicates with both pressure chambers via a control valve and a check valve arranged in parallel with the control valve, absorbing the thermal expansion of the hydraulic oil filled in both pressure chambers, or replenishing the hydraulic oil to the pressure chamber where the volume increases due to the reciprocating movement of the piston and becomes low pressure to prevent this pressure chamber from becoming negative pressure.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the accumulator used in such a conventional hydraulic damper, a free piston that is slidably inserted into the inside of the piston rod to partition and form an oil chamber is biased toward the oil chamber side, and a spring for setting the pressure of the oil chamber is provided. The spring is interposed between the free piston and a lid member fixed to the tip of the piston rod. For this reason, the accumulator requires the mounting dimensions and the close contact dimensions of the spring, and the axial length dimension between the free piston and the lid member must be increased. Along with this, the hydraulic damper has a problem that the axial length dimension of the piston rod becomes long, resulting in an increase in size and cost.

[0006] An object of the present invention is to provide an accumulator for a hydraulic damper that can shorten the axial length dimension and suppress the increase in size of the hydraulic damper.

Means for Solving the Problems

[0007] In order to achieve such a problem, the present invention takes the following means. That is, A first pressure chamber and a second pressure chamber filled with hydraulic oil are formed on both sides of a piston that reciprocates inside a cylinder. The piston is provided with a piston rod that protrudes to the outside through the pressure chamber. In an accumulator used in a hydraulic damper in which a control valve that generates a damping force by controlling the flow of hydraulic oil from one pressure chamber to the other pressure chamber is disposed in a control flow path that communicates the two pressure chambers, the accumulator slidably inserts a free piston axially inside the piston rod, partitions and forms an oil chamber that sucks and discharges hydraulic oil between the two pressure chambers on one axial side of the free piston, partitions and forms a sealed chamber with the inside sealed on the other axial side facing one axial side of the free piston, provides a flow path that communicates the sealed chamber with the outside, and a check valve is disposed in the flow path in a direction that allows suction from the outside to the sealed chamber and blocks discharge from the sealed chamber to the outside. This is the accumulator for a hydraulic damper.

[0008] In this case, a connection member formed by blocking off an accommodation chamber that houses the portion protruding outside the piston rod from the outside is provided in the hydraulic damper. The connection member is provided with a second flow path that communicates the accommodation chamber with the outside. A second check valve may be disposed in the second flow path in a direction that allows suction from the outside into the accommodation chamber and blocks discharge from the accommodation chamber to the outside.

Advantages of the Invention

[0009] As described in detail above, in the invention according to claim 1, the accumulator slidably inserts a free piston axially inside the piston rod, partitions and forms an oil chamber that sucks and discharges hydraulic oil between the two pressure chambers on one axial side of the free piston, seals the inside on the other axial side opposite to one axial side of the free piston to partition and form a sealed chamber, provides a flow path that communicates the sealed chamber with the outside, and disposes a check valve in the flow path in a direction that allows suction from the outside into the sealed chamber and blocks discharge from the sealed chamber to the outside. Therefore, when the free piston slides to the other axial side, the air in the sealed chamber is compressed, and when the free piston slides to one axial side, the free piston is pressed by the acting force based on the pressure of the air in the sealed chamber. Thus, the accumulator can eliminate the need for a spring, can shorten the axial length dimension, and can suppress the enlargement of the hydraulic damper. Further, a check valve is disposed in a direction that allows suction from the outside into the sealed chamber and blocks discharge from the sealed chamber to the outside. Therefore, since air can be inhaled into the sealed chamber from the outside, even when the free piston slides to one axial side, a pressure drop in the sealed chamber can be satisfactorily blocked.

[0010] Further, in the invention according to claim 2, a connection member formed by blocking off an accommodation chamber that houses the portion protruding outside the piston rod from the outside is provided in the hydraulic damper. The connection member is provided with a second flow path that communicates the accommodation chamber with the outside. A second check valve is disposed in the second flow path in a direction that allows suction from the outside into the accommodation chamber and blocks discharge from the accommodation chamber to the outside. Therefore, even when the portion protruding outside the piston rod is housed in the accommodation chamber of the connection member, since air can be inhaled into the accommodation chamber from the outside by the second check valve, the accumulator can satisfactorily block a pressure drop accompanying an increase in the volume of the sealed chamber.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0012] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In FIGS. 1 and 2, 1 is a cylinder of the hydraulic damper 2, a fitting hole 3 is formed to penetrate axially, an opening on one axial side of the fitting hole 3 is closed by a first cover member 4, and an opening on the other axial side opposite to one axial side of the fitting hole 3 is closed by a second cover member 5. 6 is a piston, which is axially reciprocally fitted into the fitting hole 3 of the cylinder 1. 7 is a first pressure chamber, which is partitioned and formed by the cylinder 1 and the first cover member 4 on one axial side of the piston 6 and filled with hydraulic oil inside. 8 is a second pressure chamber, which is partitioned and formed by the cylinder 1 and the second cover member 5 on the other axial side of the piston 6 and filled with hydraulic oil inside.

[0013] 9 is a piston rod, which has a first rod portion 10 and a second rod portion 11. The first rod portion 10 of the piston rod 9 projects on one axial side of the piston 6, penetrates the first pressure chamber 7 and the first cover member 4 in a liquid-tight manner, and the tip projects to the outside. A first spherical joint 12 for attaching to a beam of a building (not shown) is pivotally provided at the tip. The second rod portion 11 of the piston rod 9 projects on the other axial side of the piston 6, penetrates the second pressure chamber 8 and the second cover member 5 in a liquid-tight manner, and the tip projects outside the second cover member 5.

[0014] Reference numeral 13 denotes a connecting member integrally formed with the second cover member 5, which has a second spherical joint 14 (not shown) pivotally attached to a column of a building at its tip. The connecting member 13 is formed with a receiving chamber 13A that houses a portion of the second rod portion 11 of the piston rod 9 protruding outside, and is blocked from the outside. Reference numeral 15 denotes a pressure regulating valve as a control valve, which is disposed in a control flow path 16 that communicates the two pressure chambers 7 and 8 and is provided inside the piston 6. The control flow path 16 controls the flow of hydraulic oil from one of the pressure chambers 7 or 8 to the other pressure chamber 8 or 7 to generate a damping force.

[0015] Specifically, the control flow path 16 is composed of a first control flow path 17, a second control flow path 18, and a third control flow path 19. The first control flow path 17 communicates the two pressure chambers 7 and 8, and arranges a first control check valve 20 and a second control check valve 21 in series, with the first control check valve 20 on the first pressure chamber 7 side and the second control check valve 21 on the second pressure chamber 8 side. The first control check valve 20 is arranged in a direction that allows the flow of hydraulic oil from the first pressure chamber 7 side to the second pressure chamber 8 side and blocks the flow of hydraulic oil in the reverse direction. The second control check valve 21 is arranged in a direction that allows the flow of hydraulic oil from the second pressure chamber 8 side to the first pressure chamber 7 side and blocks the flow of hydraulic oil in the reverse direction.

[0016] The second control flow path 18 communicates the two pressure chambers 7 and 8 in parallel with the first control flow path 17, and arranges a third control check valve 22 and a fourth control check valve 23 in series, with the third control check valve 22 on the first pressure chamber 7 side and the fourth control check valve 23 on the second pressure chamber 8 side. The third control check valve 22 is arranged in a direction that blocks the flow of hydraulic oil from the first pressure chamber 7 side to the second pressure chamber 8 side and allows the flow of hydraulic oil in the reverse direction. The fourth control check valve 23 is arranged in a direction that blocks the flow of hydraulic oil from the second pressure chamber 8 side to the first pressure chamber 7 side and allows the flow of hydraulic oil in the reverse direction.

[0017] The third control flow path 19 communicates between the location where the first control check valve 20 is disposed and the location where the second control check valve 21 is disposed in the first control flow path 17, and between the location where the third control check valve 22 is disposed and the location where the fourth control check valve 23 is disposed in the second control flow path 18. The pressure regulating valve 15 is disposed in the third control flow path 19 to impart a predetermined flow resistance to the hydraulic oil flowing from the first control flow path 17 to the second control flow path 18.

[0018] 24 is the first relief valve, and 25 is the second relief valve, which are respectively provided on the piston 6. The first relief valve 24 discharges high-pressure hydraulic oil from the first pressure chamber 7 to the second pressure chamber 8, and the second relief valve 25 is arranged to discharge high-pressure hydraulic oil from the second pressure chamber 8 to the first pressure chamber 7.

[0019] 26 is an accumulator. A free piston 27 is slidably inserted axially inside the second rod portion 11 of the piston rod 9. An oil chamber 28 filled with hydraulic oil is partitioned and formed on one axial side (the side close to the piston 6) of the free piston 27, and a sealed chamber 29 is partitioned and formed by sealing the inside on the other axial side opposite to one axial side of the free piston 27.

[0020] The oil chamber 28 communicates with the connection flow path 30 formed in the piston rod 9 between the location where the third check valve 22 is disposed and the location where the fourth check valve 23 is disposed in the second control flow path 18, and sucks and discharges hydraulic oil between the two pressure chambers 7 and 8. A throttle 31 is disposed in the connection flow path 30. 32 is a lid member that partitions and forms the sealed chamber 29, and is attached to the tip of the second rod portion 11 of the piston rod 9.

[0021] The lid member 32 forms a contact portion 32A at the inner end where the free piston 27 slides and contacts in the axial direction of the other side, and regulates the maximum sliding amount of the free piston 27 in the axial direction of the other side. 33 is a second contact portion where the free piston 27 slides and contacts in the axial direction of one side, and is formed at the connecting step portion between the first rod portion 10 and the second rod portion 11 of the piston rod 9 to set the minimum volume of the oil chamber 28.

[0022] 34 is a flow path formed in the lid member 32, which communicates the sealed chamber 29 and the accommodation chamber 13A (outside). 35 is a check valve provided in the flow path 34, and is arranged in a direction that allows inhalation from the accommodation chamber 13A to the sealed chamber 29 and blocks discharge from the sealed chamber 29 to the accommodation chamber 13A.

[0023] 36 is a second flow path formed in the connection member 13, which communicates the accommodation chamber 13A and the outside. 37 is a second check valve provided in the second flow path 36, and is arranged in a direction that allows inhalation from the outside to the accommodation chamber 13A and blocks discharge from the accommodation chamber 13A to the outside.

[0024] Next, the operation of such a configuration will be described. In the state of FIG. 1, the first spherical joint 12 at the tip of the first rod portion 10 of the piston rod 9 of the hydraulic damper 2 is attached to a beam of a building (not shown), and the second spherical joint 14 at the tip of the connection member 13 is attached to a column of a building (not shown).

[0025] In this state, when a vibration external force such as an earthquake or wind acts on the hydraulic damper 2, for example, when the volume of the first pressure chamber 7 decreases and the volume of the second pressure chamber 8 increases, and the piston 6 moves forward in the right direction of FIG. 1, the pressure in the first pressure chamber 7 rises. As a result, the hydraulic oil in the first pressure chamber 7 flows into the second pressure chamber 8 through the first control check valve 20, the pressure regulating valve 15, and the fourth control check valve 23. At this time, when the hydraulic oil passes through the pressure regulating valve 15, a flow resistance is applied, and the forward movement speed of the piston 6 is reduced.

[0026] When the pressure of the hydraulic oil in the first pressure chamber 7 becomes equal to or higher than the set pressure of the first relief valve 24, the first relief valve 24 also opens, and the hydraulic oil in the first pressure chamber 7 flows into the second pressure chamber 8 through the first relief valve 24, preventing the pressure of the hydraulic oil from becoming too high and damaging the equipment.

[0027] When the direction of the external force changes and, conversely, the piston 6 moves backward in the left direction of FIG. 1 where the volume of the second pressure chamber 8 decreases and the volume of the first pressure chamber 7 increases, the pressure in the second pressure chamber 8 rises. As a result, the hydraulic oil in the second pressure chamber 8 flows into the first pressure chamber 7 through the second control check valve 21, the pressure regulating valve 15, and the third control check valve 22. At this time, a flow resistance is applied when the hydraulic oil passes through the pressure regulating valve 15, reducing the backward movement speed of the piston 6.

[0028] When the pressure of the hydraulic oil in the second pressure chamber 8 becomes equal to or higher than the set pressure of the second relief valve 25, the second relief valve 25 also opens, and the hydraulic oil in the second pressure chamber 8 flows into the first pressure chamber 7 through the second relief valve 25, preventing the hydraulic oil pressure from becoming too high and damaging the equipment.

[0029] In this way, when the piston 6 reciprocates due to the external force of vibration, a damping force is generated according to the flow resistance of the hydraulic oil by the pressure regulating valve 15, and the vibration is attenuated. When the piston 6 moves forward, for example, when the pressure of the hydraulic oil in the second pressure chamber 8 becomes negative pressure, the accumulator 26 slides axially on one side where the volume of the oil chamber 28 decreases due to the acting force based on the pressure of the air in the sealed chamber 29 of the free piston 27, and the hydraulic oil in the oil chamber 28 flows into the second pressure chamber 8 through the connecting flow path 30, the throttle 31, the second control flow path 18, and the fourth control check valve 23, preventing the damping effect from decreasing. As the free piston 27 slides axially on one side, the volume of the sealed chamber 29 of the accumulator 26 increases, and external air is inhaled through the second check valve 37, the housing chamber 13A, and the check valve 35.

[0030] Also, when the piston 6 moves backward and the pressure of the hydraulic oil in the first pressure chamber 7 becomes negative pressure, similarly, the accumulator 26 has the free piston 27 pressed, and the hydraulic oil in the oil chamber 28 flows into the first pressure chamber 7 from the second control flow path 18 through the third control check valve 22, preventing the damping effect from decreasing. The volume of the sealed chamber 29 of the accumulator 26 increases, and external air is inhaled through the second check valve 37, the housing chamber 13A, and the check valve 35.

[0031] When the amount of working oil increases due to thermal expansion caused by a change in the temperature of the working oil, the working oil in the first pressure chamber 7 flows into the oil chamber 28 through the first control check valve 20, the pressure regulating valve 15, the throttle 31, and the connecting passage 30. Also, the working oil in the second pressure chamber 8 similarly flows into the oil chamber 28 from the second control check valve 21. When the working oil flows into the oil chamber 28, the accumulator 26 causes the free piston 27 to slide axially toward the other side, compressing the air in the sealed chamber 29 and reducing the volume of the sealed chamber 29.

[0032] In such an operation, the accumulator 26 slidably inserts the free piston 27 axially inside the piston rod 9, partitions and forms an oil chamber 28 that sucks and discharges the working oil between the two pressure chambers 7 and 8 on one axial side of the free piston 27, partitions and forms a sealed chamber 29 with its interior sealed on the other axial side opposite to one axial side of the free piston 27, provides a passage 34 that communicates the sealed chamber 29 with the accommodation chamber 13A (external), and disposes a check valve 35 in the passage 34 in a direction that allows inhalation from the accommodation chamber 13A to the sealed chamber 29 and blocks discharge from the sealed chamber 29 to the accommodation chamber 13A. For this reason, when the free piston 27 slides axially toward the other side, the air in the sealed chamber 29 is compressed, and when the free piston 27 slides axially toward one side, the free piston 27 is pressed by the acting force based on the pressure of the air in the sealed chamber 29. Therefore, the accumulator 26 can eliminate the need for a spring, can shorten the axial length dimension, and can suppress an increase in the size of the hydraulic damper 2.

[0033] Also, a check valve 35 is disposed in a direction that allows inhalation from the outside to the sealed chamber 29 and blocks discharge from the sealed chamber 29 to the outside. For this reason, since air can be inhaled into the sealed chamber 29 from the outside, even when the free piston 27 slides axially toward one side, a pressure drop in the sealed chamber 29 can be satisfactorily blocked.

[0034] In addition, a connection member 13 is provided in the hydraulic damper 2, which forms an accommodation chamber 13A that houses the portion of the piston rod 9 protruding to the outside and is blocked from the outside. The connection member 13 is provided with a second flow path 36 that communicates the accommodation chamber 13A with the outside, and a second check valve 37 is disposed in the second flow path 36 in a direction that allows suction from the outside to the accommodation chamber 13A and blocks discharge from the accommodation chamber 13A to the outside. Therefore, even if the portion of the piston rod 9 protruding to the outside is housed in the accommodation chamber 13A of the connection member 13, air can be inhaled from the outside into the accommodation chamber 13A by the second check valve 37, so the accumulator 26 can satisfactorily prevent the pressure drop associated with the increase in the volume of the sealed chamber 29.

[0035] In one embodiment, the pressure regulating valve 15 is used as the control valve, but an on-off valve may be used as the control valve. Also, although the pressure regulating valve 15 is provided inside the piston 6, it goes without saying that it may be provided outside the cylinder 1.

Explanation of Reference Numerals

[0036] 1: Cylinder 2: Hydraulic damper 6: Piston 7: First pressure chamber 8: Second pressure chamber 9: Piston rod 15: Pressure regulating valve (control valve) 26: Accumulator 27 Free piston 28: Oil chamber 29: Sealed chamber 34: Flow path 35: Check valve

Claims

1. An accumulator used in a hydraulic damper that forms a first pressure chamber and a second pressure chamber filled with hydraulic oil on both sides of a piston that reciprocates inside a cylinder, the piston is provided with a piston rod that penetrates the pressure chamber and protrudes to the outside, and a control valve that controls the flow of hydraulic oil from one pressure chamber to the other pressure chamber in a control flow path connecting both pressure chambers to generate a damping force is disposed. In the accumulator, the accumulator fits a free piston slidably in the axial direction inside the piston rod, partitions and forms an oil chamber on one axial side of the free piston that sucks and discharges hydraulic oil between both pressure chambers, partitions and forms a sealed chamber with the inside sealed on the other axial side opposite to one axial side of the free piston, provides a flow path that communicates the sealed chamber with the outside, and disposes a check valve in the flow path in a direction that allows suction from the outside to the sealed chamber and blocks discharge from the sealed chamber to the outside. The accumulator used in the hydraulic damper is characterized by this.

2. A connection member is provided in the hydraulic damper, which forms a housing chamber that houses a portion protruding outside the piston rod and is blocked from the outside. The connection member is provided with a second flow path that communicates the housing chamber with the outside, and a second check valve is disposed in the second flow path in a direction that allows suction from the outside to the housing chamber and blocks discharge from the housing chamber to the outside. The accumulator used in the hydraulic damper according to claim 1 is characterized by this.

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