Pressure motor type mass damper

Abstract

To provide a pressure motor type mass damper which can reliably prevent the pressure in a housing of a pressure motor from becoming excessively high even when the mass damper is operated for a long time.SOLUTION: A pressure motor type mass damper 1 of the present invention comprises: a piston 3 which slides in a cylinder 2 filled with a working fluid HF and partitions the cylinder into first and second fluid chambers 2e, 2f; a communication path 4 bypassing the piston 3 and communicating with the first and second fluid chambers 2e, 2f; a gear motor 5 having a housing 6 communicating with the communication path 4 and converting flow of the working fluid HF into a rotation motion; and a flywheel 9 driven for rotation by the gear motor 5 and exerting a vibration suppression effect. The mass damper also comprises a pair of accumulators 15, 15 arranged in the communication path 4, a check valve 23 that allows only a flow of the working fluid HF from an oil chamber 17 of each accumulator 15 to the communication path 4 side, and a drain pipe 21 connected to a drain passage of the housing 6 and the oil chambers 17, 17.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 suppress vibration of a structure by converting the pressure of a working fluid generated in association with vibration of the structure into rotational motion of a rotating mass. [Background technology]

[0002] A known example of a conventional pressure motor-type mass damper is a hydraulic motor-type mass damper, as disclosed in Patent Document 1. In the mass damper shown in FIG. 6, the hydraulic motor has a drain passage for discharging hydraulic oil, and an accumulator is connected to the drain passage. The accumulator is, for example, a spring-type accumulator having a casing, a piston, and a set spring, and the oil chamber of the casing is connected to the drain passage. In this configuration, when the pressure inside the housing of the hydraulic motor increases during operation of the mass damper, the hydraulic oil inside the housing flows into the oil chamber of the accumulator through the drain passage and compresses the set spring, thereby storing a portion of the pressure in the accumulator. This prevents the pressure inside the housing from increasing, thereby maintaining the sealing function of the output shaft of the hydraulic motor and extending the life of the hydraulic motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-94680 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a conventional mass damper with the above-described configuration, when the mass damper operates for a long period of time, for example, in response to a structural response due to a long-period earthquake motion input, the amount of hydraulic oil flowing into the accumulator's oil chamber increases, and the set spring may reach its critical compression state (fully compressed state). In this case, the accumulator's pressure storage capacity reaches its limit, and it is no longer possible to prevent the pressure inside the housing from increasing, resulting in problems such as hydraulic oil leaking from the seal of the output shaft.

[0005] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a pressure motor type mass damper that can reliably prevent excessive pressure buildup inside the housing of the pressure motor even when the mass damper is in operation for a long period of time. [Means for solving the problem]

[0006] To achieve this object, a pressure motor type mass damper 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 housing having a communication passage that bypasses the piston and communicates with the first and second fluid chambers, a drain passage that communicates with the communication passage and is for discharging the working fluid, a rotor housed in the housing, a pressure motor that converts the flow of the working fluid resulting from the sliding of the piston into rotational motion of the rotor, and a flywheel that is rotationally driven by the rotor and exerts a vibration suppression effect. The hydraulic pump comprises a wheel and a pair of accumulators provided in a communication passage on both sides of the pressure motor, each of the pair of accumulators being configured to store pressure by the working fluid flowing into its fluid chamber, the fluid chamber being in communication with the communication passage via a communication pipe, and further comprising a check valve provided in the communication pipe and allowing only the flow of working fluid from the fluid chamber of the accumulator to the communication passage side, and a drain pipe connected at its center to a drain passage of the housing and connected at both ends to the fluid chambers of the pair of accumulators in order to discharge the working fluid from the housing.

[0007] The mass damper of the present invention is a pressure motor type, and as the piston slides in the cylinder, the working fluid flows through the communication passage and into the housing of the pressure motor. The pressure of the working fluid caused by this flow is converted into rotational motion of the rotor of the pressure motor, which rotates and drives the flywheel, thereby achieving a vibration suppression effect.

[0008] The mass damper of the present invention also includes a pair of accumulators, a check valve, and a drain pipe configured and connected as described above. With this configuration, if the pressure inside the housing of the pressure motor increases, for example, due to the mass damper operating for a long period of time, the working fluid inside the housing flows from the drain passage through the drain pipe into the fluid chamber of the low-pressure accumulator, which is the source of piston movement. This activates the accumulator, and the pressure of the working fluid is stored in the accumulator.

[0009] Furthermore, when a check valve provided in a communicating pipe communicating with the fluid chamber of the accumulator opens, the working fluid in the fluid chamber is discharged through the communicating pipe, the check valve, and the communicating passage to the first or second fluid chamber on the low-pressure side of the cylinder, thereby relieving the pressure. As described above, even if the pressure inside the housing of the pressure motor increases due to the operation of the mass damper for a long period of time, the pressure accumulation function of the accumulator and the pressure relief action of the check valve to the first or second fluid chamber on the low-pressure side can reliably prevent excessive pressure inside the housing. As a result, the sealing function of, for example, the output shaft of the pressure motor can be maintained and its lifespan can be extended.

[0010] The invention according to claim 2 is characterized in that, in the pressure motor-type mass damper according to claim 1, a second communication pipe that connects the fluid chamber of the accumulator with the communication passage is provided in parallel with the communication pipe, and an orifice is provided in the second communication pipe.

[0011] With this configuration, on the high-pressure side where the piston moves, when the working fluid flows from the first or second fluid chamber to the fluid chamber of the accumulator via the second communicating pipe, the pressure loss due to the orifice smoothly makes the pressure in the fluid chamber lower than the pressure on the communicating passage side, thereby reliably maintaining the check valve in a closed state. Also, on the low-pressure side where the piston moves from, when the working fluid flows from the fluid chamber of the accumulator via the second communicating pipe, the pressure loss due to the orifice smoothly makes the pressure on the communicating passage side lower than the pressure on the fluid chamber, thereby reliably maintaining the check valve in an open state. As described above, by providing an orifice, the check valve can be opened and closed more smoothly. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a longitudinal cross-sectional view, partly cut away, of a mass damper according to an embodiment of the present invention; [Figure 2] 2 is a vertical cross-sectional view showing the operation of the mass damper of FIG. 1. [Figure 3] 3 is a vertical cross-sectional view showing the operation of the mass damper of FIG. 1, which is reversed from the left to right in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0013] 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 this embodiment includes a cylinder 2, a piston 3 slidably provided within 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 serving as a pressure motor arranged in the communication passage 4, a flywheel 9 connected to an output shaft 8 of the gear motor 5, a pair of accumulators 15, 15 provided at both ends of the communication passage 4, and a drain pipe 21 connected to the accumulators 15, 15.

[0014] 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 to 2c define the internal space of the cylinder 2. A protrusion 2d having a rod accommodating chamber 2g is integrally and concentrically provided on the first end wall 2b, and a first mounting fixture FL1 is attached to its end via a universal joint.

[0015] The piston 3 is axially slidably disposed within the cylinder 2, dividing 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, 2f and the communication passage 4 are filled with hydraulic oil HF. The hydraulic oil HF is a normal hydraulic oil with an appropriate viscosity.

[0016] A piston rod 10 is provided concentrically and integrally with the piston 3. The piston rod 10 extends on both sides of the piston 3 in the axial direction, and on the second end wall 2c side, it passes through the rod guide hole in a liquid-tight manner and extends outward. A second mounting fixture FL2 is provided at the outer end of the piston rod 10 via a universal joint. On the first end wall 2b side, the piston rod 10 passes through the rod guide hole in a liquid-tight manner and extends into the rod accommodating chamber 2g of the protrusion 2d, and a second accumulator 31 is provided at its end.

[0017] The second accumulator 31 stores pressure caused by the temperature expansion of the hydraulic oil HF, and includes a hollow casing 32 formed at the end of the piston rod 10, a piston 34 slidably provided within the casing 32 and defining an oil chamber 33 on the piston 3 side, and a set spring 35 that biases the piston 34 toward the oil chamber 33. A rod communicating hole 10a is formed along the piston rod 10. One end of the rod communicating hole 10a communicates with the oil chamber 33, and the other end extends to the center of the piston 3.

[0018] Meanwhile, the piston 3 is formed with first and second communication holes that penetrate the piston 3 in the axial direction and communicate with the first and second fluid chambers 2e, 2f, and a third communication hole that extends vertically to connect the first and second communication holes and communicates with the rod communication hole 10a. The first communication hole is provided with check valves 36, 36 on both sides of the third communication hole. Each check valve 36 is configured to allow the flow of hydraulic oil HF only from the third communication hole side to the first or second fluid chamber 2e, 2f side. Furthermore, the second communication hole is provided with orifices 37, 37 on both sides of the third communication hole.

[0019] In the above configuration, when the pressure of the hydraulic oil HF in the cylinder 2 increases due to a rise in the temperature of the hydraulic oil HF or the like, the hydraulic oil HF slowly flows from the first and second fluid chambers 2e, 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. As a result, the set spring 35 is compressed via the piston 34, and the pressure of the hydraulic oil HF is stored in the second accumulator 31, thereby avoiding problems caused by a rise in the pressure of the hydraulic oil HF due to a rise in temperature or the like.

[0020] When the temperature of the hydraulic oil HF drops from this state, the hydraulic oil HF in the oil chamber 33 is returned to the first and second fluid chambers 2e, 2f via the rod communication hole 10a, the third communication hole, the open check valves 36, 36, and the first communication hole, thereby releasing the pressure accumulated in the second accumulator 31 and restoring the original state.

[0021] Furthermore, a first communication passage 3d and a second communication passage 3e 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 3d, 3e, 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 the valve closing direction.

[0022] The first relief valve 11 closes the first communication passage 3d until the pressure of the hydraulic oil HF in the first fluid chamber 2e reaches a predetermined pressure, and then opens the first communication passage 3d when the predetermined pressure is reached. This allows the pressure in the first fluid chamber 2e to escape to the second fluid chamber 2f via the first communication passage 3d, and is limited to a pressure equal to or lower than the predetermined pressure. Similarly, the second relief valve 12 closes the second communication passage 3e until the pressure in the second fluid chamber 2f reaches a predetermined pressure, and then opens the second communication passage 3e when the predetermined pressure is reached. This allows the pressure in the second fluid chamber 2f to escape to the first fluid chamber 2e via the second communication passage 3e, and is limited to a pressure equal to or lower than the predetermined pressure.

[0023] The gear motor 5 is, for example, an internal gear type and is arranged in the center of the communication passage 4. The gear motor 5 has a housing 6 which communicates with the communication passage 4 via two inlets and outlets 6a, 6a, a rotatable input gear and an output gear (neither shown) which are housed in the housing 6 and mesh with each other, and an output shaft 8 which is integral 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 also provided within the housing 6. The output shaft 8 is supported liquid-tightly by the housing 6 via a seal (not shown). Note that the gear motor 5 may be an external gear type instead of an internal gear type.

[0024] The flywheel 9 is made of a material with 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.

[0025] The pair of accumulators 15, 15 store the pressure of the hydraulic oil HF inside the housing 6 of the gear motor 5, thereby preventing the pressure inside the housing 6 from becoming too high. Each accumulator 15 is spring-type and is attached to the end of the communicating passage 4. It has a casing 16, a piston 18 that is slidably provided inside the casing 16 and defines an oil chamber 17 on the lower side, and a set spring 19 that biases the piston 18 toward the oil chamber 17.

[0026] The oil chamber 17 is in communication with the communication passage 4 via a first communication pipe 22a, which is provided with a drain check valve 23. The check valve 23 is configured to allow only the flow of hydraulic oil HF from the oil chamber 17 toward the communication passage 4. A second communication pipe 22b branches off from the first communication pipe 22a below the check valve 23 and is connected to the oil chamber 17. An orifice 24 is provided in the second communication pipe 22b.

[0027] The drain pipe 21 is for discharging the hydraulic oil HF from the housing 6 of the gear motor 5 to prevent the pressure inside the housing 6 from increasing. The drain pipe 21 is connected to the drain passage of the housing 6 at the center and to the oil chamber 17 of the accumulator 15 at both ends.

[0028] Although not shown, the mass damper 1 having the above configuration is attached, for example, between two parts of a structure that undergo relative displacement (for example, an upper beam and a lower beam) via first and second mounting fixtures FL1 and FL2, and is used as a vibration control device. The operation of the mass damper 1 will be explained below with reference to Figs. 1 to 3. In Fig. 1, the hydraulic oil HF filled in the cylinder 2 and the communication passage 4 is shown in gray, whereas in Figs. 2 and 3, the gray display is omitted and the arrows indicating the flow of the hydraulic oil HF are shown in white to make them easier to see.

[0029] First, when the structure is not vibrating, the mass damper 1 is in the initial state shown in Figure 1, with the piston 3 located at the axial center of the cylinder 2. When the structure vibrates during an earthquake or other event, the piston 3 reciprocates within the cylinder 2 in response to the relative displacement that occurs between two parts of the structure. Figure 2 shows the operation of the mass damper 1 when the piston 3 moves toward the second fluid chamber 2f (when the piston 3 moves from the first fluid chamber 2e to the second fluid chamber 2f). In this case, the hydraulic oil HF in the second fluid chamber 2f is pushed out by the piston 3, flows into the communicating passage 4, flows through the housing 6 of the gear motor 5, and then returns to the first fluid chamber 2e.

[0030] In this way, the pressure of the hydraulic oil HF when it flows through the communicating passage 4 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 flow resistance when the hydraulic oil HF flows through the communicating passage 4, etc., and this, together with the rotational inertia mass effect, exerts an effect of suppressing vibration of the structure.

[0031] Furthermore, because the check valve 23 on the second fluid chamber 2f side is in a closed state, part of the hydraulic oil HF that has flowed from the second fluid chamber 2f into the communicating passage 4 flows into the oil chamber 17 of the accumulator 15 via the second communicating pipe 22b and the orifice 24. This causes a pressure loss due to the orifice 24, and the pressure in the oil chamber 17 smoothly becomes lower than the pressure on the communicating passage 4 side, thereby reliably maintaining the check valve 23 in a closed state.

[0032] Furthermore, when the pressure inside the housing 6 increases due to the mass damper 1 and gear motor 5 operating for a long period of time, for example, in response to a structural response caused by a long-period earthquake motion input, the hydraulic oil HF inside the housing 6 flows from the drain passage through the drain pipe 21 into the oil chamber 17 of the accumulator 15 on the first fluid chamber 2e side. This activates the accumulator 15, and the pressure of the hydraulic oil HF is stored in the accumulator 15.

[0033] Furthermore, when the check valve 23 near the accumulator 15 opens, the hydraulic oil HF in the oil chamber 17 is discharged to the first fluid chamber 2e via the first communicating pipe 22a, the check valve 23, and the communicating passage 4. In this case, a pressure loss occurs due to the orifice 24 provided in the second communicating pipe 22b, and the pressure on the communicating passage 4 side smoothly becomes lower than the pressure in the oil chamber 17, thereby reliably maintaining the check valve 23 in an open state.

[0034] Figure 3 shows the operation of the mass damper 1 when the piston 3 moves toward the first fluid chamber 2e (when the piston 3 moves from the second fluid chamber 2f to the first fluid chamber 2e), which is the opposite of the case in Figure 2. As is clear from a comparison with Figure 2, the operation in this case is completely reversed from the case in Figure 2, and therefore a description thereof will be omitted.

[0035] Thereafter, as the vibration of the structure ends and the operation of the gear motor 5 ends, the hydraulic oil HF in the oil chamber 17 of the accumulator 15 is slowly returned to the first and second fluid chambers 2e, 2f via the second communicating pipe 22b, the orifice 24 and the communicating passage 4, thereby releasing the pressure stored in the accumulator 15 and restoring it to its original state.

[0036] As described above, according to this embodiment, even if the pressure inside the housing 6 of the gear motor 5 increases due to the operation of the mass damper 1 for a long period of time, the pressure accumulation function of the accumulator 15 and the pressure relief action of the check valve 23 to the first or second fluid chamber 2e, 2f on the low-pressure side can reliably prevent excessive pressure buildup inside the housing 6. As a result, for example, the sealing function of the output shaft 8 of the gear motor 5 can be maintained and the lifespan can be extended.

[0037] Furthermore, the pressure loss caused by the orifice 24 provided in parallel with the check valve 23 allows the check valve 23 to be opened and closed more smoothly.

[0038] The present invention is not limited to the embodiment described above and can be implemented in various forms. For example, in the embodiment, the second communicating pipe 22b and the orifice 24 are provided in parallel with the first communicating pipe 22a and the check valve 23. As described above, the second communicating pipe 22b and the orifice 24 are configured to more smoothly open and close the check valve 23, and therefore can be omitted.

[0039] Furthermore, in the embodiment, a second accumulator 31 for storing pressure due to temperature expansion of the hydraulic oil HF in the cylinder 2 is provided on the piston rod 10, separate from the accumulators 15, 15 for storing the pressure of the hydraulic oil HF in the housing 6. This second accumulator 31 may be eliminated and integrated into the accumulator 15, in which case it is preferable to increase the pressure storage capacity of the accumulator 15. In this configuration, when the pressure in the cylinder 2 increases due to a rise in the temperature of the hydraulic oil HF, the hydraulic oil HF slowly flows from the first and second fluid chambers 2e, 2f through the communicating passage 4, the second communicating pipe 22b, and the orifice 24 into the oil chamber 17 of each accumulator 15, thereby storing pressure in the accumulator 15.

[0040] In addition, in the embodiment, a spring-type accumulator having a piston and a set spring is used as the accumulator, but the type is arbitrary as long as it has the function of storing the pressure of the working fluid. For example, it is possible to use an accumulator of a bladder type or a diaphragm type, or a pressure relief tank type accumulator (using an air spring) in which the piston and set spring, which are components of the accumulator in the embodiment, are removed and an air layer is sealed.

[0041] 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 also be used. Also, in the embodiment, normal hydraulic oil HF is used as the working fluid for the damper, but it goes without saying that other appropriate working fluids may also be used. In addition, the detailed configuration can be changed as appropriate within the scope of the spirit of the present invention. [Explanation of symbols]

[0042] 1 Mass damper 2 cylinders 2e 1st fluid chamber 2f 2nd fluid chamber 3 pistons 4 passages 5 Gear motor (pressure motor) 6. Housing 8 Output shaft (rotating body) 9 Flywheel 15 Accumulator 17 Oil chamber (accumulator fluid chamber) 21 Drain piping 22a 1st communication pipe (communication pipe) 22b 2nd communication pipe 23 Check valve 24 Orifice HF hydraulic oil (working fluid)

Claims

1. a cylinder filled with a working fluid; a piston slidably disposed within the cylinder, the piston dividing the interior of the cylinder into a first fluid chamber and a second fluid chamber; a communication passage that bypasses the piston and communicates with the first and second fluid chambers; a pressure motor having a housing communicating with the communication passage and having a drain passage for discharging the working fluid, and a rotor accommodated in the housing, the pressure motor 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; a pair of accumulators provided in the communication passage on both sides of the pressure motor; Each of the pair of accumulators is configured to accumulate pressure by flowing a working fluid into a fluid chamber, and the fluid chamber is in communication with the communication passage via a communication pipe; a check valve provided in the communication pipe and allowing only the flow of working fluid from the fluid chamber of the accumulator to the communication passage; a drain pipe connected at a central portion to the drain passage of the housing and connected at both ends to the fluid chambers of the pair of accumulators, in order to discharge the working fluid from the housing.

2. 2. The pressure motor-type mass damper according to claim 1, wherein a second communication pipe that communicates the fluid chamber of the accumulator with the communication passage is provided in parallel with the communication pipe, and an orifice is provided in the second communication pipe.

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