Pressure motor type mass damper

Abstract

To provide a pressure motor type mass damper appropriately discharging working fluid in a housing of a pressure motor so as to securely prevent the housing from being excessively highly pressurized.SOLUTION: A pressure motor type mass damper 1 includes: a piston 3 sliding in a cylinder 2 filled with working fluid HF and sectioning into first and second fluid chambers 2e, 2f; a communication passage 4 bypassing the piston 3 and communicated to the first and second fluid chambers 2e, 2f; a gear motor 5 having a housing 6 communicated to the communication passage 4 and converting circulation of the working fluid HF into rotary motion; and a fly wheel 9 rotatably driven by the gear motor 5 and exhibiting vibration suppression effect. Furthermore, the mass damper 1 includes: an accumulator 21 for accumulating pressure due to inflow of the working fluid HF into the housing 6; and a drain piping 27 connected to the accumulator 21 and the communication passage 4 and attached with a nonreturn valve 28 for permitting flow of the working fluid HF from the accumulator 21 to the communication passage 4 side.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a pressure motor type mass damper that uses a pressure motor to convert the pressure of a working fluid generated with the vibration of a structure into the rotational motion of a rotating mass for seismic control or seismic isolation of structures and the like.

Background Art

[0002] As a conventional pressure motor type mass damper, for example, a hydraulic motor type disclosed in Patent Document 1 is known. In the mass damper described in FIG. 6 thereof, the hydraulic motor has a drain passage for discharging the hydraulic oil, and an accumulator is connected to the drain passage. The accumulator is, for example, a spring type having a casing, a piston, and a set spring, and the casing communicates with the drain passage. In this configuration, when the pressure in the housing of the hydraulic motor rises during the operation of the mass damper, the pressure is transmitted to the accumulator through the drain passage and stored. Thereby, the high pressure in the housing is prevented, so that, for example, the function of the seal of the output shaft of the hydraulic motor is maintained and the life can be extended.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional mass damper configured as described above, for example, when the mass damper operates for a long time due to the response of the structure to long-period seismic motion input, the amount of hydraulic oil in the casing of the accumulator increases and may reach a full state with respect to its capacity. In that case, the accumulator's pressure accumulation function can no longer be exerted, and due to the high pressure in the housing, problems such as hydraulic oil leaking from the seal part of the output shaft may occur.

[0005] The present invention has been made to solve the above problems, and an object thereof is to provide a pressure motor type mass damper that can surely prevent excessive high pressure in the housing by appropriately discharging the working fluid in the housing of the pressure motor.

Means for Solving the Problems

[0006] To achieve this object, the pressure motor type mass damper according to the invention of claim 1 includes a cylinder filled with a working fluid, a piston slidably provided in the cylinder and partitioning the inside of the cylinder into a first fluid chamber and a second fluid chamber, a communication passage bypassing the piston and communicating with the first and second fluid chambers, a housing having a drain passage communicating with the communication passage and for discharging the working fluid, and a pressure motor having a rotating body housed in the housing and converting the flow of the working fluid accompanying the sliding of the piston into the rotational motion of the rotating body, a flywheel rotationally driven by the rotating body and exerting a vibration suppression effect, an accumulator for storing pressure when the working fluid in the housing flows in, and a drain pipe connected to the communication passage from the accumulator and provided with an on-off valve allowing the flow of the working fluid from the accumulator to the communication passage side for discharging the working fluid from the accumulator to the first and / or second fluid chambers.

[0007] The mass damper of the present invention is of a pressure motor type. As the piston in the cylinder slides, the working fluid flows into the communication passage and the housing of the pressure motor, and the pressure of the working fluid due to the flow is converted into the rotational motion of the rotating body of the pressure motor, and the flywheel is rotationally driven, thereby exerting a vibration suppression effect. Further, as the pressure motor operates, the working fluid in the housing flows into the accumulator, so that pressure is stored in the accumulator, thereby preventing the pressure in the housing from increasing.

[0008] Furthermore, for example, when the mass damper operates for a long time and the amount of the working fluid in the accumulator increases, the on-off valve provided in the drain pipe opens, so that the working fluid flows from the accumulator into the communication passage through the drain pipe and is further discharged into the first and / or second fluid chambers. As a result, the accumulator does not become full, and the pressure accumulation function is maintained, thereby reliably preventing excessive pressure increase in the housing of the pressure motor. As a result, for example, the function of the seal of the output shaft of the pressure motor can be maintained and the life can be extended.

[0009] The invention according to claim 2 is characterized in that, in the pressure motor type mass damper according to claim 1, the drain pipe is connected to either one side of the first fluid chamber and the second fluid chamber of the communication passage.

[0010] According to this configuration, the drain pipe is arranged only on one side of the first fluid chamber or the second fluid chamber of the communication passage, and the working fluid flows from the accumulator to the communication passage through the drain pipe and is discharged into one of the first or second fluid chambers. In this way, even when the drain pipe is arranged only on one fluid chamber side, as the piston reciprocates during vibration, the fluid chamber repeatedly becomes a high-pressure state and a low-pressure state. Therefore, when in the low-pressure state, the discharge of the working fluid from the accumulator to the fluid chamber can be surely performed. Further, since the working fluid is appropriately discharged from the accumulator, the capacity of the accumulator may be small. Thus, in combination with the above-described arrangement of the drain pipe on one side, miniaturization and cost reduction of the accumulator and thus the mass damper can be achieved.

[0011] The invention according to claim 3 is the pressure motor type mass damper according to claim 2, wherein the accumulator is arranged near the inlet and outlet of the housing, a manifold is attached to the inlet and outlet of the housing, and the drain pipe and the communication passage are connected to each other through the manifold.

[0012] According to this configuration, a manifold is attached to the inlet and outlet of the housing, and the drain pipe and the communication passage are connected through this manifold. Thereby, the length of the drain pipe is significantly shortened, so that further miniaturization and cost reduction of the accumulator can be achieved.

[0013] Also, in order to achieve the above object, the pressure motor type mass damper according to the invention of claim 4 includes a cylinder filled with a working fluid, a piston slidably provided in the cylinder and partitioning the inside of the cylinder into a first fluid chamber and a second fluid chamber, a communication passage bypassing the piston and communicating with the first and second fluid chambers, a housing having a drain passage communicating with the communication passage and for discharging the working fluid, and a rotating body housed in the housing, and a pressure motor that converts the flow of the working fluid accompanying the sliding of the piston into the rotational movement of the rotating body, a flywheel that is rotationally driven by the rotating body and exhibits a vibration damping effect, a tank chamber that stores the working fluid and can exchange the working fluid with the inside of the cylinder, and a drain pipe having one end communicating with the drain passage of the housing and the other end inserted into the tank chamber.

[0014] The mass damper of the present invention is a pressure motor type having the same basic configuration as the mass damper of claim 1. Therefore, similar to claim 1, as the piston in the cylinder slides, the working fluid is caused to flow in the communication passage and in the housing of the pressure motor, and the pressure of the working fluid due to the flow is converted into the rotational movement of the rotating body of the pressure motor, and the vibration damping effect is exhibited by rotationally driving the flywheel.

[0015] Further, the mass damper of the present invention includes a tank chamber that stores the working fluid and can exchange the working fluid with the inside of the cylinder, and one end of the drain pipe communicates with the drain passage of the housing and the other end is inserted into the tank chamber. With this configuration, for example, when the pressure of the working fluid in the housing rises, the working fluid in the housing can be directly discharged into the tank chamber to release the pressure, thereby reliably preventing excessive high pressure in the housing. Also, since the accumulator provided in claim 1 is omitted, further simplification of the configuration and cost reduction of the mass damper can be achieved.

[0016] Further, in order to achieve the above object, the pressure motor type mass damper according to the invention of claim 5 includes a cylinder filled with a working fluid, a piston slidably provided in the cylinder, partitioning the inside of the cylinder into a first fluid chamber and a second fluid chamber, and integrally having a piston rod penetrating the cylinder, a communication passage bypassing the piston and communicating with the first and second fluid chambers, a piston portion accumulator provided on the piston rod and having an accumulator chamber communicating with the first and second fluid chambers, for storing pressure when the working fluid in the first and second fluid chambers flows into the accumulator chamber, a housing communicating with the communication passage and having a drain passage for discharging the working fluid, and a rotating body accommodated in the housing, a pressure motor for converting the flow of the working fluid accompanying the sliding of the piston into the rotational movement of the rotating body, a flywheel rotationally driven by the rotating body and exhibiting a vibration damping effect, and a drain pipe having one end communicating with the drain passage of the housing and the other end communicating with the accumulator chamber of the piston portion accumulator, characterized by comprising the above.

[0017] The mass damper of the present invention is a pressure motor type having the same basic configuration as the mass damper of claim 1. Therefore, similar to claim 1, when the piston in the cylinder slides, the pressure when the working fluid flows in the communication passage and in the housing of the pressure motor is converted into the rotational movement of the rotating body of the pressure motor, and the vibration damping effect is exhibited by rotationally driving the flywheel. Further, in the mass damper of the present invention, a piston portion accumulator having an accumulator chamber is provided on the piston rod integral with the piston. The accumulator chamber communicates with the first and second fluid chambers, and when the pressure of the working fluid in the first and second fluid chambers rises, the pressure is stored by the working fluid flowing into the accumulator chamber. One end of the drain pipe communicates with the drain passage of the housing, and the other end communicates with the accumulator chamber.

[0018] With this configuration, when the pressure of the working fluid in the housing rises, the working fluid in the housing is discharged from the drain passage through the drain pipe into the accumulator chamber of the piston portion accumulator to release the pressure, thereby reliably preventing excessive high pressure in the housing. Further, a piston portion accumulator having an accumulator chamber as in the present invention is often provided in a pressure motor type mass damper in order to store the pressure increased due to temperature expansion of the working fluid or the like. Therefore, by omitting the accumulator on the pressure motor side provided in the mass damper of claim 1 and using the existing configuration in the piston portion as a drain accumulator, simplification and cost reduction of the configuration of the mass damper can be realized.

[0019] The invention according to claim 6 is characterized in that, in the pressure motor type mass damper according to claim 5, a check valve is further provided in the drain pipe, which allows only the flow of the working fluid from the drain passage side to the accumulator chamber side.

[0020] According to this configuration, when the pressure in the housing becomes greater than the pressure in the accumulator chamber, the check valve opens, allowing the pressure in the housing to escape to the accumulator chamber side and reliably maintaining it below the pressure in the accumulator chamber. Further, the pressure in the accumulator chamber is considerably smaller than the pressures in the first and second fluid chambers that increase as the piston moves. Therefore, compared with the case where a check valve is arranged in the drain pipe communicating with the first fluid chamber or the like, since the pressure acting on the check valve is very small, a great advantage is obtained that an inexpensive check valve with low pressure resistance performance can be used.

[0021] The invention according to claim 7 is characterized in that, in the pressure motor type mass damper according to claim 6, a drain tank chamber is further provided, which is connected to the drain passage and stores the working fluid flowing in from the housing through the drain passage.

[0022] According to this configuration, when the pressure of the working fluid in the housing increases, the working fluid in the housing flows into the drain tank chamber through the drain passage, and is accumulated in the drain tank chamber. As a result, combined with the pressure relief action of the check valve, the high pressure in the housing can be more reliably prevented.

[0023] Furthermore, in order to achieve the above object, the pressure motor type mass damper according to the invention of claim 8 includes a cylinder filled with a working fluid, a piston slidably provided in the cylinder and partitioning the inside of the cylinder into a first fluid chamber and a second fluid chamber, a communication passage bypassing the piston and communicating with the first and second fluid chambers, a housing having a drain passage communicating with the communication passage and for discharging the working fluid, and a rotating body accommodated in the housing, and a pressure motor that converts the flow of the working fluid accompanying the sliding of the piston into the rotational movement of the rotating body, a flywheel that is rotationally driven by the rotating body and exhibits a vibration suppression effect, a drain pipe that communicates with the communication passage and is connected to the drain passage for discharging the working fluid from the housing, and a switching valve provided in the drain pipe that operates in response to the reversal of the movement of the piston and switches the flow path of the working fluid so as to allow the flow from the drain passage in the drain pipe to the fluid chamber on the lower pressure side of the first and second fluid chambers.

[0024] The mass damper of the present invention is a pressure motor type having the same basic configuration as the mass damper of claim 1. Therefore, similar to claim 1, when the piston in the cylinder slides, the pressure when the working fluid flows in the communication passage and in the housing of the pressure motor is converted into the rotational movement of the rotating body of the pressure motor, and the flywheel is rotationally driven, thereby exhibiting a vibration suppression effect. Also, in the mass damper of the present invention, the drain pipe communicates with the communication passage and is connected to the drain passage.

[0025] Also, a switching valve provided in the drain pipe operates in response to the reversal of the movement of the piston, and switches the flow path of the working fluid so as to allow the flow from the drain passage in the drain pipe to the fluid chamber on the lower pressure side of the first and second fluid chambers. Thereby, when the pressure of the working fluid in the housing rises, the working fluid in the housing is discharged from the drain passage to the fluid chamber on the lower pressure side through the drain pipe and the communication passage, and the pressure is released, so that an excessive increase in pressure in the housing can be reliably prevented.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

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Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying out the Invention

[0027] Hereinafter, with reference to the drawings, preferred embodiments of the present invention will be described in detail. As shown in FIG. 1, a mass damper 1 according to a first embodiment of the present invention includes a horizontally extending cylinder 2, a piston 3 slidably provided in the cylinder 2, a communication passage 4 that bypasses the piston 3 and communicates with the inside of the cylinder 2, a gear motor 5 as a pressure motor disposed in the communication passage 4, a flywheel 9 connected to an output shaft 8 of the gear motor 5, an accumulator 21 attached to the gear motor 5, and the like.

[0028] The cylinder 2 integrally has a cylindrical peripheral wall 2a and first and second end walls 2b and 2c provided at both ends of the peripheral wall 2a. The internal space of the cylinder 2 is defined by these three walls 2a to 2c. A protruding portion 2d having a rod accommodating chamber 2g is concentrically and integrally provided on the first end wall 2b, and a first fixture FL1 is provided at its end via a universal joint.

[0029] The piston 3 is slidably provided in the cylinder 2 in the axial direction, and divides the internal space of the cylinder 2 into a first fluid chamber 2e and a second fluid chamber 2f. The first and second fluid chambers 2e and 2f and the communication passage 4 are filled with hydraulic oil HF. The hydraulic oil HF is a normal one having appropriate viscosity.

[0030] A piston rod 10 is concentrically and integrally provided on the piston 3. The piston rod 10 extends from both sides of the piston 3 in the axial direction. On the side of the second end wall 2c, it penetrates the rod guide hole in a liquid-tight manner and extends outward. A second fixture FL2 is provided at the outer end of the piston rod 10 via a universal joint. Also, on the side of the first end wall 2b, the piston rod 10 penetrates the rod guide hole in a liquid-tight manner and extends into the rod housing chamber 2g of the protrusion 2d, and a second accumulator 31 is provided at its end.

[0031] The second accumulator 31 is for storing pressure due to temperature expansion of the hydraulic oil HF, etc. It has a hollow casing portion 32 formed at the end of the piston rod 10, a piston 34 slidably provided in the casing portion 32 and defining an oil chamber 33 on the piston 3 side, and a set spring 35 for biasing the piston 34 toward the oil chamber 33 side. Also, a rod communication hole 10a is formed along the piston rod 10. The rod communication hole 10a communicates with the oil chamber 33 at one end and extends to the center of the piston 3 on the other end side.

[0032] On the other hand, the piston 3 is formed with first and second communication holes that penetrate in the axial direction and communicate with the first and second fluid chambers 2e, 2f, and a third communication hole that extends in the vertical direction to connect the first and second communication holes and communicates with the rod communication hole 10a. Check valves 36, 36 are provided on both sides of the third communication hole in the first communication hole. Each check valve 36 is configured to allow only the flow of the hydraulic oil HF from the third communication hole side to the first or second fluid chamber 2e, 2f side. Also, orifices 37, 37 are provided on both sides of the third communication hole in the second communication hole.

[0033] In the above configuration, when the pressure of the hydraulic fluid HF in the cylinder 2 increases due to an increase in the temperature of the hydraulic fluid HF or the like, the hydraulic fluid HF gently flows from the first and second fluid chambers 2e and 2f through the second communication hole of the piston 3, the orifices 37, 37, the third communication hole, and the rod communication hole 10a into the oil chamber 33 of the second accumulator 31. Along with this, the set spring 35 is compressed via the piston 34, so that the pressure of the hydraulic fluid HF is stored in the second accumulator 31, thereby avoiding problems caused by an increase in the pressure of the hydraulic fluid HF due to a temperature rise or the like.

[0034] From this state, when the temperature of the hydraulic fluid HF decreases, the hydraulic fluid HF in the oil chamber 33 returns to the first and second fluid chambers 2e and 2f through the rod communication hole 10a, the third communication hole, the opened check valves 36, 36, and the first communication path, thereby releasing the pressure stored in the second accumulator 31 and returning to the original state.

[0035] Also, the piston 3 is formed with a first relief communication path 3d and a second communication hole 3e that penetrate in the axial direction. A first relief valve 11 and a second relief valve 12 are respectively provided in the first and second communication paths 3d and 3e. The first and second relief valves 11 and 12 have the same configuration as each other and are configured as normally closed valves, and have a valve body and a spring that biases the valve body in the valve closing direction.

[0036] The first relief valve 11 closes the first communication path 3d until the pressure of the hydraulic fluid HF in the first fluid chamber 2e reaches a predetermined pressure, and opens the first communication path 3d when the predetermined pressure is reached. Thereby, the pressure in the first fluid chamber 2e is released to the second fluid chamber 2f side through the first communication path 3d and is limited to a predetermined pressure or less. Similarly, the second relief valve 12 closes the second communication path 3e until the pressure in the second fluid chamber 2f reaches a predetermined pressure, and opens the second communication path 3e when the predetermined pressure is reached. Thereby, the pressure in the second fluid chamber 2f is released to the first fluid chamber 2e side through the second communication path 3e and is limited to a predetermined pressure or less.

[0037] The gear motor 5 is, for example, an internal meshing type and is disposed at the center of the communication passage 4. The gear motor 5 includes a housing 6 that communicates with the communication passage 4 via two inlets / outlets 6a, 6a, a rotatable input gear and output gear (both not shown) that are accommodated in the housing 6 and mesh with each other, and an output shaft 8 that is integrally provided on the output gear. The housing 6 is supported by the peripheral wall 2a of the cylinder 2. Further, a drain passage (not shown) for discharging the hydraulic fluid HF is provided in the housing 6. The output shaft 8 is supported in a liquid-tight manner by the housing 6 via a seal (not shown). Note that, instead of the internal meshing type, an external meshing type may be used as the gear motor 5.

[0038] The flywheel 9 is made of a material having a relatively large specific gravity, such as a steel material, and is formed, for example, in a disc shape, and is integrally provided coaxially with the output shaft 8.

[0039] The accumulator 21 is for preventing the pressure in the housing 6 of the gear motor 5 from increasing by storing the pressure of the hydraulic fluid HF in the housing 6. The accumulator 21 is a spring type and is attached to the housing 6, and includes a casing 22 that communicates with the drain passage of the housing 6, a piston 24 that is slidably provided in the casing 22 and defines an oil chamber 23 on the housing 6 side, and a set spring 25 that biases the piston 24 toward the oil chamber 23 side.

[0040] Further, a drain pipe 27 is attached to the accumulator 21, and a check valve 28 for draining is provided in the drain pipe 27. The drain pipe 27 is connected to the oil chamber 23 of the accumulator 21 and a portion on the first fluid chamber 2e side of the communication passage 4. The check valve 28 is configured to allow only the flow of the hydraulic fluid HF from the accumulator 21 to the communication passage 4 side.

[0041] The mass damper 1 having the above configuration is attached, although not shown, between, for example, two relatively displaced portions (e.g., an upper beam and a lower beam) in a structure via the first and second fixtures FL1 and FL2 and is used as a seismic isolation device. Hereinafter, the operation of the mass damper 1 will be described.

[0042] First, when the structure is not vibrating, the mass damper 1 is in the initial state shown in FIG. 1, and the piston 3 is located at the center in the axial direction of the cylinder 2. From this initial state, when the structure vibrates during an earthquake or the like, the piston 3 moves within the cylinder 2 according to the relative displacement between two parts of the structure. Along with this, the hydraulic fluid HF in the first or second fluid chamber 2e, 2f is pushed out by the piston 3, flows into the communication passage 4, flows through the housing 6 of the gear motor 5, and then flows into the second or first fluid chamber 2f, 2e.

[0043] The pressure due to the flow of this hydraulic fluid HF is converted into the rotational motion of the input gear and output gear of the gear motor 5, and the flywheel 9 integrated with the output shaft 8 is rotationally driven, thereby exerting a rotational inertia mass effect (inertial force). In addition, a viscous damping effect (viscous force) due to the viscous resistance when the hydraulic fluid HF flows through the communication passage 4 and the like is exerted, and together with the rotational inertia mass effect, a vibration suppression effect of the structure is exerted.

[0044] Also, when the gear motor 5 operates in this way, as the pressure of the hydraulic fluid HF in the housing 6 increases, the hydraulic fluid HF flows into the oil chamber 23 of the accumulator 21 through the drain passage and compresses the set spring 25 via the piston 24. As a result, the pressure of the hydraulic fluid HF is stored in the accumulator 21, preventing the pressure in the housing 6 from increasing. Then, when the operation of the gear motor 5 ends, the hydraulic fluid HF in the oil chamber 23 returns to the housing 6 through the drain passage, releasing the pressure stored in the accumulator 21 and returning to the original state.

[0045] Furthermore, for example, when the mass damper 1 and the gear motor 5 operate for a long time along with the response of the structure due to the input of long-period seismic motion, the amount of the hydraulic fluid HF in the oil chamber 23 of the accumulator 21 may increase and approach a full state. In that case, as the pressure of the hydraulic fluid HF in the oil chamber 23 increases, the check valve 28 opens, and the hydraulic fluid HF in the oil chamber 23 is discharged into the first fluid chamber 2e via the drain pipe 27 and the communication passage 4. As a result, the accumulator 21 does not reach a full state, and the pressure accumulation function is maintained, thereby reliably preventing excessive high pressure in the housing 6. As a result, for example, the function of the seal of the output shaft 8 can be maintained and the life can be extended.

[0046] Note that even when the drain pipe 27 is arranged only on the side of the first fluid chamber 2e as in the embodiment, as the piston 3 reciprocates during vibration, the first fluid chamber 2e repeatedly becomes a high-pressure state and a low-pressure state, and the check valve 28 opens in the low-pressure state, so that the discharge of the hydraulic fluid HF from the oil chamber 23 to the first fluid chamber 2e can be reliably performed. Further, since the hydraulic fluid HF is appropriately discharged from the accumulator 21, the capacity of the accumulator 21 may be small. Thus, in combination with the one-sided arrangement of the drain pipe 27 as described above, miniaturization and cost reduction of the accumulator 21 and thus the mass damper 1 can be achieved. Of course, the drain pipe 27 may be provided only on the side of the second fluid chamber 2f, or may be provided on both sides of the first and second fluid chambers 2e and 2f.

[0047] FIG. 2 shows a mass damper 1A according to a modification of the first embodiment described above. In the figure, the same components as those of the mass damper 1 of the first embodiment are denoted by the same reference numerals. This mass damper 1A is obtained by changing the arrangement of the accumulator 21 and the configuration of the drain pipe 27 with respect to the mass damper 1.

[0048] Specifically, the accumulator 21 is disposed immediately above the inlet / outlet 6a on the first fluid chamber 2e side of the gear motor 5, and the oil chamber 23 communicates with the drain passage of the housing 6 via the L-shaped pipe 22a. On the other hand, a manifold (branch pipe) 29 communicating with the inside of the housing 6 is provided at the inlet / outlet 6a. A very short drain pipe 27A with a check valve 28 is connected to this manifold 29. Other configurations are the same as those of the first embodiment.

[0049] In this modification, similar to the first embodiment, the pressure of the hydraulic fluid HF in the housing 6 is stored in the accumulator 21, and the hydraulic fluid HF in the oil chamber 23 is allowed to escape into the first fluid chamber 2e through the drain pipe 27A with the check valve 28 and the communication passage 4, thereby maintaining the pressure accumulation function of the accumulator 21 and reliably preventing excessive high pressure in the housing 6. Further, compared with the first embodiment, since the length of the drain pipe 27A is significantly shortened, further miniaturization and cost reduction of the accumulator 21 can be achieved.

[0050] Next, the mass damper 51 according to the second embodiment of the present invention will be described with reference to FIG. 3. In the figure, the same or equivalent components as those of the mass damper 1 of the first embodiment described above are denoted by the same reference numerals. This mass damper 51 is different from the mass damper 1 of the first embodiment in that a piston rod is disposed only on one side of the piston, mainly to shorten the axial length for application to a seismic isolation device.

[0051] As shown in Fig. 3, the mass damper 51 includes a horizontally extending cylinder (inner tube) 52, an outer tube 81 outside the cylinder 52, a piston 53 slidably provided in the cylinder 52 and partitioning first and second fluid chambers 52e, 52f on both sides, a piston rod 60 integral with the piston 53, a communication passage 54 bypassing the piston 53 and communicating with the inside of the cylinder 52, a gear motor 5 disposed in the communication passage 54, a flywheel 9 connected to the output shaft 8 of the gear motor 5, an accumulator 21 attached to the gear motor 5, a drain pipe 27 with a check valve 28 connected to the accumulator 21 and the communication passage 54, and the like.

[0052] The outer tube 81 is provided so as to surround the cylinder 52, and a tank chamber 82 is defined between the peripheral walls 81a, 52a of the two and between one end walls 81c, 52c. In the tank chamber 82, hydraulic fluid HF is stored while leaving an air layer A at the uppermost part.

[0053] The piston rod 60 is provided only on the first fluid chamber 52e side from the piston 53, penetrates the other end walls 52b, 81b of the cylinder 52 and the outer tube 81 in a liquid-tight manner and extends outward, and a first fixture FL1 is provided at the outer end thereof. Also, a second fixture FL2 is provided on the end wall 81c on the opposite side of the outer tube 81.

[0054] Four communication passages penetrating in the axial direction are formed in the piston 53. A first pressure regulating valve 83, a first relief valve 84, a second pressure regulating valve 85, and a second relief valve 86 are respectively provided in these communication passages. All of these valves 83 to 86 are configured as normally closed valves and have a valve body for opening and closing the communication passage and a spring for biasing the valve body in the closing direction.

[0055] The first pressure regulating valve 83 opens when the pressure in the first fluid chamber 52e reaches the first predetermined pressure, and adjusts the pressure in the first fluid chamber 52e by allowing the hydraulic fluid HF to flow out to the second fluid chamber 52f side. The first relief valve 84 opens when the pressure in the first fluid chamber 52e reaches a second predetermined pressure higher than the first predetermined pressure, and limits the pressure in the first fluid chamber 52e to the second predetermined pressure or lower by allowing the hydraulic fluid HF to escape to the second fluid chamber 52f side.

[0056] Conversely, the second pressure regulating valve 85 opens when the pressure in the second fluid chamber 52f reaches the first predetermined pressure, and adjusts the pressure in the second fluid chamber 52f. The second relief valve 86 opens when the pressure in the second fluid chamber 52f reaches the second predetermined pressure, and limits the pressure in the second fluid chamber 52f to the second predetermined pressure or lower.

[0057] Also, on the end wall 52c of the cylinder 52, two communication passages are formed that penetrate in the axial direction and communicate with the second fluid chamber 52f and the tank chamber 82. In these communication passages, a third pressure regulating valve 87 and a third relief valve 88, which are configured in the same manner as the above-described valves 83 to 86, are provided. The third pressure regulating valve 87 opens when the pressure in the second fluid chamber 52f reaches the first predetermined pressure, and adjusts the pressure in the second fluid chamber 52f by allowing the hydraulic fluid HF to flow out to the tank chamber 82 side. The third relief valve 88 opens when the pressure in the second fluid chamber 52f reaches the second predetermined pressure, and limits the pressure in the second fluid chamber 52f to the second predetermined pressure or lower by allowing the hydraulic fluid HF to escape to the tank chamber 82 side.

[0058] Furthermore, two communication holes that penetrate in the axial direction are formed in the end wall 52c of the cylinder 52, and these communication holes are opened and closed by a check valve 89. The check valve 89 includes valve bodies 89a, 89a that open and close the communication holes, and a spring 89b that biases the valve body 89a toward the communication passage side, thereby allowing only the flow of the hydraulic fluid HF from the tank chamber 82 side to the second fluid chamber 52f side.

[0059] The other components of the mass damper 51, such as the gear motor 5, the flywheel 9, the accumulator 21, and the drain pipe 27 with the check valve 28, are configured in the same manner as the mass damper 1 of the first embodiment, except that the drain pipe 27 is arranged on the second fluid chamber 52f side.

[0060] The mass damper 51 with the above configuration is, although not shown in the drawings, attached between a structure and the ground via first and second fixtures FL1 and FL2, for example, and used as a seismic isolation device. The operation of the mass damper 51 will be described below.

[0061] First, when the structure is not vibrating, the mass damper 51 is in the initial state shown in FIG. 3. When the vibration of the ground is transmitted to the structure during an earthquake or the like from this initial state, the piston 53 moves within the cylinder 52 according to the relative displacement between the two.

[0062] For example, when the piston 53 moves to the first fluid chamber 52e side (when the piston rod 60 extends), the pressure in the first fluid chamber 52e increases due to being pressed by the piston 53, causing the first pressure regulating valve 83 to open. The hydraulic oil HF flows out to the second fluid chamber 52f side, and the hydraulic oil HF flows from the first fluid chamber 52e into the communication passage 54, flows through the housing 6 of the gear motor 5, and then returns to the second fluid chamber 52f. In this case, the insufficient amount of the hydraulic oil HF in the second fluid chamber 52f due to the difference in the cross-sectional areas between the first and second fluid chambers 52e and 52f according to the presence or absence of the piston rod 60 is replenished from the tank chamber 82 to the second fluid chamber 52f by the opening of the check valve 89.

[0063] On the other hand, when the piston 53 moves toward the second fluid chamber 52f (when the piston rod 60 contracts), the pressure in the second fluid chamber 52f increases due to being pressed by the piston 53. As a result, the second pressure regulating valve 85 opens, and the hydraulic fluid HF flows out toward the first fluid chamber 52e. At the same time, the hydraulic fluid HF flows from the second fluid chamber 52f into the communication passage 54, flows through the housing 6 of the gear motor 5, and then returns to the first fluid chamber 52e. In this case, the excess hydraulic fluid HF in the second fluid chamber 52f due to the difference in cross-sectional area between the first and second fluid chambers 52e and 52f is discharged from the second fluid chamber 52f to the tank chamber 82 when the third pressure regulating valve 87 opens.

[0064] Then, as the structure vibrates, the pressure of the hydraulic fluid HF flowing through the communication passage 54 as described above is converted into the rotational motion of the gear motor 5, and the flywheel 9 integrated with the output shaft 8 is rotationally driven, thereby exerting the rotational inertia mass effect (inertial force). In addition, the viscous damping effect (viscous force) due to the viscous resistance when the hydraulic fluid HF flows through the communication passage 54 and the like is exerted, and together with the rotational inertia mass effect, the vibration suppression effect of the structure is exerted.

[0065] Also, when the gear motor 5 operates, as the pressure of the hydraulic fluid HF in the housing 6 increases, the hydraulic fluid HF flows into the oil chamber 23 of the accumulator 21 through the drain passage, so that the pressure of the hydraulic fluid HF is stored in the accumulator 21 and the high pressure in the housing 6 is prevented.

[0066] Furthermore, for example, when the mass damper 1 and the gear motor 5 operate for a long time due to the response of the structure to long-period seismic input, etc., and the amount and pressure of the hydraulic fluid HF in the oil chamber 23 of the accumulator 21 increase, the check valve 28 opens, and the hydraulic fluid HF in the oil chamber 23 is discharged to the second fluid chamber 52f through the drain pipe 27 and the communication passage 54. As a result, the accumulator 21 does not become full, and the pressure accumulation function is maintained, so that the high pressure in the housing 6 can be surely prevented. As a result, for example, the function of the seal of the output shaft 8 can be maintained and the life can be extended.

[0067] Further, since the drain pipe 27 is arranged only on the second fluid chamber 52f side and the capacity of the accumulator 21 may be small, the accumulator 21 and thus the mass damper 51 can be reduced in size and cost. Note that the drain pipe 27 may be provided only on the first fluid chamber 52e side, or may be provided on both sides of the first and second fluid chambers 52e and 52f.

[0068] FIG. 4 shows a mass damper 51A according to a modification of the second embodiment described above. In the figure, the same components as those of the mass damper 51 of the second embodiment are denoted by the same reference numerals. This mass damper 51A is obtained by omitting the accumulator 21 from the mass damper 51, connecting one end of the drain pipe 27 with a check valve 28 to the drain passage of the housing 6 of the gear motor 5, and inserting the other end into the tank chamber 82. Other configurations are the same as those of the first embodiment.

[0069] In this modification, when the pressure of the hydraulic oil HF in the housing 6 increases with the operation of the gear motor 5, the hydraulic oil HF is discharged into the tank chamber 82 in the atmospheric state through the drain pipe 27 and the opened check valve 28, and the high pressure in the housing 6 is prevented. Thus, since the functions required for the accumulator 21 in the first and second embodiments are obtained, further simplification of the configuration and cost reduction of the mass damper can be achieved by omitting the accumulator.

[0070] Next, the mass damper 101 according to the third embodiment of the present invention will be described with reference to FIG. 5. As is clear from the comparison with FIG. 1, this mass damper 101 is obtained by omitting the accumulator 21 on the gear motor 5 side from the mass damper 1 of the first embodiment, connecting one end of the drain pipe 102 to the housing 6 of the gear motor 5, and connecting the other end to the second accumulator 31 provided on the piston rod 10. Other configurations are the same as those of the first embodiment.

[0071] As already described in connection with the first embodiment, the second accumulator 31 is for storing the pressure due to the thermal expansion of the hydraulic fluid HF or the like, and has a casing portion 32 formed at the end of the piston rod 10, a piston 34 and a set spring 35 disposed in the oil chamber 33 of the casing portion 32. The oil chamber 33 communicates with the first and second fluid chambers 2e, 2f via the rod communication hole 10a of the piston rod 10 and a plurality of communication holes of the piston 3 provided with check valves 36 and orifices 37.

[0072] In the above configuration, when the pressure of the hydraulic fluid HF in the cylinder 2 increases with an increase in the temperature of the hydraulic fluid HF or the like, the hydraulic fluid HF gently flows from the first and second fluid chambers 2e, 2f into the oil chamber 33 through the communication holes of the piston 3, the orifices 37, 37 and the rod communication hole 10a. Along with this, the set spring 35 is compressed via the piston 34, so that the pressure of the hydraulic fluid HF is stored in the second accumulator 31, thereby avoiding problems caused by an increase in the pressure of the hydraulic fluid HF due to a temperature rise or the like.

[0073] One end of the drain pipe 102 communicates with a drain passage (not shown) of the housing 6 of the gear motor 5, penetrates the protruding portion 2d of the cylinder 2, the casing portion 32 of the second accumulator 31 and the piston 34, and communicates with the oil chamber 33 at the other end.

[0074] With this configuration, when the pressure of the hydraulic fluid HF in the housing 6 increases, the hydraulic fluid HF in the housing 6 is discharged from the drain passage through the drain pipe 102 into the oil chamber 33 of the second accumulator 31 to release the pressure, thereby reliably preventing excessive high pressure in the housing 6. Further, by omitting the accumulator 21 on the gear motor 5 side provided in the mass damper 1 of the first embodiment and using the existing accumulator provided on the piston rod 10 for dealing with the thermal expansion of the hydraulic fluid HF or the like as a drain accumulator, simplification of the configuration and cost reduction of the mass damper can be achieved.

[0075] FIG. 6 shows a mass damper 101A according to the first modification of the above-described third embodiment. This mass damper 101A is obtained by providing a check valve 103 in the drain pipe 102 of the mass damper 101 of the third embodiment. The check valve 103 is configured to allow only the flow of the hydraulic fluid HF from the drain passage side to the oil chamber 33 side of the second accumulator 31.

[0076] In this first modification, when the pressure in the housing 6 becomes higher than the pressure in the oil chamber 33, the check valve 103 opens, allowing the pressure in the housing 6 to escape to the oil chamber 33 side and ensuring that it is maintained below the pressure in the oil chamber 33. Further, the pressure in the oil chamber 33 is considerably lower than the pressures in the first and second fluid chambers 2e and 2f that increase as the piston 3 moves. Therefore, compared with the mass damper 1 of the first embodiment in which the check valve 28 is disposed in the drain pipe 27 communicating with the first fluid chamber 2e, the pressure acting on the check valve 103 is very small, and thus a great advantage is obtained in that an inexpensive check valve with low pressure resistance can be used.

[0077] FIG. 7 shows a mass damper 101B according to the second modification of the third embodiment. This mass damper 101B is obtained by adding a drain tank chamber 104 to the mass damper 101A of the above-described first modification. The drain tank chamber 104 is connected to a drain passage (not shown) and is configured to store the hydraulic fluid HF flowing in from the housing 6 through the drain passage.

[0078] In this second modification, when the pressure of the hydraulic fluid HF in the housing 6 rises, the hydraulic fluid HF in the housing 6 flows into the drain tank chamber 104 through the drain passage and is accumulated in the drain tank chamber 104. Thereby, in combination with the pressure relief action by the check valve 103, it is possible to more reliably prevent the pressure in the housing 6 from increasing.

[0079] Next, with reference to FIG. 8, the mass damper 151 according to the fourth embodiment of the present invention will be described. As is clear from the comparison with FIG. 1, this mass damper 151 omits the accumulator 21 on the side of the gear motor 5 with respect to the mass damper 1 in the first embodiment, and includes a drain pipe 152 connected in parallel to the communication passage 4, a pair of on-off valves 153, 153 provided in the drain pipe 152, and the like.

[0080] The drain pipe 152 is connected to a drain passage (not shown) of the housing 6 at the central portion and is connected to the communication passage 4 at both end portions. The on-off valves 153 are arranged on both sides of the connection portion of the drain pipe 152 with the drain passage, and an orifice 154 is provided outside thereof. Each on-off valve 153 is of a normally open type, extends in the vertical direction, and includes a cylindrical casing 155 communicating with the drain pipe 152, a valve body 156 slidably provided in the casing 155 in the vertical direction, and a return spring 157 that biases the valve body 156 toward the valve opening side (downward in the figure). A pressure introduction pipe 158 branched from the communication passage 4 side of the drain pipe 152 is connected to the lower end portion of the casing 155.

[0081] In the above configuration, as the structure vibrates, when the piston 3 moves in one direction, for example, as indicated by the arrow in FIG. 9, toward the second fluid chamber 2f side, the hydraulic oil HF in the second fluid chamber 2f is pushed out by the piston 3 and flows into the communication passage 4. By rotating the gear motor 5, the vibration suppression effect of the structure is exerted from the rotational inertia mass effect of the flywheel 9 and the viscous damping effect of the viscous resistance of the hydraulic oil HF.

[0082] Also, in this state, the pressure of the second fluid chamber 2f pressurized by the piston 3 is introduced from the communication passage 4 through the pressure introduction pipe 158 to the lower end portion of the casing 155 of the right on-off valve 153. As a result, the valve body 156 is pushed up against the spring force of the return spring 157, and the on-off valve 153 closes, thereby blocking the flow of the hydraulic oil HF from the high-pressure side to the drain passage side in the drain pipe 152.

[0083] On the one hand, in this state, since the left on-off valve 153 is open, when the pressure of the hydraulic fluid HF in the housing 6 rises, the hydraulic fluid HF is discharged from the drain passage to the first fluid chamber 2e on the low-pressure side through the drain pipe 152, the on-off valve 153, and the communication passage 4, and the pressure is released. Thereby, excessive high pressure in the housing 6 can be reliably prevented.

[0084] Although not shown, when the piston 3 moves to the first fluid chamber 2e side, the operation opposite to the above is obtained. Thereby, when the left on-off valve 153 closes, the flow of the hydraulic fluid HF from the high-pressure side to the drain passage side in the drain pipe 152 is blocked, and when the pressure of the hydraulic fluid HF in the housing 6 rises, the hydraulic fluid HF is discharged from the drain passage to the second fluid chamber 2f on the low-pressure side through the open right on-off valve 153 and the like, and the pressure is released. In addition, although the orifice 154 provided in parallel with the on-off valve 153 is not essential, it has the advantage of making the operation (opening and closing) of the on-off valve 153 smoother by causing a pressure loss.

[0085] FIG. 10 shows a mass damper 151A according to the first modification of the fourth embodiment. This mass damper 151A is obtained by adding a drain tank chamber 159 to the mass damper 151 of the above fourth embodiment. The drain tank chamber 159 is connected to a drain passage (not shown) of the housing 6.

[0086] In this first modification, when the pressure of the hydraulic fluid HF in the housing 6 rises, the hydraulic fluid HF in the housing 6 flows into the drain tank chamber 159 through the drain passage and is stored, whereby it is accumulated in the drain tank chamber 159. Thereby, combined with the pressure release action to the low-pressure side by the drain pipe 152, the high pressure in the housing 6 can be more reliably prevented.

[0087] FIG. 11 shows a mass damper 151B according to a second modification of the fourth embodiment. This mass damper 151B is provided with a drain pipe 152, an on-off valve 153, and an orifice 154 only on the first fluid chamber 2e side, omitting them on the second fluid chamber 2f side with respect to the mass damper 151A of the above-described first modification. The drain tank chamber 159 is connected to a drain passage (not shown) of the housing 6.

[0088] In this second modification, when the piston 3 moves to the first fluid chamber 2e side, the pressure of the first fluid chamber 2e pressurized by the piston 3 is introduced into the casing 155 of the on-off valve 153, and the on-off valve 153 closes, thereby blocking the flow of the hydraulic oil HF from the high-pressure side to the drain passage side in the drain pipe 152. On the other hand, when the pressure of the hydraulic oil HF in the housing 6 rises at the timing when the piston 3 moves to the second fluid chamber 2f side, the hydraulic oil HF is discharged from the drain passage to the first fluid chamber 2e on the low-pressure side through the on-off valve 153 in the open valve state and the like. As a result, combined with the pressure accumulation action of the drain tank chamber 159, it is possible to reliably prevent the pressure in the housing 6 from increasing.

[0089] FIGS. 12 and 13 show a mass damper 151C according to a third modification of the fourth embodiment. This mass damper 151C is provided with a spool valve 161 as a switching valve instead of the pair of on-off valves 153 and orifices 154 in the mass damper 151 of the fourth embodiment.

[0090] The spool valve 161 is arranged one above the gear motor 5 and has a cylindrical casing 162 extending in the left - right direction and a valve body 163 slidably provided in the left - right direction within the casing 162. The casing 162 communicates with the drain pipe 152 at both ends and communicates with a drain passage (not shown) of the housing 6 at the central portion. The valve body 163 has a string - like shape integrally having a shaft portion and first and second land portions on its left and right sides. The first and second land portions are in sliding contact with the peripheral wall of the casing 162, and an oil chamber 164 communicating with the drain passage is defined between the shaft portion and the peripheral wall of the casing 162. Also, first and second bypass pipes 165a, 165b are provided which bypass the first and second land portions respectively and communicate with the drain pipe 152 and the oil chamber 164.

[0091] In the above - described configuration, as the structure vibrates, when the piston 3 moves toward the first fluid chamber 2e as indicated by the arrow in FIG. 12, the hydraulic fluid HF in the first fluid chamber 2e is pushed out by the piston 3 and flows into the communication passage 4. By rotating the gear motor 5, the vibration suppression effect of the structure is exerted from the rotational inertia mass effect by the flywheel 9 and the viscous damping effect by the viscous resistance of the hydraulic fluid HF.

[0092] Also, in this state, the pressure of the first fluid chamber 2e pressurized by the piston 3 acts on the valve body 163 from the communication passage 4 through the drain pipe 152, and thus the valve body 163 is driven to the right in the figure. As a result, the first land portion of the valve body 163 closes the first bypass pipe 165a, thereby blocking the flow of the hydraulic fluid HF from the high - pressure side to the low - pressure side or the drain passage side in the drain pipe 152.

[0093] On the one hand, in this state, since the drain passage communicates with the oil chamber 164 of the spool valve 161 and the oil chamber 164 communicates with the second bypass pipe 165b, when the pressure of the hydraulic fluid HF in the housing 6 rises, the hydraulic fluid HF is discharged from the drain passage to the second fluid chamber 2f on the low-pressure side through the oil chamber 164, the second bypass pipe 165b, the drain pipe 152, and the communication passage 4, and the pressure is released. Thereby, excessive high pressure in the housing 6 can be reliably prevented.

[0094] On the contrary, when the piston 3 moves toward the second fluid chamber 2f as indicated by the arrow in FIG. 13, the valve body 163 of the spool valve 161 is driven to the left in the figure, and thus an operation opposite to that in the case of FIG. 12 is obtained. That is, when the second land portion of the valve body 163 closes the second bypass pipe 165b, the flow of the hydraulic fluid HF from the high-pressure side to the low-pressure side or the drain passage side in the drain pipe 152 is blocked. Further, since the drain passage communicates with the oil chamber 164 and the oil chamber 164 communicates with the first bypass pipe 165a, when the pressure of the hydraulic fluid HF in the housing 6 rises, the hydraulic fluid HF is discharged from the drain passage to the first fluid chamber 2e on the low-pressure side through the oil chamber 164, the first bypass pipe 165a, the drain pipe 152, and the communication passage 4, and the pressure is released.

[0095] Note that the present invention is not limited to the described embodiments and modifications, and can be implemented in various modes. For example, in the first and second embodiments, a check valve 28 that allows only the flow of the hydraulic fluid HF from the accumulator 21 to the communication passage 4 (54) side is provided in the drain pipe 27. However, instead of the check valve 28, a relief valve having a predetermined opening pressure smaller than the set pressure of the accumulator 21 may be provided.

[0096] Further, in the modification of the second embodiment, the hydraulic fluid HF in the housing 6 with increased pressure is configured to be released to the tank chamber 82 through the drain pipe 27 with the check valve 28. However, as long as the tank chamber 82 is maintained in the atmospheric state, the check valve 28 may be omitted, and in that case as well, the hydraulic fluid HF can be reliably released to the tank chamber 82.

[0097] Furthermore, in the embodiment, a gear motor is used as the pressure motor, but other types of pressure motors, such as piston motors, vane motors, and screw motors, may also be used. Also, in the embodiment, it has been described that normal hydraulic fluid HF is used as the working fluid of the damper, but of course, other suitable working fluids may be used.

[0098] Also, as the accumulator, in the first and second embodiments, a spring-type accumulator having a piston and a set spring is used. However, as long as it has a function of storing the pressure of the working fluid, its type is arbitrary. For example, accumulators such as bladder type and diaphragm type, or a pressure-relief tank type accumulator (utilizing an air spring) in which the piston and the set spring, which are components of the accumulators in the first and second embodiments, are removed and the air layer is sealed can be used.

[0099] Also, in the fourth embodiment, a pair of on-off valves 153, 153 or a spool valve 161 is exemplified as the switching valve. However, any configuration can be adopted as long as it operates in response to the reversal of the movement of the piston and switches the flow path of the working fluid so as to allow the flow from the drain passage in the drain pipe to the low-pressure side fluid chamber. In addition, the detailed configuration can be appropriately changed within the scope of the gist of the present invention.

Explanation of Reference Numerals

[0100] 1 Mass damper according to the first embodiment 1A Mass damper according to a modification of the first embodiment 2 Cylinder 2e First fluid chamber 2f Second fluid chamber 3 Piston 4 Communication passage 5 Gear motor (pressure motor) 6 Housing 6a Inlet / outlet of the housing 8 Output shaft (rotating body) 9 Flywheel 10 Piston rod 21 Accumulator 27 Drain pipe 27A Drain pipe 28 Check valve (on-off valve) 29 Manifold 31 Second accumulator (piston part accumulator) 33 Oil chamber (accumulation pressure chamber) 51 Mass damper according to the second embodiment 51A Mass damper according to a modification of the second embodiment 52 Cylinder 52e First fluid chamber 52f Second fluid chamber 53 Piston 54 Communication passage 82 Tank chamber 101 Mass damper according to the third embodiment 101A Mass damper according to the first modification of the third embodiment 101B Mass damper according to the second modification of the third embodiment 102 Drain pipe 103 Check valve 104 Drain tank chamber 151 Mass damper according to the fourth embodiment 151A Mass damper according to the first modification of the fourth embodiment 151B Mass damper according to the second modification of the fourth embodiment 151C Mass damper according to the third modification of the fourth embodiment 152 Drain pipe 153 On-off valve (changeover valve) 161 Spool valve (changeover valve) HF Hydraulic oil (working fluid)

Claims

1. A cylinder filled with a working fluid, a piston slidably provided in the cylinder and partitioning the inside of the cylinder into a first fluid chamber and a second fluid chamber, a communication passage bypassing the piston and communicating with the first and second fluid chambers, a housing having a drain passage communicating with the communication passage and for discharging the working fluid, and a rotating body accommodated in the housing, and a pressure motor for converting the flow of the working fluid accompanying the sliding of the piston into the rotational movement of the rotating body, a flywheel rotatably driven by the rotating body and exhibiting a vibration damping effect, an accumulator for storing pressure when the working fluid in the housing flows in, a drain pipe connected to the accumulator and the communication passage for discharging the working fluid from the accumulator to the first and / or second fluid chambers, and provided with an on-off valve for allowing the flow of the working fluid from the accumulator to the communication passage side, A pressure motor type mass damper characterized by comprising the above.

2. The pressure motor type mass damper according to claim 1, wherein the drain pipe is connected to one side of the first fluid chamber and the second fluid chamber of the communication passage.

3. The accumulator is disposed near the inlet and outlet of the housing, a manifold is attached to the inlet and outlet of the housing, The pressure motor type mass damper according to claim 2, wherein the drain pipe and the communication passage are connected to each other via the manifold.

4. A cylinder filled with a working fluid, a piston slidably provided in the cylinder and partitioning the inside of the cylinder into a first fluid chamber and a second fluid chamber, a communication passage bypassing the piston and communicating with the first and second fluid chambers, a housing having a drain passage communicating with the communication passage and for discharging the working fluid, and a rotating body accommodated in the housing, and a pressure motor for converting the flow of the working fluid accompanying the sliding of the piston into the rotational movement of the rotating body, a flywheel rotatably driven by the rotating body and exhibiting a vibration damping effect, a tank chamber for storing the working fluid and capable of exchanging the working fluid with the inside of the cylinder, a drain pipe having one end communicating with the drain passage and the other end inserted into the tank chamber for discharging the working fluid from the housing. A pressure motor type mass damper characterized by comprising **Claim 5** A cylinder filled with a working fluid, A piston slidably provided in the cylinder, partitioning the inside of the cylinder into a first fluid chamber and a second fluid chamber, and integrally having a piston rod penetrating the cylinder, A communication passage bypassing the piston and communicating with the first and second fluid chambers, A piston portion accumulator provided on the piston rod, having an accumulator chamber communicating with the first and second fluid chambers, and storing pressure when the working fluid in the first and second fluid chambers flows into the accumulator chamber, A housing having a drain passage for discharging the working fluid while communicating with the communication passage, and a rotating body accommodated in the housing, and a pressure motor for converting the flow of the working fluid accompanying the sliding of the piston into the rotational movement of the rotating body, A flywheel rotated by the rotating body and exhibiting a vibration damping effect, A drain pipe having one end communicating with the drain passage and the other end communicating with the accumulator chamber of the piston portion accumulator for discharging the working fluid from the housing, A pressure motor type mass damper characterized by comprising **Claim 6** The pressure motor type mass damper according to claim 5, further comprising a check valve provided in the drain pipe and allowing only the flow of the working fluid from the drain passage side to the accumulator chamber side. **Claim 7** The pressure motor type mass damper according to claim 6, further comprising a drain tank chamber connected to the drain passage and storing the working fluid flowing into the housing through the drain passage. **Claim 8** A cylinder filled with a working fluid, A piston slidably provided in the cylinder and partitioning the inside of the cylinder into a first fluid chamber and a second fluid chamber, A communication passage bypassing the piston and communicating with the first and second fluid chambers, A housing having a drain passage for discharging the working fluid while communicating with the communication passage, and a rotating body accommodated in the housing, and a pressure motor for converting the flow of the working fluid accompanying the sliding of the piston into the rotational movement of the rotating body, A flywheel rotated by the rotating body and exhibiting a vibration damping effect, A drain pipe communicating with the communication passage and connected to the drain passage for discharging the working fluid from the housing, A switching valve provided in the drain pipe, operating in response to the reversal of the movement of the piston, and switching the flow path of the working fluid so as to allow the flow from the drain passage in the drain pipe to the fluid chamber on the lower pressure side of the first and second fluid chambers. A pressure motor type mass damper characterized by comprising the same.

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