Mass damper using pressure motor

Abstract

To provide a mass damper using a pressure motor which enables improvement of assemblability of a drain piping which discharges a working fluid from a housing of the pressure motor and can prevent damage caused by bending.SOLUTION: A mass damper 1 of the invention includes: a gear motor 5 which has a housing 6 provided at a communication passage 4 communicating with first and second fluid chambers 2f, 2g of a cylinder 2 and is configured to convert flow of a working fluid HF into rotational motion; an accumulator 21 which is provided at a piston rod 10 and accumulates a pressure by the working fluid HF in the first and second fluid chambers 2f, 2g flowing into a pressure accumulation chamber 23; an accumulator passage 29 which is open on a surface of a portion of the piston rod 10 protruding from the cylinder 2 and communicates with the pressure accumulation chamber 23; and a flexible drain hose 31 which communicates with a drain passage of the housing 6 to discharge the working fluid HF from the housing 6 and is connected to an opening 29c of the accumulator passage 29 in a loose state.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a mass damper that uses a pressure motor to convert the pressure of a working fluid generated in association with vibration of a structure into rotational motion of a rotating mass in order to suppress vibration of the structure or the like. [Background technology]

[0002] As such a conventional pressure motor type mass damper, for example, a hydraulic motor type disclosed in Patent Document 1 is known. In this mass damper, the hydraulic motor is accommodated in a housing and has a drain passage for discharging hydraulic oil, and an accumulator is connected to the drain passage. When the pressure inside the housing rises during operation of the mass damper, the pressure is transmitted to the accumulator via the drain passage and stored therein. This prevents the pressure inside the housing from becoming too high, maintains the sealing function of the output shaft of the hydraulic motor, and extends the life of the hydraulic motor.

[0003] Furthermore, in a mass damper of this configuration, when it operates for a long period of time, for example in response to the input of long-period seismic motion, the accumulator may become filled with hydraulic oil, making it unable to perform any further pressure accumulation function, and the pressure inside the housing may increase, causing problems such as hydraulic oil leaking from the sealed portion of the output shaft.

[0004] The present applicant has focused on such a defect and has already filed a pressure motor type mass damper to solve this problem (for example, Japanese Patent Application No. 2022-63924). As shown in FIG. 7, this mass damper 101 is a gear motor type, and one end of a drain pipe 102 is connected to a housing 104 of a gear motor 103, and the other end is connected to an accumulator 107 provided on a piston rod 106 integral with a piston 105. The accumulator 107 is for storing the pressure increased due to the expansion of the hydraulic oil HF due to the temperature rise, and has a casing part 109 formed at the end of the piston rod 106 and disposed in a hollow cylinder protruding part 108a protruding from the cylinder 108, and a piston 111 and a set spring 112 disposed in an oil chamber 110 of the casing part 109. The oil chamber 110 communicates with first and second fluid chambers 108b, 108c of the cylinder 108 via the rod communication hole 106a of the piston rod 106. One end of the drain pipe 102 communicates with a drain passage (not shown) of the housing 104, passes through a hole 108d of the cylinder protrusion 108a, and is connected to the piston 111 of the accumulator 107 at the other end, and communicates with the oil chamber 110.

[0005] In the above configuration, when the pressure of the hydraulic oil HF in the cylinder 108 increases due to expansion caused by a rise in temperature of the hydraulic oil HF, the hydraulic oil HF flows from the first and second fluid chambers 108b, 108c through the communication hole of the piston 105 and the rod communication hole 106a into the oil chamber 110 of the accumulator 107. As a result, the piston 111 moves and compresses the set spring 112, so that the pressure of the hydraulic oil HF is stored in the accumulator 107 and an increase in pressure is prevented.

[0006] In addition, when the pressure of the hydraulic oil HF in the housing 104 increases due to the operation of the mass damper 101, the hydraulic oil HF in the housing 104 is discharged from the drain passage through the drain piping 102 to the oil chamber 110 of the accumulator 107, and the pressure is released, thereby preventing the pressure in the housing 104 from increasing. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2020-94680 A Summary of the Invention [Problem to be solved by the invention]

[0008] In the mass damper 101 by the present applicant described above, the drain pipe 102 passes through the hole 108d in the cylinder protrusion 108a and is connected to the piston 111 of the accumulator 107. Therefore, the portion from these passing parts to the connection part needs to follow the movement of the piston 111 relative to the cylinder 108 (the sum of the movement of the piston rod 106 accompanying the operation of the mass damper 101 and the movement of the piston 111 accompanying the operation of the accumulator 107).

[0009] For this reason, in this mass damper 101, the drain pipe 102 is actually configured with a flexible drain hose, and is attached in a loosened state inside the cylinder protruding portion 108a. The attachment of this drain hose must be performed, for example, by passing the drain hose through a hole 108d in the cylinder protruding portion 108a, and inserting the tip of the drain hose into the casing portion 109 and the piston 111 in a loosened state inside the cylinder protruding portion 108a, which is not an easy task.

[0010] Even if the drain hose is attached in a loose state inside cylinder protrusion 108a as described above, the drain hose may bend and break due to repeated pushing and pulling (expanding and contracting) in the narrow space inside cylinder protrusion 108a as mass damper 101 and accumulator 107 operate, resulting in a risk of malfunction such as leakage of hydraulic oil HF. Furthermore, this portion of the drain hose is inside cylinder protrusion 108a and cannot be seen from the outside, so even if a malfunction such as damage to the drain hose or leakage of hydraulic oil HF occurs, the situation cannot be easily grasped.

[0011] The present invention has been made to solve the above-mentioned problems, and has an object to provide a mass damper using a pressure motor that improves the assemblyability of a drain pipe that discharges working fluid to prevent high pressure inside the housing of the pressure motor, and that can prevent damage due to bending of the drain pipe and the resulting leakage of working fluid. [Means for solving the problem]

[0012] In order to achieve this object, a mass damper using a pressure motor according to the invention of claim 1 comprises a cylinder filled with a working fluid, a piston slidably provided within the cylinder and dividing the interior of the cylinder into a first fluid chamber and a second fluid chamber, a piston rod integral with the piston, extending in the axial direction and partially projecting outside the cylinder, a communication passage bypassing the piston and communicating with the first and second fluid chambers, and a pressure accumulator provided in the piston rod and communicating with the first and second fluid chambers, and the working fluid in the first and second fluid chambers flows into the pressure accumulator, and an accumulator communicating with the communication passage and operating The pressure motor has a housing having a drain passage for discharging the working fluid, and a rotor accommodated in the housing, and converts the flow of the working fluid caused by the sliding of the piston into rotational motion of the rotor; a flywheel that is rotationally driven by the rotor and exhibits a vibration suppression effect; an accumulator passage that opens at one end on the surface of a part of the piston rod that protrudes from the cylinder and communicates with the pressure accumulation chamber of the accumulator at the other end; and a flexible drain hose that communicates with the drain passage and is connected in a loose state to the opening of the accumulator passage in order to discharge the working fluid from the housing.

[0013] The mass damper of the present invention uses a pressure motor, and as the piston slides in the cylinder, the working fluid flows from the first or second fluid chamber to a communication passage and a housing of the pressure motor, and the pressure of the working fluid caused by the flow is converted into the rotational motion of the rotor of the pressure motor to rotate the flywheel, thereby exerting a vibration suppression effect. Also, an accumulator having a pressure accumulator chamber communicating with the first and second fluid chambers is provided on the piston rod integral with the piston. When the pressure in the first and second fluid chambers rises due to a rise in temperature of the working fluid, the working fluid flows into the pressure accumulator chamber, and a part of the pressure in the first and second fluid chambers is accumulated in the pressure accumulator chamber.

[0014] Furthermore, the drain passage of the housing of the pressure motor is connected to the pressure accumulator of the accumulator through a drain hose and an accumulator passage. When the pressure in the housing rises, the working fluid in the housing is discharged from the drain passage through the drain hose and the accumulator passage to the pressure accumulator, thereby releasing the pressure and preventing the pressure in the housing from increasing.

[0015] According to the present invention, the drain hose is flexible, the accumulator passage opens into the surface of the portion of the piston rod that protrudes from the cylinder, the drain hose communicates with the drain passage and is connected in a loose state to the opening of the accumulator passage. With this configuration, the drain hose can smoothly follow the relative movement of the piston rod with respect to the housing during operation of the mass damper, and even when repeatedly pushed and pulled, damage due to bending and resulting problems such as leakage of working fluid can be prevented.

[0016] In addition, since the drain hose is disposed on the outside of the piston rod and can be seen from the outside, if any malfunction such as damage or leakage of the working fluid occurs, the situation can be easily grasped. Furthermore, unlike the mass damper shown in Fig. 7, the drain hose can be easily attached by simply connecting it from the outside to the opening of the accumulator passage formed on the surface of the piston rod, which improves the ease of assembly.

[0017] The invention according to claim 2 is characterized in that, in the mass damper using the pressure motor according to claim 1, the piston rod has a first rod portion extending from the piston to one side in the axial direction and partially protruding outside the cylinder, and a second rod portion extending from the piston to the other side in the axial direction, housed in the cylinder, and provided with an accumulator, the accumulator passage has a first passage portion opening at a surface of the first rod portion and extending inward, and a second passage portion connected to an inner end of the first passage portion, penetrating the first rod portion, the piston, and the second rod portion, extending in the axial direction, and communicating with the accumulator chamber, and the drain hose is connected to the opening of the first passage portion.

[0018] In this configuration, the piston rod has a first rod portion and a second rod portion extending from the piston to one side and the other side in the axial direction, respectively, the first rod portion partially protruding outside the cylinder, the second rod portion being housed in the cylinder, and an accumulator is provided. The accumulator passage has a first passage portion opening on a surface of the first rod portion, and a second passage portion connected to an inner end of the first passage portion, penetrating the first rod portion, the piston, and the second rod portion, and communicating with the accumulator chamber, and the drain hose is connected to the opening of the first passage portion.

[0019] According to this configuration, when the pressure inside the housing rises, the working fluid inside the housing is discharged from the drain passage through the drain hose, the first passage portion, and the second passage portion penetrating the first rod portion, the piston, and the second rod portion into the pressure accumulation chamber of the accumulator, thereby preventing the housing from becoming over-pressurized. Also, the drain hose and the accumulator passage are configured to satisfy the conditions of claim 1, and therefore, the effects of claim 1 described above can be obtained, such as preventing problems such as damage to the drain hose and resulting leakage of the working fluid, and improving the ease of assembly of the drain hose.

[0020] The invention according to claim 3 is characterized in that the mass damper using the pressure motor according to claim 1 or 2 further includes a check valve provided in the drain hose to allow only the flow of working fluid from the housing side to the accumulator side.

[0021] According to this configuration, when the pressure inside the housing becomes greater than the pressure in the pressure accumulator, the check valve opens, thereby releasing the pressure inside the housing to the pressure accumulator and maintaining the pressure below the pressure accumulator, thereby reliably preventing the pressure inside the housing from increasing.

[0022] In order to achieve the above object, a mass damper using a pressure motor according to the invention as set forth in claim 4 comprises a cylinder filled with a working fluid and having a hollow rod fitting portion extending in an axial direction, a piston slidably provided within the cylinder and dividing the interior of the cylinder into a first fluid chamber and a second fluid chamber, a piston rod integral with the piston, extending in the axial direction, and fitting into the rod fitting portion of the cylinder, a communication passage bypassing the piston and communicating with the first and second fluid chambers, and a pressure accumulator chamber provided in the piston rod and communicating with the first and second fluid chambers, and the working fluid in the first and second fluid chambers flows into the pressure accumulator chamber to increase pressure. the pressure motor having a rotor accommodated in the housing and converting the flow of the working fluid caused by the sliding of the piston into rotational motion of the rotor; a flywheel that is rotationally driven by the rotor and exhibits a vibration suppression effect; an accumulator passage that opens at one end to the outer peripheral surface of the rod fitting portion of the cylinder and communicates at the other end with the pressure accumulation chamber of the accumulator; and a drain piping that communicates with the drain passage and is connected to the opening of the accumulator passage in order to discharge the working fluid from the housing.

[0023] The mass damper using the pressure motor of the present invention has the same basic configuration as the mass damper of claim 1, and therefore similarly obtains the vibration suppression effect of the mass damper and the pressure accumulation effect of the first and second fluid chambers by the accumulator. In addition, when the pressure in the housing of the pressure motor rises, the working fluid in the housing is discharged from the drain passage through the drain piping and the accumulator passage to the pressure accumulation chamber of the accumulator, thereby preventing the pressure in the housing from increasing.

[0024] According to the present invention, the accumulator passage opens to the outer peripheral surface of the rod fitting portion of the cylinder into which the piston rod fits and communicates with the accumulator chamber of the accumulator, and the drain pipe communicates with the drain passage and is connected to the opening of the accumulator passage. Since the drain pipe is connected between the housing and the cylinder, which are immovable members, unlike the drain hose of the invention of claim 1, it is not pushed or pulled by the moving piston rod during operation of the mass damper. Therefore, unlike the invention of claim 1, it is possible to avoid problems such as damage caused by bending of the drain pipe and leakage of the working fluid resulting therefrom without using a flexible drain hose.

[0025] Also, as in the case of the drain hose of claim 1, the drain hose can be easily attached by simply connecting the drain piping from the outside to the opening of the accumulator passage formed on the outer surface of the cylinder, improving the ease of assembly. Furthermore, since the drain piping is arranged on the outside of the cylinder and can be visually observed from the outside, it is possible to obtain the advantage that the condition of the drain piping, such as damage thereto or leakage of the working fluid, can be easily grasped.

[0026] The invention according to claim 5 is a mass damper using the pressure motor according to claim 4, characterized in that the accumulator passage has a cylinder through-hole that opens onto an outer peripheral surface of a rod fitting portion of the cylinder and extends inwardly through the rod fitting portion, an annular communicating passage that is defined by sealing a gap between the rod fitting portion and the piston rod at two positions in the axial direction and communicates with the cylinder through-hole, and a rod through-hole that penetrates a peripheral wall of the accumulator chamber of the piston rod and always communicates with the communicating chamber and the accumulator chamber regardless of the position of the piston rod, and a drain pipe is connected to the opening of the cylinder through-hole.

[0027] In this configuration, the accumulator passage is defined by a cylinder through hole that opens onto the outer peripheral surface of the rod fitting portion of the cylinder and extends inward, and by sealing the gap between the rod fitting portion and the piston rod, and has an annular connecting passage that communicates with the cylinder through hole, and a rod through hole that penetrates the peripheral wall of the accumulator chamber of the piston rod and is always connected to the annular connecting passage and the accumulator chamber regardless of the position of the piston rod, and the drain pipe is connected to the opening of the cylinder through hole.

[0028] According to this configuration, when the pressure inside the housing rises, the working fluid inside the housing flows from the drain passage through the drain piping, the cylinder through-hole opening into the rod fitting portion of the cylinder, the annular communication passage between the rod fitting portion and the piston rod, and the rod through-hole penetrating the peripheral wall of the pressure accumulator of the piston rod, and thus the housing is prevented from becoming over-pressurized. Also, the drain piping and the accumulator passage are configured to satisfy the conditions of claim 4, and therefore, the effects of claim 4, such as preventing problems such as damage to the drain piping and the resulting leakage of the working fluid, and improving the ease of assembly of the drain piping, can be similarly obtained.

[0029] The invention according to claim 6 is characterized in that, in the mass damper using the pressure motor according to claim 4 or 5, it further comprises a check valve provided in one of the drain piping and the cylinder through-hole, which allows only the flow of working fluid from the housing side to the accumulator side.

[0030] According to this configuration, when the pressure inside the housing becomes greater than the pressure in the pressure accumulator, the check valve opens, thereby releasing the pressure inside the housing to the pressure accumulator and maintaining the pressure below the pressure accumulator, thereby reliably preventing the pressure inside the housing from increasing. [Brief description of the drawings]

[0031] [Figure 1] 1 is a vertical cross-sectional view showing a part of a mass damper according to a first embodiment of the present invention, with a cutaway view. [Diagram 2]FIG. 4 is a vertical sectional view showing a mass damper according to a modified example of the first embodiment. [Diagram 3] FIG. 6 is a vertical sectional view showing a mass damper according to a second embodiment of the present invention with a piston rod in an initial state (neutral position). [Figure 4] FIG. 11 is a vertical cross-sectional view showing a mass damper according to a second embodiment with a piston rod in a fully extended state. [Diagram 5] FIG. 11 is a vertical sectional view showing a mass damper according to a second embodiment in a state in which a piston rod is fully contracted. [Figure 6] FIG. 11 is a vertical sectional view showing a mass damper according to a modified example of the second embodiment. [Figure 7] FIG. 1 is a vertical cross-sectional view showing a mass damper proposed by the applicant. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. As shown in Fig. 1, a mass damper 1 according to a first embodiment of the present invention includes a 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 arranged in the communication passage 4, a flywheel 9 connected to an output shaft 8 of the gear motor 5, an accumulator 21 provided on a piston rod 10, and the like.

[0033] The cylinder 2 has a cylindrical peripheral wall 2a and first and second end walls 2b, 2c integrally provided at both ends of the peripheral wall 2a, and these three walls 2a-2c define the internal space of the cylinder 2. The central portion in the axial direction of the peripheral wall 2a is a rod fitting portion 2d with a large wall thickness (small inner diameter), and the space between the rod fitting portion 2d and the second end wall 2c is a rod accommodating portion 2e. A second attachment FL2 is provided to the second end wall 2c via a ball joint BJ.

[0034] The piston 3 is provided in the cylinder 2 so as to be slidable in the axial direction, and divides the internal space of the cylinder 2 into a first fluid chamber 2f and a second fluid chamber 2g. The first and second fluid chambers 2f, 2g and the communication passage 4 are filled with hydraulic oil HF. The hydraulic oil HF is an ordinary oil having an appropriate viscosity.

[0035] A piston rod 10 is provided integrally with the piston 3 and concentrically. The piston rod 10 is composed of a first rod portion 10a extending from the piston 3 to one side in the axial direction (the left side in FIG. 1) and a second rod portion 10b extending to the other side (the right side in FIG. 1). The first rod portion 10a is supported by the first end wall 2b in a liquid-tight manner and partially protrudes outside the cylinder 2. A first mounting fixture FL1 is provided at the tip end of the first rod portion 10a via a ball joint BJ. The second rod portion 10b is supported by the rod fitting portion 2d of the cylinder 2 in a liquid-tight manner and is partially accommodated in the rod accommodation portion 2e.

[0036] The accumulator 21 is provided in the second rod portion 10b to store a part of the pressure in the cylinder 2 that increases with the temperature rise of the hydraulic oil HF, etc. Specifically, the accumulator 21 has a hollow casing portion 22 formed in about ⅔ of the range of the tip side of the second rod portion 10b, a piston 24 that is slidably provided in the casing portion 22 and defines a pressure accumulator chamber 23 on the piston 3 side, and a set spring 25 that biases the piston 24 toward the pressure accumulator chamber 23. In addition, a second rod communication hole 10d is formed along the second rod portion 10b. The second rod communication hole 10d communicates with the pressure accumulator chamber 23 at one end and with the piston communication hole 3a of the piston 3 at the other end.

[0037] On the other hand, the piston 3 is provided with first and second communication holes that penetrate in the axial direction and communicate with the first and second fluid chambers 2f, 2g, a third communication hole that extends in the vertical direction to connect the first and second communication holes, and a piston communication hole 3a that extends from the center of the third communication hole to both sides in the axial direction and communicates with the second rod communication hole 10d. The first communication hole is provided with check valves 26, 26 on both sides of the third communication hole. Each check valve 26 is configured to allow only the flow of hydraulic oil HF from the third communication hole side to the first or second fluid chamber 2f, 2g side. In addition, the second communication hole is provided with orifices 27, 27 on both sides of the third communication hole.

[0038] In the above configuration, when the pressure in the cylinder 2 increases due to a rise in temperature of the hydraulic oil HF, the hydraulic oil HF slowly flows from the first and second fluid chambers 2f, 2g through the second communication hole of the piston 3, the orifices 27, 27, the third communication hole, the piston communication hole 3a, and the second rod communication hole 10d into the pressure accumulation chamber 23 of the accumulator 21. As a result, the set spring 25 is compressed via the piston 24, and part of the pressure in the first and second fluid chambers 2f, 2g is accumulated in the accumulator 21, thereby avoiding problems caused by a pressure rise due to a temperature rise of the hydraulic oil HF.

[0039] When the temperature of the hydraulic oil HF drops from this state, the hydraulic oil HF in the accumulator chamber 23 is returned to the first and second fluid chambers 2f, 2g via the second rod communication hole 10d, the piston communication hole 3a, the third communication hole, the open check valves 26, 26, and the first communication hole, thereby releasing the pressure accumulated in the accumulator 21 and restoring the original state.

[0040] Further, a first communication passage 3b and a second communication passage 3c for relief purposes are formed in the piston 3, penetrating in the axial direction. A first relief valve 11 and a second relief valve 12 are provided in the first and second communication passages 3b, 3c, respectively. The first and second relief valves 11, 12 have the same configuration, are configured as normally closed valves, and include a valve body and a spring that biases the valve body in a valve closing direction.

[0041] The first relief valve 11 closes the first communication passage 3b until the pressure of the hydraulic oil HF in the first fluid chamber 2f reaches a predetermined pressure, and opens the first communication passage 3b when the pressure reaches the predetermined pressure. This allows the pressure in the first fluid chamber 2f to escape to the second fluid chamber 2g side via the first communication passage 3b, and is limited to a predetermined pressure or lower. Similarly, the second relief valve 12 closes the second communication passage 3c until the pressure in the second fluid chamber 2g reaches a predetermined pressure, and opens the second communication passage 3c when the pressure reaches the predetermined pressure. This allows the pressure in the second fluid chamber 2g to escape to the first fluid chamber 2f side via the second communication passage 3c, and is limited to a predetermined pressure or lower.

[0042] The gear motor 5 is, for example, an internal type, and is disposed in the center of the communication passage 4. The gear motor 5 has a housing 6 communicating with the communication passage 4 via two inlets 6a, 6a, a rotatable input gear and an output gear (neither shown) housed in the housing 6 and meshing with each other, and an output shaft 8 integrally provided with the output gear. The housing 6 is supported by the peripheral wall 2a of the cylinder 2. A drain passage (not shown) for discharging the hydraulic oil HF is provided within the housing 6. The output shaft 8 is liquid-tightly supported by the housing 6 via a seal (not shown). Note that the gear motor 5 may be an external type instead of an internal type.

[0043] The flywheel 9 is made of a material having a relatively large specific gravity, such as steel, and is formed, for example, in a disk shape. The flywheel 9 is integrally provided coaxially with the output shaft 8.

[0044] A drain hose 31 is connected between the housing 6 and the first rod portion 10a of the piston rod 10. The drain hose 31 is for discharging the hydraulic oil HF from the housing 6 to prevent the pressure inside the housing 6 from increasing, and is flexible and attached between the housing 6 and the first rod portion 10a in a moderately loosened state. Specifically, one end of the drain hose 31 communicates with the drain passage of the housing 6, and the other end is connected to the opening 29c of the first rod communication hole 10c formed in the first rod portion 10a.

[0045] The first rod communicating hole 10c opens on the surface of the first rod portion 10a, extends radially inward, and also extends concentrically in the axial direction from its inner end to communicate with the piston communicating hole 3a of the piston 3. As will be understood from the above, the radially extending portion of the first rod communicating hole 10c constitutes a first passage portion 29a of the accumulator passage 29, and the axially extending portion of the first rod communicating hole 10c, the piston communicating hole 3a, and the second rod communicating hole 10d constitute a second passage portion 29b of the accumulator passage 29 that communicates with the pressure accumulation chamber 23 of the accumulator 21.

[0046] In addition, the drain hose 31 is provided with a check valve 32 for drainage at a position close to the housing 6. The check valve 32 is configured to allow only the flow of the hydraulic oil HF from the housing 6 side to the pressure accumulation chamber 23 side of the accumulator 21.

[0047] Furthermore, a joint tee 33 is provided in the drain hose 31 between the housing 6 and the check valve 32, and a tapered plug 34 for bleeding air is attached to the joint tee 33. Reference numerals 35, 35 in Fig. 1 denote pedestals provided in the cylinder 2 to prevent the mass damper 1 from rotating or tipping over. Reference numeral 37 denotes a hydraulic oil injection hole formed in the rod fitting portion 2d of the cylinder 2 for injecting hydraulic oil HF into the second fluid chamber 2g, and reference numeral 38 denotes a check valve provided in the hydraulic oil injection hole 37 to prevent backflow.

[0048] The mass damper 1 having the above configuration is attached, for example, between two parts of a structure that are subject to relative displacement (for example, an upper beam and a lower beam) via first and second mounting fixtures FL1 and FL2, and used as a vibration control device. The operation of the mass damper 1 will be described below.

[0049] 1 shows the initial state of the mass damper 1, and when a structure vibrates during an earthquake or the like, the piston 3 reciprocates in the cylinder 2 in response to the relative displacement between the two parts to which the mass damper 1 is attached. As a result, the hydraulic oil HF in the first or second fluid chamber 2f, 2g is pushed out by the piston 3 and 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 2g, 2f.

[0050] The pressure caused by the flow of this hydraulic oil HF is converted into 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 rotated, thereby exerting a rotational inertia mass effect (inertia force). In addition, a viscous damping effect (viscous force) is exerted due to the viscous resistance when the hydraulic oil HF flows through the communication passage 4, the inside of the gear motor 5, etc., and thus, in addition to the rotational inertia mass effect, a vibration suppression effect for the structure is exerted.

[0051] Furthermore, for example, when the pressure inside the housing 6 rises due to the mass damper 1 and the gear motor 5 operating for a long period of time in response to the response of the structure to a long-period earthquake motion input, and becomes higher than the pressure in the accumulator chamber 23 of the accumulator 21, the check valve 32 opens. This causes a part of the hydraulic oil HF inside the housing 6 to flow into the accumulator chamber 23 through the drain passage, the drain hose 31, the first rod communicating hole 10c, the piston communicating hole 3a, and the second rod communicating hole 10d, and is then discharged. As a result, the pressure inside the housing 6 is released to the accumulator chamber 23 and is maintained at or below the pressure in the accumulator chamber 23, thereby reliably preventing the pressure inside the housing 6 from increasing.

[0052] In addition, due to the function of the accumulator 21 described above, the pressure in the accumulator chamber 23 is maintained at a low pressure, which is considerably smaller than the pressure in the first and second fluid chambers 2f, 2g on the high pressure side, which increases with the movement of the piston 3. Therefore, the pressure acting on the drain hose 31 and the check valve 32 becomes very small, for example, compared to a case where a drain hose is connected to the first or second fluid chamber 2f, 2g and a check valve is provided in the drain hose. As a result, there is an advantage that the risk of leakage of the hydraulic oil HF from the connection portion of the drain hose 31 is reduced, and an inexpensive check valve with low pressure resistance can be used.

[0053] Furthermore, the drain hose 31 is flexible, is disposed outside the piston rod 10, and is attached in a loose state between the housing 6 and the first rod portion 10a. With this configuration, the drain hose 31 smoothly follows the piston rod 10 that moves relative to the housing 6 during operation of the mass damper 1, so that even if the drain hose 31 is repeatedly pushed and pulled, it is possible to reliably prevent problems such as damage due to bending and leakage of the working fluid.

[0054] In addition, since the drain hose 31 can be visually inspected from the outside, if any malfunction such as damage or leakage of the hydraulic oil HF occurs, the situation can be easily grasped. Furthermore, unlike the mass damper 101 in Fig. 7, the drain hose 31 can be easily attached by simply connecting it to the opening 29c of the first rod portion 10a from the outside, which greatly improves the ease of assembly.

[0055] 2 shows a mass damper 1A according to a modification of the first embodiment described above. This mass damper 1A is different from the mass damper 1 in FIG. 1 in that check valves 36, 36 for bleeding air are provided at the apexes of both ends of the communication passage 4. The check valve 36 allows fluid to flow only from the top to the bottom, and is configured to open when the ball is manually pushed from above. With this configuration, after assembling the mass damper 51A, for example, the air that has accumulated below the check valve 36 can be successfully and easily bled by forcibly pushing down the ball.

[0056] Next, a mass damper 51 according to a second embodiment of the present invention will be described with reference to Figs. 3 to 5. In these figures, components that are the same as or equivalent to those of the mass damper 1 of the first embodiment are given the same reference numerals. As is clear from a comparison with Fig. 1, the mass damper 51 differs from the mass damper 1 of the first embodiment in that a drain pipe 52 for discharging the hydraulic oil HF from the housing 6 is connected to the rod fitting portion 2d of the cylinder 2, and in the configuration of an accumulator passage 53 that communicates with the drain pipe 52 and the accumulator chamber 23. The configuration of the mass damper 51 will be described below, focusing on the different parts.

[0057] The drain pipe 52 does not need to be flexible like the drain hose 31 of the first embodiment, and is made of a metal pipe such as a steel pipe having rigidity. One end of the drain pipe 52 communicates with the drain passage of the housing 6, and the other end is connected to an opening 53d of a cylinder through-hole 53a formed in the rod fitting portion 2d of the cylinder 2.

[0058] The accumulator passage 53 is made up of the cylinder through-hole 53a, the annular communicating passage 53b, and the rod through-hole 53c. The cylinder through-hole 53a is disposed at the center in the axial direction of the rod fitting portion 2d of the cylinder 2, opens to the outer circumferential surface thereof, and extends radially through the peripheral wall.

[0059] The annular communication passage 53b is defined in an annular shape by sealing the gap between the rod fitting portion 2d and the second rod portion 10b of the piston rod 10 with two annular seals 54, 54 at both axial ends, and communicates with the cylinder through-hole 53a. The axial length of the annular communication passage 53b (= the distance between the seals 54, 54) is greater than the maximum stroke of the piston 3 and the piston rod 10 in the mass damper 51.

[0060] The rod through hole 53c penetrates the peripheral wall of the pressure accumulator chamber 23 of the piston rod 10, and communicates with the annular communicating passage 53b and the pressure accumulator chamber 23. As shown in Fig. 3, the rod through hole 53c is disposed so that its axial position coincides with the cylinder through hole 53a when the piston 3 and the piston 10 are in their initial states (neutral positions). Due to the above configuration and dimensional relationships, as shown in Figs. 3 to 5, the rod through hole 53c always communicates with the annular communicating passage 53b when the piston rod 10 is in any position including the fully extended state (Fig. 4) and the fully retracted state (Fig. 5), i.e., regardless of the position of the piston rod 10.

[0061] Further, the cylinder through-hole 53a is provided with a drain check valve 55 at a position close to the opening 53d. The check valve 55 is configured to allow only the flow of the hydraulic oil HF from the housing 6 side to the accumulator chamber 23 side of the accumulator 21.

[0062] The basic operation of the mass damper 51 configured as above is the same as that of the mass damper 1 of the first embodiment described above. That is, when a structure vibrates, the piston 3 reciprocates in the cylinder 2 from the initial state (neutral position) in Fig. 3 in response to the relative displacement between two parts of the structure to which the mass damper 51 is attached, causing the hydraulic oil HF to flow through the communication passage 4, the pressure of which is converted into rotation of the gear motor 5, and the flywheel 9 is rotationally driven, thereby exerting a rotational inertia mass effect. This rotational inertia mass effect, combined with a viscous damping effect due to the viscous resistance when the hydraulic oil HF flows through the communication passage 4, inside the gear motor 5, etc., exerts an effect of suppressing vibration of the structure. In addition, when the pressure inside the cylinder 2 increases due to an increase in the temperature of the hydraulic oil HF, etc., the hydraulic oil HF flows from the first and second fluid chambers 2f, 2g through the piston communication hole 3a and the second rod communication hole 10d into the pressure accumulation chamber 23 of the accumulator 21, and a portion of the pressure inside the first and second fluid chambers 2f, 2g is stored in the accumulator 21.

[0063] Furthermore, according to the mass damper 51 of this embodiment, when the pressure inside the housing 6 increases due to a long period of operation of the gear motor 5, etc., and becomes higher than the pressure in the accumulator chamber 23 of the accumulator 21, the check valve 55 opens. As a result, a part of the hydraulic oil HF inside the housing 6 flows into the accumulator chamber 23 through the accumulator passage 53 (the cylinder through-hole 53a, the annular communicating passage 53b, and the rod through-hole 53c) which is always in communication with the drain passage and the drain pipe 52, and is then discharged.

[0064] For example, as shown in FIG. 3, when the piston rod 10 of the mass damper 51 is in the initial state (neutral position), the axial positions of the cylinder through-hole 53a and the rod through-hole 53c of the accumulator passage 53 are aligned with each other, so that the hydraulic oil HF flows from the cylinder through-hole 53a, across the annular communicating passage 53b, to the rod through-hole 53c directly below, as indicated by the arrows in the figure, and then flows into the accumulator chamber 23.

[0065] 4, when the piston rod 10 is in the most extended state (the state where it has moved most to the left in the figure), the rod through-hole 53c is shifted most to the left with respect to the cylinder through-hole 53a, but is located near the left end of the annular communicating passage 53b and communicates with it. Therefore, as shown by the arrow in the figure, the hydraulic oil HF flows from the cylinder through-hole 53a into the annular communicating passage 53b, moves leftward, and then flows into the rod through-hole 53c and into the pressure accumulator chamber 23.

[0066] 5, when the piston rod 10 is in a most contracted state (a state in which the piston rod 10 has moved most to the right in the figure), the rod through-hole 53c is located near the right end of the annular communicating passage 53b and communicates with it, although it is shifted most to the right with respect to the cylinder through-hole 53a. Therefore, the hydraulic oil HF flows from the cylinder through-hole 53a into the annular communicating passage 53b, moves to the right, and then flows into the rod through-hole 53c and into the pressure accumulator chamber 23, as shown by the arrow in the figure.

[0067] As described above, the communication state of the accumulator passage 53 is always ensured regardless of the position of the piston rod 10. Therefore, when the pressure in the housing 6 rises and the check valve 55 opens, the hydraulic oil HF can be continuously and smoothly discharged into the accumulator chamber 23 via the accumulator passage 53, thereby preventing the pressure in the housing 6 from becoming high.

[0068] Furthermore, because the drain pipe 52 is connected between the housing 6, which is an immovable member, and the cylinder 2, it is not pushed or pulled by the moving piston rod 10 during operation of the mass damper 51, unlike the drain hose 31 of the first embodiment. Therefore, unlike the first embodiment, it is possible to avoid problems such as damage due to bending of the drain pipe 52 and leakage of the operating HF caused thereby, without using a flexible drain hose 31.

[0069] 7, the drain pipe 52 can be easily attached simply by connecting it from the outside to the opening 53d of the accumulator passage 53 formed in the outer surface of the cylinder 2, thereby significantly improving the ease of assembly. Furthermore, since the drain pipe 52 is disposed on the outside of the cylinder and can be visually observed from the outside, it is possible to obtain an advantage that the conditions of the drain pipe 52, such as damage thereto and leakage of the hydraulic oil HF, can be easily grasped.

[0070] 6 shows a mass damper 51A according to a modification of the second embodiment described above. This mass damper 51A differs from the mass damper 51 in FIG. 3 in that check valves 36 for bleeding air are provided at the tops of both ends of the communication passage 4 and at the top of the pipe 6b communicating with the housing 6. The check valve 36 allows fluid to flow only from the top to the bottom, and is configured to open when the ball is manually pushed from above. With this configuration, after assembling the mass damper 51A, for example, the air that has accumulated below the check valve 36 can be successfully and easily bled by forcibly pushing down the ball.

[0071] In addition, reference numeral 56 in FIG. 6 denotes a hydraulic oil injection hole formed in the rod fitting portion 2d of the cylinder 2 so as to communicate with the annular communication passage 53b in order to inject hydraulic oil HF into the pressure accumulation chamber 23 of the accumulator 21, and reference numeral 57 denotes a check valve provided in the hydraulic oil injection hole 56 to prevent backflow.

[0072] The present invention is not limited to the embodiments and modifications described above, and can be embodied in various forms. For example, in the first embodiment, the accumulator 21 is disposed in the second rod portion 10b of the piston rod 10 housed in the cylinder 2, and an opening 29c of the accumulator passage 29 to which the drain hose 31 is connected is disposed in the first rod portion 10a protruding to the outside of the cylinder 2, and the accumulator passage 29 is formed so as to penetrate the first rod portion 10a, the piston 3, and the second rod portion 10b and communicate with the accumulator chamber 23. This configuration is not essential, and for example, the accumulator may be housed in the first rod portion 10a, and an accumulator passage may be provided so as to penetrate the peripheral wall of the accumulator chamber, and the drain hose 31 may be connected to the opening of the accumulator passage.

[0073] In the second embodiment, the drain pipe 52 has been described as being rigid. However, as in the first embodiment, a flexible drain hose may of course be used as the drain pipe 52.

[0074] Furthermore, the check valves 32, 55 that allow only the flow of hydraulic oil HF from the housing 6 side to the accumulator chamber 23 side of the accumulator 21 are provided in the drain hose 31 in the first embodiment and in the cylinder through-hole 53a in the second embodiment, but the check valve 55 in the second embodiment may be disposed in the drain pipe 52. Moreover, since the pressure in the housing 6 often becomes higher than the pressure in the accumulator chamber 23 during operation of the mass damper, it is possible to omit these check valves 32, 55.

[0075] Furthermore, in the embodiment, a gear motor is used as the pressure motor, but other types of pressure motors, such as a piston motor, a vane motor, or a screw motor, may be used. Also, in the embodiment, it has been described that normal hydraulic oil HF is used as the working fluid of the damper, but it goes without saying that other appropriate working fluids may be used. In addition, the detailed configuration may be appropriately changed within the scope of the spirit of the present invention. [Explanation of symbols]

[0076] 1 Mass damper according to the first embodiment 1A Mass damper according to a modification of the first embodiment 2 Cylinder 2d Rod fitting 2f 1st fluid chamber 2g 2nd fluid chamber 3 Piston 4 passages 5 Gear motor (pressure motor) 6. Housing 8 Output shaft (rotating body) 9 Flywheel 10 Piston rod 10a First rod part 10b Second rod part 21 Accumulator 23 Pressure accumulator 29 Accumulator passage 29a 1st passage section 29b 2nd passage section 29c aperture 31 Drain hose 32 Check valve 51 Mass damper according to the second embodiment Mass damper according to a modified example of the second embodiment 52 Drain piping 53 Accumulator passage 53a Cylinder through hole 53b Circular passage 53c Rod through hole 53d aperture 54 Seal 55 Check valve HF Actuating Oil (Actuating Fluid)

Claims

1. A cylinder filled with a working fluid; a piston slidably disposed within the cylinder and dividing the interior of the cylinder into a first fluid chamber and a second fluid chamber; a piston rod that is integral with the piston, extends in an axial direction, and partially protrudes outside the cylinder; a communication passage that bypasses the piston and communicates with the first and second fluid chambers; an accumulator provided in the piston rod, the accumulator having a pressure accumulator chamber communicating with the first and second fluid chambers, the accumulator accumulating pressure by the working fluid in the first and second fluid chambers flowing into the pressure accumulator chamber; a pressure motor including a housing having a drain passage communicating with the communication passage and for discharging the working fluid, and a rotor housed in the housing, the pressure motor converting the flow of the working fluid caused by the sliding of the piston into a rotational motion of the rotor; A flywheel that is rotationally driven by the rotor and exhibits a vibration suppression effect; an accumulator passage having one end portion that opens onto a surface of a portion of the piston rod that protrudes from the cylinder and having another end portion that communicates with the pressure accumulator of the accumulator; a flexible drain hose in communication with the drain passage and loosely connected to an opening of the accumulator passage for draining hydraulic fluid from the housing; A mass damper using a pressure motor, comprising:

2. the piston rod has a first rod portion extending from the piston to one side in the axial direction and partially protruding outside the cylinder, and a second rod portion extending from the piston to the other side in the axial direction, accommodated in the cylinder, and provided with the accumulator; the accumulator passage includes a first passage portion that opens on a surface of the first rod portion and extends inward, and a second passage portion that is connected to an inner end of the first passage portion, extends in the axial direction through the first rod portion, the piston, and the second rod portion, and communicates with the pressure accumulator chamber, 2. The mass damper using a pressure motor according to claim 1, wherein the drain hose is connected to an opening of the first passage portion.

3. 3. The mass damper using a pressure motor according to claim 1, further comprising a check valve provided in the drain hose for allowing only a flow of the working fluid from the housing side to the accumulator side.

4. a cylinder filled with a working fluid and having a hollow rod fitting portion extending in an axial direction; a piston slidably disposed within the cylinder and dividing the interior of the cylinder into a first fluid chamber and a second fluid chamber; a piston rod that is integral with the piston, extends in an axial direction, and fits into the rod fitting portion of the cylinder; a communication passage that bypasses the piston and communicates with the first and second fluid chambers; an accumulator provided in the piston rod, the accumulator having a pressure accumulator chamber communicating with the first and second fluid chambers, the accumulator accumulating pressure by the working fluid in the first and second fluid chambers flowing into the pressure accumulator chamber; a pressure motor including a housing having a drain passage communicating with the communication passage and for discharging the working fluid, and a rotor housed in the housing, the pressure motor converting the flow of the working fluid caused by the sliding of the piston into a rotational motion of the rotor; A flywheel that is rotationally driven by the rotor and exhibits a vibration suppression effect; an accumulator passage having one end portion that opens to an outer circumferential surface of the rod fitting portion of the cylinder and having another end portion that communicates with the pressure accumulator chamber of the accumulator; a drain pipe communicating with the drain passage and connected to an opening of the accumulator passage for discharging working fluid from the housing; A mass damper using a pressure motor, comprising:

5. the accumulator passage includes a cylinder through-hole that opens into an outer peripheral surface of the rod fitting portion of the cylinder and extends inwardly through the rod fitting portion; an annular communication passage that is defined by sealing a gap between the rod fitting portion and the piston rod at two positions in the axial direction and communicates with the cylinder through-hole; and a rod through-hole that penetrates a peripheral wall of the pressure accumulator chamber of the piston rod and always communicates with the annular communication passage and the pressure accumulator chamber regardless of the position of the piston rod, 5. The mass damper using a pressure motor according to claim 4, wherein the drain pipe is connected to an opening of the cylinder through hole.

6. 6. The mass damper using a pressure motor according to claim 4 or 5, further comprising a check valve provided in one of the drain pipe and the cylinder through hole, the check valve allowing only a flow of working fluid from the housing side to the accumulator chamber side.

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