Vibration suppression device

Abstract

The present invention provides a vibration suppression device that can effectively suppress the pressure rise of a viscous material even when a viscous material with relatively high viscosity is flowing at high speed, by ensuring that the viscous material passes sufficiently through the flow path of the relief valve. [Solution] In the vibration suppression device of the present invention, the relative displacement between the first and second parts that occurs in conjunction with the vibration of the object to be suppressed is converted into relative rotation between the outer cylinder 3 and the inner cylinder 4 connected to the screw shaft 2a and nut 2b of the ball screw 2, and the vibration suppression effect is exerted by the shear resistance of the viscous material VB filled in the viscous chamber 5 between the two cylinders 3 and 4. The external relief mechanism 6 is connected to the viscous chamber 5 and has first and second communication passages 31 and 32 that extend to the outside of the outer cylinder 5, a relief valve 33 that opens when the pressure in the viscous chamber 5 reaches a predetermined relief pressure Prf and releases the pressure in the viscous chamber 5 from the first communication passage 31 to the second communication passage 32, and a check valve 34 provided in the second communication passage 32.

Description

Technical Field

[0001] The present invention relates to a vibration suppression device that converts linear motion into rotational motion by a ball screw and suppresses vibrations of vibration suppression targets such as structures and vehicles by a viscous damping effect due to the shear resistance of a viscous body.

Background Art

[0002] As a conventional vibration suppression device of this type, for example, the one disclosed in Patent Document 1 is known. This vibration suppression device is a viscous damper using a ball screw, and includes a non-rotatable outer cylinder, a rotatable inner cylinder that defines an annular viscous body chamber between the outer cylinder, a screw shaft, and a ball screw having a nut fixed to the inner cylinder, a viscous body made of silicone oil or the like filled in the viscous body chamber, and a sealing material for sealing the viscous body chamber. A buffer having an air layer is connected to the viscous body chamber. The outer cylinder is connected to a building as a vibration suppression target, and the screw shaft is connected to a foundation that supports the building.

[0003] In this configuration, when the building vibrates during an earthquake, the relative displacement between the building and the foundation is transmitted to the ball screw, and the linear motion of the screw shaft is converted into the rotational motion of the nut, whereby the inner cylinder rotates, and the shear resistance of the viscous body filled in the viscous body chamber between the outer cylinder exhibits the vibration suppression effect of the building. Further, the pressure change due to the expansion and contraction of the viscous body accompanying the temperature change is absorbed by the buffer, and adverse effects such as damage to the sealing material are avoided.

[0004] However, in this conventional viscous damper, when the vibration speed or the cumulative deformation amount due to the repetition of vibrations exceeds the assumption, the temperature and pressure of the viscous body may increase excessively and may not be sufficiently absorbed by the buffer. In that case, as a result of the excessive pressure of the viscous body exceeding the allowable pressure of the sealing material, the sealing material may be damaged and the viscous body may leak out of the viscous body chamber.

[0005] The applicant has already proposed a vibration suppression device to solve these problems (Japanese Patent Application No. 2023-158821). This vibration suppression device, like Patent Document 1, is composed of a ball screw type viscous damper and includes an accumulator located on the outside of the outer cylinder, first and second parallel communication passages communicating with the viscous chamber and the pressure accumulation chamber of the accumulator, a relief valve located in the first communication passage, and a check valve provided in the second communication passage.

[0006] In this configuration, when the viscous material in the viscous chamber undergoes repeated shear deformation in response to prolonged seismic motion, the relief valve remains closed until the pressure of the viscous material reaches the relief pressure of the relief valve. This maintains the pressure state within the viscous chamber, suppressing a decrease in the shear resistance of the viscous material and effectively maintaining the vibration suppression effect. Furthermore, when the pressure of the viscous material in the viscous chamber reaches the relief pressure, the relief valve opens, and the viscous material flows from the viscous chamber into the accumulator's pressure storage chamber via the first connecting passage. As a result, a portion of the pressure within the viscous chamber is stored in the accumulator. This prevents excessive pressure buildup within the viscous chamber and protects the sealing material provided in the viscous chamber from damage. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2012-132479 [Overview of the project] [Problems that the invention aims to solve]

[0008] In the viscous damper developed by the applicant described above, the viscous material is composed of a material with relatively high viscosity, such as silicone oil. On the other hand, since the relief valve is located within the first communication passage, the flow area of ​​the relief valve is limited to less than or equal to the area of ​​the first communication passage. Therefore, especially when the viscous material flows at high speed, the high-viscosity material may not be able to pass sufficiently through the flow path of the relief valve, resulting in insufficient relief function and potentially failing to adequately suppress the pressure rise of the viscous material. Furthermore, the piston position of the accumulator is determined by the balance between the pressure of the viscous material and the spring force of the set spring, and is therefore unstable, making it difficult to obtain stable pressure reduction performance from the accumulator. The viscous damper developed by the applicant has room for improvement in these respects.

[0009] The present invention was made to solve the above-mentioned problems, and aims to provide a vibration suppression device that can effectively suppress the pressure rise of a viscous body by ensuring that the viscous body passes sufficiently through the flow path of the relief valve, even when a viscous body with relatively high viscosity is flowing at high speed, thereby allowing the relief function to be fully exercised. [Means for solving the problem]

[0010] To achieve this objective, the invention according to claim 1 is a vibration suppression device provided between a first part and a second part in a system including a vibration-damping object that undergoes relative displacement during vibration, for the purpose of suppressing vibration of the vibration-damping object, comprising: a ball screw having a screw shaft connected to the first part and a nut screwed onto the screw shaft via a ball, which converts the linear motion of the screw shaft into rotational motion; an outer cylinder connected to the second part; an inner cylinder coaxially arranged inside the outer cylinder, defining a viscous body chamber between itself and the outer cylinder and connected to the nut; a viscous body filled in the viscous body chamber; and a means for sealing the viscous body within the viscous body chamber. The device comprises a sealing material and an external relief mechanism located outside the outer cylinder to release pressure within the viscous body chamber, wherein the external relief mechanism includes a first and second connecting passage, one end of which is connected to different positions within the viscous body chamber and extending outside the outer cylinder; a relief valve, to which the other ends of the first and second connecting passages are connected, which opens when the pressure within the viscous body chamber reaches a predetermined relief pressure, releasing the pressure within the viscous body chamber from the first connecting passage to the second connecting passage; and a check valve provided in the second connecting passage to prevent the flow of viscous material from the viscous body chamber to the relief valve.

[0011] The vibration damping device of the present invention is composed of a viscous damper using a ball screw and is installed between a first part and a second part within a system that includes a vibration-damping target such as a structure or a vehicle. When the vibration-damping target vibrates, the relative displacement between the first and second parts is transmitted between the screw shaft and the outer cylinder of the ball screw and converted into rotational motion by the ball screw, causing the nut of the ball screw and the inner cylinder connected thereto to rotate relative to the outer cylinder. As a result, a vibration damping effect is exerted, which suppresses the vibration of the vibration-damping target by the viscous damping effect due to the shear resistance of the viscous material filled in the viscous chamber between the outer and inner cylinders.

[0012] Furthermore, for example, if the vibration suppression device operates for a long time in response to the damped object's response to long-period ground motion input, repeated shear deformation of the viscous material results in a rise in the temperature of the viscous material, and the pressure inside the viscous material chamber increases due to its thermal expansion. An external relief mechanism for releasing the increased pressure inside the viscous material chamber is located outside the outer cylinder and has a relief valve to which the other ends of the first and second connecting passages, one end of which is connected to different positions in the viscous material chamber, are connected. The relief valve is kept closed until the pressure inside the viscous material chamber reaches the relief pressure of the relief valve, thereby maintaining the high pressure state that has risen up to that point inside the viscous material chamber. This suppresses the unraveling of the entanglement of polymer chains constituting the viscous material during repeated deformation and suppresses the decrease in the shear resistance of the viscous material, thereby maintaining a good vibration suppression effect.

[0013] From this state, when the pressure inside the viscous body chamber rises further and reaches the relief pressure of the relief valve, the relief valve opens. As a result, the viscous body flows out of the viscous body chamber through the first communication passage and the opened relief valve into the second communication passage, thereby releasing the pressure inside the viscous body chamber into the second communication passage. As described above, according to the present invention, the first communication passage through which the viscous body flows, the relief valve, and the second communication passage are all located outside the outer cylinder and connected in series with each other. Therefore, unlike the aforementioned device in which the relief valve is located inside the first communication passage, it is possible to secure a sufficient flow area for the viscous body. As a result, even when a viscous body with relatively high viscosity flows at high speed, the viscous body passes sufficiently through the flow path of the relief valve, allowing the relief function to be fully exercised and the pressure rise of the viscous body to be effectively suppressed. As a result, the pressure inside the viscous body chamber can be kept below the allowable pressure of the sealing material, preventing damage to the sealing material.

[0014] Subsequently, as the vibration of the controlled object ceases, the pressure in the viscous body chamber decreases, and when it falls below the relief pressure, the relief valve closes. Also, when the pressure of the viscous body falls below the pressure in the second communication passage, the check valve in the second communication passage opens. As a result, the viscous body returns from the second communication passage to the viscous body chamber via the check valve, and the pressure in the second communication passage is released into the viscous body chamber, restoring the system to its original state.

[0015] The invention according to claim 2 is a vibration suppression device according to claim 1, characterized in that the second communication passage is composed of a plurality of second communication passages connected in parallel to each other between a plurality of different positions in the viscous chamber and a relief valve, and each of the plurality of second communication passages is provided with a check valve.

[0016] This configuration makes it possible to increase the overall flow area of ​​the second connecting passage. This allows viscous material to flow more smoothly from the relief valve to the second connecting passage, and also enhances the pressure relief effect toward the second connecting passage.

[0017] The invention according to claim 3 is a vibration suppression device according to claim 1 or 2, wherein the relief valve comprises: a casing having a pressure-receiving chamber on one end side through which first and second communication passages communicate; a valve body slidably provided within the casing, which opens the pressure-receiving chamber and connects the first and second communication passages when the pressure in the viscous chamber reaches the relief pressure; a set spring provided within the casing and biasing the valve body toward the pressure-receiving chamber; a spring retainer provided on the other end side of the casing and in contact with the set spring; and a stopper integrally provided with the valve body, which in contact with the set spring and, when the valve body opens, in contact with the spring retainer to limit the maximum deflection of the set spring.

[0018] With this configuration, the initial deflection and initial load (relief pressure) of the set spring can be set by adjusting the spring constant of the set spring that biases the valve body of the relief valve and the position of the stopper. When the pressure in the viscous chamber acting on the pressure-receiving chamber of the casing via the first communication passage reaches the relief pressure, the valve body opens the pressure-receiving chamber, connecting the first and second communication passages, thereby releasing the pressure in the viscous chamber into the second communication passage. Also, when the valve body opens, the stopper contacts the spring retainer, limiting the deflection of the set spring to its maximum deflection, causing the pressure in the viscous chamber to plateau (remain constant). This ensures stable pressure reduction performance of the relief valve.

[0019] The invention according to claim 4 is a vibration suppression device according to claim 3, wherein the set spring has a through hole, the relief valve is integrally provided with the valve body and further has a valve stem that extends through the through hole of the set spring and has male threads formed on its outer circumference, and the stopper has female threads formed on its inner circumference and is screwed onto the valve stem so as to be able to move back and forth.

[0020] With this configuration, the initial deflection and initial load (relief pressure) of the set spring can be finely and easily adjusted by rotating the stopper that contacts the set spring relative to the valve stem and changing the position of the stopper.

[0021] The invention according to claim 5 is characterized in that, in the vibration suppression device described in claim 3, the relief valve further comprises an adjustment member interposed between the casing and the spring retainer for adjusting the maximum deflection of the set spring, which is limited by the stopper.

[0022] With this configuration, the maximum deflection of the set spring, limited by the stopper, and consequently the maximum pressure within the viscous chamber, can be easily adjusted by changing the thickness of the adjustment member interposed between the casing and the spring retainer, thereby adjusting the distance between the stopper and the retaining cover when the vibration suppression device is stopped.

[0023] The invention according to claim 6 is characterized in that, in the vibration suppression device according to claim 3, when the set spring is limited to its maximum deflection, the pressure in the viscous fluid chamber is set to be not higher than the allowable pressure of the sealing material.

[0024] According to this configuration, the maximum pressure in the viscous fluid chamber when the set spring is limited to its maximum deflection can be reliably suppressed to be not higher than the allowable pressure of the sealing material. Thereby, damage to the sealing material can be prevented, and leakage of the viscous fluid from the viscous fluid chamber can be avoided.

[0025] The invention according to claim 7 is characterized in that, in the vibration suppression device according to claim 1, the external relief mechanism is provided separately from the first communication passage and the second communication passage, one end portion thereof is connected to different positions of the viscous fluid chamber, the third communication passage and the fourth communication passage extending to the outside of the outer cylinder, the other end portions of the third communication passage and the fourth communication passage are connected, a second relief valve that opens when the pressure in the viscous fluid chamber reaches a predetermined second relief pressure and releases the pressure in the viscous fluid chamber from the third communication passage to the fourth communication passage side, and a second check valve provided in the fourth communication passage and blocking the flow of the viscous fluid from the viscous fluid chamber to the second relief valve side.

[0026] According to this configuration, the external relief mechanism separately has the third and fourth communication passages, the second relief valve, and the second check valve having the same configuration in addition to the first and second communication passages, the relief valve, and the check valve. In this configuration, when the pressure in the viscous fluid chamber reaches the relief pressure, the relief valve opens, and thereby the pressure in the viscous fluid chamber is released from the first communication passage to the second communication passage side. Also, independently of this operation, when the pressure in the viscous fluid chamber reaches the second relief pressure, the second relief valve opens, and thereby the pressure in the viscous fluid chamber is released from the third communication passage to the fourth communication passage side.

[0027] Therefore, depending on the various elements of the external relief mechanism, particularly the way of setting the relief pressure and the second relief pressure, characteristics such as the timing and amount of pressure release in the viscous fluid chamber, and the damping characteristics of the vibration suppression device based thereon can be set in various ways.

[0028] The invention according to claim 8 is characterized in that, in the vibration suppression device described in claim 7, the second relief pressure of the second relief valve is set to a value greater than the relief pressure of the relief valve.

[0029] In this configuration, when the pressure inside the viscous chamber reaches the relief pressure, the relief valve opens, releasing the pressure inside the viscous chamber. When the pressure inside the viscous chamber rises further and reaches the second relief pressure, the second relief valve opens, releasing the pressure inside the viscous chamber. In this way, by releasing the pressure inside the viscous chamber in stages, the damping characteristics of the vibration suppression device can be set in stages. [Brief explanation of the drawing]

[0030] [Figure 1] This is a front view showing a viscous damper according to the first embodiment of the present invention. [Figure 2] This is a plan cross-sectional view of the viscous damper shown in Figure 1, with the external relief mechanism portion cut out. [Figure 3] This is a longitudinal cross-sectional view showing a portion of the viscous damper in Figure 1, with a section cut out. [Figure 4] Figure 1 shows cross-sectional views of the external relief mechanism of the viscous damper, with (a) the relief valve in the closed state and (b) the relief valve in the fully open state. [Figure 5] This diagram shows two types of installation scenarios for viscous dampers on structures. [Figure 6] This figure shows the damping characteristics of the viscous damper of the first embodiment in response to the opening and closing of the relief valve. [Figure 7] This is a longitudinal cross-sectional view showing a viscous damper according to a modification of the first embodiment, with a portion of it cut away. [Figure 8] This is a plan cross-sectional view showing a portion of the external relief mechanism of the viscous damper according to the second embodiment, with a cutaway. [Figure 9] This is a longitudinal cross-sectional view of the viscous damper shown in Figure 8, with a portion of it cut out. [Figure 10] Figure 9 is a magnified longitudinal cross-sectional view of the external relief mechanism with the two relief valves in the fully open position. [Figure 11] This figure shows the damping characteristics of the viscous damper of the second embodiment in response to the opening and closing of the first relief valve and the second relief valve. [Modes for carrying out the invention]

[0031] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. Figure 1 shows a viscous damper 1A according to a first embodiment of the present invention. The viscous damper 1A constitutes a vibration suppression device that suppresses vibrations of structures such as buildings or vehicles, for example.

[0032] As shown in Figures 1 to 3, the viscous damper 1A comprises a ball screw 2, an outer cylinder 3, an inner cylinder 4, a viscous chamber 5 defined between the outer cylinder 3 and the inner cylinder 4, a viscous body VB filled in the viscous chamber 5, and an external relief mechanism 6.

[0033] The ball screw 2 has a screw shaft 2a and a nut member 2b that rotatably screws onto the screw shaft 2a via a number of balls (not shown). Most of the screw shaft 2a and the nut member 2b are coaxially housed within the outer cylinder 3, with the remaining portion of the screw shaft 2a protruding outside the outer cylinder 3.

[0034] The outer cylinder 3 is made of cylindrical steel. A first support 11a and a second support 11b are provided at one end and the other end of the outer cylinder 3, respectively. The first and second supports 11a and 11b are both perforated short cylinders with different diameters. The first support 11a is fitted inside the outer cylinder 3, and the second support 11b is in contact with the end face of the outer cylinder 3, and they are provided integrally.

[0035] Furthermore, a first cover plate 12a is integrally provided to cover the outer cylinder 3 and the first support 11a, and a second cover plate 12b is integrally provided to cover the second support 11b. The screw shaft 2a of the ball screw 2 extends to the outside through the first cover plate 12a, and a first flange plate 15a is provided at its end via a clevis 14. A second flange plate 15b is also provided on the second cover plate 12b via a clevis 14.

[0036] The inner cylinder 4 is made of cylindrical steel and is positioned inside the outer cylinder 3 and the second support 11b, extending in the axial direction. An annular space with a predetermined gap is defined between the outer cylinder 3 and the inner cylinder 4, and this annular space is the viscous chamber 5. The viscous chamber 5 is filled with a viscous substance VB. The viscous substance VB is made of a substance with relatively high viscosity, such as silicone oil.

[0037] Furthermore, O-ring-shaped sealing materials 21, 21 are provided at both ends of the viscous chamber 5 to seal the viscous body VB inside the viscous chamber 5. The sealing material 21 is made of, for example, a Rotobari seal. While a Rotobari seal has the advantage of being able to suppress leakage of the viscous body while allowing rotation, it has the characteristic of being easily damaged when pressure exceeding the allowable pressure is applied, thereby failing to suppress leakage of the viscous body.

[0038] The inner cylinder 4 is integrally connected to the nut member 2b of the ball screw 2 at one end (the left end in Figure 3). The nut member 2b is supported by the first support 11a, and the inner cylinder 4 is supported by the second support 11b, via a radial bearing 22 and a thrust bearing 23, respectively. With this configuration, the inner cylinder 4 and the nut member 2b are supported by the outer cylinder 3 so as to be rotatable but immovable in the axial direction.

[0039] The external relief mechanism 6 is designed to temporarily release some of the pressure when the pressure of the viscous material VB in the viscous material chamber 5 becomes high, and its main components are located on the upper side of the outer cylinder 3. The external relief mechanism 6 has one first communication passage 31 and a pair of second communication passages 32, 32, a relief valve 33, a check valve 34, and a cover 35 to cover and protect these components.

[0040] As shown in Figures 2 and 3, the first communication passage 31 consists of a communication hole 31a formed in the outer cylinder 3 and a communication pipe 31b connected to the communication hole 31a and extending to the outside. The communication hole 31a penetrates the upper part of the peripheral wall of the outer cylinder 3 vertically at a position approximately 1 / 3 of the total length from one end of the viscous chamber 5 in the axial direction, and communicates with the viscous chamber 5. The communication pipe 31b rises from the communication hole 31a and extends horizontally toward the center of the outer cylinder 3, and is connected to one end of the casing 41 of the relief valve 33, which will be described later.

[0041] Each of the pair of second communication passages 32, 32 consists of a communication hole 32a formed in the outer cylinder 3 and a communication pipe 32b connected to the communication hole 32a and extending to the outside. The communication holes 32a, 32a penetrate vertically through the upper part of the peripheral wall of the outer cylinder 3 at both ends in the axial direction of the viscous chamber 5 (near the sealing material 21) and communicate with the viscous chamber 5. The communication pipes 32b, 32b rise from each communication hole 32a and further extend horizontally in an L-shape toward the center of the outer cylinder 3, and are connected to both sides of the casing 41 of the relief valve 33.

[0042] The check valve 34 is provided in the communication hole 32a of each second communication passage 32. The check valve 34 is configured to block the flow of viscous body VB from the viscous body chamber 5 to the relief valve 33, in other words, to allow only the flow of viscous body VB from the relief valve 33 to the viscous body chamber 5.

[0043] As shown in Figure 4, the relief valve 33 is positioned horizontally and comprises a cylindrical casing 41 to which the first and second communication passages 31 and 32 are connected, a valve body 42 slidably mounted inside the casing 41, a set spring 43 that biases the valve body 42 toward the closed side (towards the first communication passage 31), and a spring retainer 44 for holding down the set spring 43 from the opposite side of the valve body 42.

[0044] The internal space of the casing 41 consists of a small-diameter pressure-receiving chamber 45a at one end and a large-diameter housing chamber 45b connected to the pressure-receiving chamber 45a, which houses the valve body 42 and the set spring 43. A first communication passage 31 (communication pipe 31b) is connected to the pressure-receiving chamber 45a, and two second communication passages 32, 32 (communication pipes 32b) are connected to two radially opposing positions at the boundary between the pressure-receiving chamber 45a and the housing chamber 45b.

[0045] A stepped valve seat 46 is formed at the aforementioned boundary of the casing 41. Meanwhile, the valve body 42 is slidably mounted in the housing chamber 45b of the casing 41 via a sealing material 47 (e.g., an O-ring), and is configured to seat liquid-tightly on the valve seat 46 via a sealing material 48 (e.g., an O-ring) when the valve is closed. A valve stem 49 is integrally mounted on the valve body 42. The valve stem 49 extends axially through the housing chamber 45b of the casing 41, is movably passed through the hole 44a of the spring retainer 44, and protrudes to the outside. Furthermore, a thread is formed on the outer circumferential surface of the valve stem 49, and a nut-shaped spring retainer piece / stopper (hereinafter simply referred to as "stopper") 50 is screwed in so as to be able to move back and forth.

[0046] The set spring 43 is, for example, made up of a number of disc springs with a hole in the center arranged horizontally, and is housed in the housing chamber 45b of the casing 41 with the valve stem 49 passing through it. The spring retainer 44 is composed of a disc-shaped main body 44a with a hole 44c in the center, and a cylindrical retaining portion 44b that protrudes from the main body 44a toward the set spring 43. The spring retainer 44 is fixed to the casing 41 by tightening a bolt 52 with a height adjustment ring 51 interposed between the main body 44a and the casing 41. In this state, the retaining portion 44b abuts against the set spring 43, and the stopper 50 attached to the valve stem 49 is movably housed within the retaining portion 44b and also abuts against the set spring 43.

[0047] With the above configuration, it is possible to adjust the initial deflection and initial load (=relief pressure Prf) of the set spring 43 by changing the spring constant and number of disc springs constituting the set spring 43, the amount of advancement and retraction of the stopper 50 relative to the valve stem 49, etc. In this embodiment, for example, the initial deflection of the set spring 43 is set to 50%, and the relief pressure Prf is set to approximately 4 MPa.

[0048] Furthermore, by adjusting the thickness of the height adjustment ring 51, it is possible to restrict the maximum deflection of the set spring 43 (the maximum amount of movement of the valve body 42) and limit the range of motion of the set spring 43. For example, if the thickness of the height adjustment ring 51 is reduced, the maximum deflection of the set spring 43 decreases, and its range of motion is reduced. In this embodiment, for example, the maximum deflection of the set spring 43 is set to 75%, and as a result, the pressure inside the viscous chamber 5 at maximum deflection (the maximum value of the viscous chamber pressure) is set to approximately 6 MPa, which corresponds to a value slightly smaller than the allowable pressure of the roto-barrier seal that constitutes the sealing material 21.

[0049] When the viscous damper 1A with the above configuration is used as a vibration suppression device for a structure, it is installed between two parts of the structure that undergo relative displacement due to vibration, via first and second flange plates 15a and 15b. For example, in the example shown in Figure 5(a), the viscous damper 1A is placed within a portal frame composed of the upper and lower beams BU and BL and the left and right columns PL and PR of the structure S, and is installed between the V-shaped brace BR connected to the upper beam BU and the left and right beams PL and PR, respectively. In the example shown in Figure 5(b), the viscous damper 1A is also placed within a similar portal frame of the structure S and is installed diagonally on the diagonal brace BD extending between the corner between the upper beam BU and the right column PR and the corner between the lower beam BL and the left column PL.

[0050] In the configuration described above, when the structure S vibrates, the relative displacement between the two parts where the viscous damper 1A is installed is transmitted between the screw shaft 2a and the outer cylinder 3, and is converted into rotational motion by the ball screw 2, causing the nut member 2b and the inner cylinder 4 connected thereto to rotate relative to the outer cylinder 3. As a result, a vibration suppression effect is exerted, which suppresses the vibration of the structure S through the viscous damping effect due to the shear resistance of the viscous material VB filled in the viscous chamber 5 between the outer cylinder 3 and the inner cylinder 4.

[0051] Furthermore, if the viscous damper 1A operates for a long time in response to a long-period seismic input, for example, the shear deformation of the viscous body VB is repeated, resulting in an increase in the temperature of the viscous body VB and an increase in the pressure inside the viscous chamber 5 (hereinafter referred to as "viscous chamber pressure") due to thermal expansion. Until this viscous chamber pressure reaches the relief pressure Prf of the relief valve 33, the viscous chamber pressure remains below the initial load of the set spring 43, and the valve body 42 of the relief valve 33 is kept seated on the valve seat 46 in a closed state (state shown in Figure 4(a)), thereby maintaining a high viscous chamber pressure. This suppresses the decrease in the shear resistance of the viscous body VB due to repeated deformation and maintains the vibration suppression effect of the viscous damper 1A well.

[0052] From this state, as the viscous chamber pressure rises further and reaches the relief pressure Prf, the viscous chamber pressure overcomes the initial load of the set spring 43, compressing the set spring 43, which causes the valve body 42 to separate from the valve seat 46 and the relief valve 33 to open. As a result, the viscous body VB flows out from the viscous chamber 5 through the first communication passage 31 to the second communication passages 32, 32, and is released. In addition, a portion of the viscous chamber pressure is stored in the compressed set spring 43, and the viscous chamber pressure at this time is expressed as the sum of the relief pressure Prf (initial load of the set spring 43) and the load (reaction force) due to the compression of the set spring 43.

[0053] As the viscous chamber pressure rises further, the valve body 42 moves toward the set spring 43 (left side in Figure 4), compressing the set spring 43, thereby opening the valve. Then, as shown in Figure (b), when the stopper 50 of the relief valve 33 contacts the main body 44a of the spring retainer 44, the relief valve 33 opens completely, and the movement of the valve body 42 and the compression of the set spring 43 are restricted, causing the viscous chamber pressure to reach its maximum value (upper limit). As mentioned above, in this embodiment, this maximum value of the viscous chamber pressure is set so as not to exceed the allowable pressure of the seal material 21. Therefore, by opening the relief valve 33, the viscous chamber pressure is suppressed to below the allowable pressure of the seal material 21, thereby preventing damage to the seal material 21 and avoiding leakage of viscous material VB from the viscous chamber 5 caused by such damage.

[0054] Subsequently, as the vibration of the structure S ceases, the viscous chamber pressure decreases and falls below the relief pressure Prf, at which point the relief valve 33 closes. Also, when the viscous chamber pressure falls below the pressure in the second communication passage 32, the check valve 34 opens. As a result, the viscous body VB is returned from the second communication passage 32 to the viscous chamber 5 via the check valve 34, and the pressure in the second communication passage 32 is released into the viscous chamber 5, restoring the system to its original state.

[0055] Figure 6 shows the damping characteristics of the viscous damper 1A in response to the opening and closing of the relief valve 33 described above, as shown by the relationship between its velocity VD and damping force FD. Here, the velocity VD of the viscous damper 1A refers to, for example, the relative velocity between the upper beam BU and the lower beam BL within the structure S that is input to the viscous damper 1A, and the damping force FD of the viscous damper 1A refers to the damping force exerted by the viscous damper 1A as a whole due to the shear resistance and pressure of the viscous material VB.

[0056] As shown in the figure, until the viscous chamber pressure reaches the relief pressure Prf, the relief valve 33 remains closed and the deflection of the set spring 43 does not change, so the damping force FD of the viscous damper 1A increases in proportion to the velocity VD. When the viscous chamber pressure reaches the relief pressure Prf, the relief valve 33 opens and the viscous body VB flows out into the relief valve 33. The damping force FD at the start of opening of the relief valve 33 is called the "first relief load". Subsequently, while the relief valve 33 is open, the deflection of the set spring 43 increases, so the damping force FD rises slowly. Then, when the stopper 50 contacts the spring retainer 44, the relief valve 33 is fully open and the damping force FD becomes constant. The damping force FD in the fully open state of the relief valve 33 is called the "second relief load".

[0057] Figure 7 shows a viscous damper 1B based on a modification of the first embodiment. In this figure, the same or equivalent components as those of the viscous damper 1A in the first embodiment are denoted by the same reference numerals. This is also true for Figures 8 to 10, which show the second embodiment. As is clear from a comparison with Figure 3, the main difference between the viscous damper 1A and the viscous damper 1B is that the relief valve 33 is positioned horizontally in the viscous damper 1A, while it is positioned vertically in the viscous damper 1B.

[0058] Specifically, the relief valve 33 is positioned near the axial center of the viscous damper 1B, just above the outer cylinder 3, with the pressure-receiving chamber 45a facing downwards, extending in the vertical direction, and is fixed to the outer cylinder 3 by a stay-shaped fixing device 55. The first communication passage 31 is positioned directly below the relief valve 33 and consists of a communication hole 31a formed in the outer cylinder 3 and a communication pipe 31b connected to the communication hole 31a and communicating with the pressure-receiving chamber 45a. The pair of second communication passages 32, 32 each consist of a communication hole 32a formed at both ends of the outer cylinder 3 and an L-shaped communication pipe 32b connected to the communication hole 32a and communicating with both sides of the pressure-receiving chamber 45a.

[0059] Similar to the first embodiment, the check valve 34 is provided in the communication hole 32a of each second communication passage 32. The cover 35 is provided to cover the first and second communication passages 31, 32 and the relief valve 33. The other configurations of the viscous damper 1B are the same as those of the viscous damper 1A in the first embodiment. Therefore, the operation of the viscous damper 1B is basically the same as the operation of the viscous damper 1A described above, and the same effects as the viscous damper 1A can be obtained.

[0060] Next, a viscous damper 1C according to a second embodiment of the present invention will be described with reference to Figures 8 to 10. The viscous damper 1C is provided with an external relief mechanism 56 which includes two relief valves (first relief valve 33, second relief valve 83) and two communication passage systems (first and second communication passages 31, 32, third and fourth communication passages 81, 82) that communicate with each relief valve.

[0061] As shown in Figure 10, the first and second relief valves 33 and 83 each have the same configuration as the relief valve 33 of the first embodiment, with a pressure receiving chamber 45a formed within the casing 41 and housing the valve body 42 and set spring 43. In this embodiment, due to the difference in the setting of the set spring 43 in the first and second relief valves 33 and 83, the relief pressure (second relief pressure) Prf2 of the second relief valve 83 is set to a predetermined value that is greater than the relief pressure (first relief pressure) Prf1 of the first relief valve 33. The ends of the first and second relief valves 33 and 83 on the set spring 43 side are joined together via a partition plate 85, and they are positioned horizontally on the upper side of the outer cylinder 3 and fixed to the outer cylinder 3 by a fixing device 86.

[0062] Similar to the first embodiment, the first communication passage 31 is located near the pressure-receiving chamber 45a of the first relief valve 33 and consists of a communication hole 31a formed in the outer cylinder 3 and an L-shaped communication pipe 31b connected to the communication hole 31a and communicating with the pressure-receiving chamber 45a. The second communication passage 32 consists of a communication hole 32a formed at one end of the outer cylinder 3 and an inverted U-shaped communication pipe 32b connected to the communication hole 32a and communicating with the side of the pressure-receiving chamber 45a. A check valve 34 is provided at the lower end of the communication pipe 32b to block the flow of viscous material VB from the viscous material chamber 5 to the first relief valve 33 side.

[0063] The third and fourth communication passages 81 and 82 are configured in the same manner as the first and second communication passages 31 and 32, respectively, and are arranged symmetrically. Specifically, the third communication passage 81 is located near the pressure-receiving chamber 45a of the second relief valve 83 and consists of a communication hole 81a formed in the outer cylinder 3 and an L-shaped communication pipe 81b connected to the communication hole 81a and communicating with the pressure-receiving chamber 45a. The second communication passage 82 consists of a communication hole 82a formed at the other end of the outer cylinder 3 and an inverted U-shaped communication pipe 82b connected to the communication hole 82a and communicating with the side of the pressure-receiving chamber 45a. A second check valve 84 is provided at the lower end of the communication pipe 82b to block the flow of viscous body VB from the viscous body chamber 5 to the second relief valve 83 side. The other configurations of the viscous damper 1C are the same as those of the viscous damper 1A of the first embodiment.

[0064] With the viscous damper 1C configured as described above, for example, when the viscous chamber pressure rises due to the vibration of a structure over a long period of time, the first and second relief valves 33 and 83 are both kept closed until the first relief pressure Prf1 is reached. When the viscous chamber pressure rises further and reaches the first relief pressure Prf1, the second relief valve 83 remains closed, while the first relief valve 33 begins to open. As a result, the viscous body VB flows out from the viscous chamber 5 through the first communication passage 31 to the second communication passage 32 and is released. In addition, a portion of the viscous chamber pressure is stored in the compressed set spring 43 of the first relief valve 33. After that, the first relief valve 33 becomes fully open.

[0065] When the viscous chamber pressure rises further and reaches the second relief pressure Prf2, the second relief valve 83 begins to open. This allows the viscous material VB to flow out of the viscous chamber 5 through the third communication passage 81 to the fourth communication passage 82 and be released. In addition, a portion of the viscous chamber pressure is stored in the compressed set spring 43 of the second relief valve 83. Subsequently, the second relief valve 83 becomes fully open. Figure 10 shows the first and second relief valves 33 and 83 in the fully open state.

[0066] Subsequently, as the vibration of the structure S ceases, the viscous chamber pressure decreases and falls below the second relief pressure Prf2, at which point the second relief valve 83 closes. Also, when the viscous chamber pressure falls below the pressure in the fourth communication passage 82, the second check valve 84 opens. As a result, the viscous body VB is returned to the viscous chamber 5 from the fourth communication passage 82 via the check valve 34, and the pressure in the fourth communication passage 82 is released into the viscous chamber 5. When the viscous chamber pressure decreases further and falls below the first relief pressure Prf1, the first relief valve 33 closes. Also, when the viscous chamber pressure falls below the pressure in the second communication passage 32, the check valve 34 opens. As a result, the viscous body VB is returned to the viscous chamber 5 from the second communication passage 32 via the check valve 34, and the pressure in the second communication passage 32 is released into the viscous chamber 5, returning the system to its original state.

[0067] Figure 11 shows the damping characteristics of the viscous damper 1C in response to the opening and closing of the first and second relief valves 33 and 83 described above, in terms of the relationship between its velocity VD and damping force FD. Until the viscous chamber pressure reaches the first relief pressure Prf1, the first and second relief valves 33 and 83 are kept closed, and the deflection of their set springs 43 does not change, so the damping force FD of the viscous damper 1C increases in proportion to the velocity VD. When the viscous chamber pressure reaches the first relief pressure Prf1, the first relief valve 33 opens, and the viscous body VB flows out into the first relief valve 33. The damping force FD at the start of opening of the first relief valve 33 is called the "first relief load".

[0068] Subsequently, while the first relief valve 33 is open, the deflection of its set spring 43 increases, causing the damping force FD to rise gradually. When the first relief valve 33 is fully open, the damping force FD becomes constant. This damping force FD in the fully open state of the relief valve 33 is called the "second relief load." Subsequently, until the viscous chamber pressure reaches the second relief pressure Prf2, the second relief valve 83 remains closed, and the deflection of its set spring 43 does not change, causing the damping force FD to increase.

[0069] Subsequently, when the viscous fluid chamber pressure reaches the second relief pressure Prf2, the second relief valve 83 opens, and the viscous fluid VB flows out into the second relief valve 83. The damping force FD at the start of the opening of the second relief valve 83 is called the "third relief load." While the second relief valve 83 is open, the deflection of its set spring 43 increases, causing the damping force FD to rise gradually. Then, when the second relief valve 83 is fully open, the damping force FD becomes constant. The damping force FD in the fully open state of the second relief valve 83 is called the "fourth relief load."

[0070] As described above, according to this embodiment, by setting the second relief pressure Prf2 to a value greater than the first relief pressure Prf1, the first and second relief valves 33 and 83 open at different timings, releasing the pressure in the viscous chamber 5, thereby allowing the damping characteristics of the viscous damper 1C to be set in stages.

[0071] It should be noted that the present invention is not limited to the embodiments described and can be implemented in various forms. For example, in the second embodiment, first and second relief valves 33 and 83 are provided, and their first and second relief pressures Prf1 and Prf2 are set to different values, but they may be set to the same value. In that case, the relief function of the viscous body VB can be enhanced by having the first and second relief valves 33 and 83 open at the same timing in response to the same viscous body chamber pressure.

[0072] Alternatively, in the second embodiment, in addition to or instead of setting the relief pressure, the initial deflection and range of motion of the set spring 43 may be varied between the first and second relief valves 33 and 83. This allows for diverse settings of the damping characteristics of the viscous damper.

[0073] Furthermore, in the embodiment, a silicone oil with relatively high viscosity was used as the viscous body VB, a rotobari seal was used as the sealing material 21, and multiple disc springs were used as the set spring 43 of the relief valve 33. These are merely examples, and of course, other suitable materials may be used as long as the conditions of the present invention are met. For example, a coil spring may be used instead of a disc spring as the set spring 43.

[0074] Furthermore, although the embodiments described the target of vibration damping as primarily structures such as buildings, the present invention can be applied to any target of vibration damping as long as vibration can be suppressed by the vibration suppression device. For example, as briefly mentioned in the text, a vehicle can be used as the target of vibration damping, and vibration suppression devices can be installed as dampers to suppress vibration between parts that vibrate during operation.

[0075] Furthermore, the number and arrangement of the components of the vibration suppression device shown in the embodiments are merely examples, and may be appropriately changed depending on the size and layout of the functions required of the components. For example, in the first embodiment, the number of second connecting passages 32 is 2, but this may be increased to 3 or more, as long as space allows. In addition, the detailed configuration can be appropriately changed within the scope of the spirit of the present invention. [Explanation of Symbols]

[0076] 1A Viscous damper (vibration suppression device) according to the first embodiment 1B. Viscous damper (vibration suppression device) by modification 1C Viscous damper (vibration suppression device) according to the second embodiment 2 Ball screws 2a Screw shaft 2b Nut component (nut) 3. Outer cylinder 4 Inner cylinder 5 Viscous chamber 6. External relief mechanism 21. Sealant 31 1st communication passage 32 2nd communication passage 33. Relief valve (first relief valve) 34 Check valve 41 Casing 42 Valve body 43 Set Springs 44 Spring retainer 45a Pressure receiving chamber 49 Valve stem 50 Stoppers 51 Height adjustment ring (adjustment component) 56 External relief mechanism 81 Third communication passage 82 4th passageway 83. Second relief valve 84. Second check valve S Structure (Sectional to be seismically controlled) VB Viscous body Prf Relief Pressure Prf1 First relief pressure Prf2 Second relief pressure

Claims

1. A vibration suppression device is provided between a first part and a second part within a system including the vibration-damped object, which undergo relative displacement during vibration, in order to suppress vibrations of the vibration-damped object, A ball screw having a screw shaft connected to the first part, and a nut that is screwed onto the screw shaft via a ball and converts the linear motion of the screw shaft into rotational motion, An outer cylinder connected to the second part, An inner cylinder is coaxially arranged inside the outer cylinder, defining a viscous chamber between it and the outer cylinder, and is connected to the nut. The viscous body filled in the aforementioned viscous chamber, A sealing material for sealing the viscous body inside the viscous body chamber, It comprises an external relief mechanism for releasing the pressure inside the viscous chamber, The external relief mechanism is, One end is connected to each other at different positions in the viscous chamber, and the first and second connecting passages extend to the outside of the outer cylinder, The other ends of the first and second communication passages are connected, and a relief valve opens when the pressure inside the viscous body chamber reaches a predetermined relief pressure, releasing the pressure inside the viscous body chamber from the first communication passage to the second communication passage. A vibration suppression device characterized by having a check valve provided in the second connecting passage for preventing the flow of viscous material from the viscous material chamber to the relief valve side.

2. The vibration suppression device according to claim 1, characterized in that the second communication passage is composed of a plurality of second communication passages connected in parallel to each other between a plurality of different positions in the viscous chamber and the relief valve, and each of the plurality of second communication passages is provided with the check valve.

3. The aforementioned relief valve A casing having a pressure-receiving chamber on one end side through which the first and second connecting passages are connected, A valve body is slidably provided within the casing, which opens the pressure receiving chamber when the pressure in the viscous chamber reaches the relief pressure, thereby connecting the first communication passage and the second communication passage. A set spring provided within the casing, which biases the valve body toward the pressure receiving chamber, A spring retainer is provided on the other end side of the casing and contacts the set spring, The vibration suppression device according to claim 1 or 2, further comprising: a stopper integrally provided with the valve body, which contacts the set spring and, when the valve body opens, contacts the compression spring to limit the maximum deflection of the set spring.

4. The aforementioned set spring has a through hole, The relief valve further comprises a valve stem integrally provided with the valve body, extending through the through-hole of the set spring, and having male threads formed on its outer surface. The vibration suppression device according to claim 3, characterized in that the stopper has an internal thread formed on its inner surface and is screwed onto the valve stem so as to be able to move back and forth.

5. The vibration suppression device according to claim 3, characterized in that the relief valve further comprises an adjusting member interposed between the casing and the spring retainer for adjusting the maximum deflection of the set spring, which is limited by the stopper.

6. The vibration suppression device according to claim 3, characterized in that the pressure inside the viscous chamber when the set spring is limited to the maximum deflection is set to be less than or equal to the allowable pressure of the sealing material.

7. The aforementioned external relief mechanism is, A third and fourth connecting passage are provided separately from the first and second connecting passages, one end of which is connected to a different position in the viscous chamber, and which extend to the outside of the outer cylinder. The other ends of the third and fourth connecting passages are connected, and a second relief valve opens when the pressure inside the viscous body chamber reaches a predetermined second relief pressure, releasing the pressure inside the viscous body chamber from the third connecting passage to the fourth connecting passage. The vibration suppression device according to claim 1, further comprising a second check valve provided in the fourth communication passage for preventing the flow of viscous material from the viscous material chamber to the second relief valve side.

8. The vibration suppression device according to claim 7, characterized in that the second relief pressure of the second relief valve is set to a value greater than the relief pressure of the relief valve.

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