Structure vibration control device
A structure vibration control device includes a hydraulic damper having damping force characteristics that vary in response to a magnitude of an earthquake and having characteristics that are maintained for a long period of time regardless of an environmental temperature change. The hydraulic damper includes a preload chamber into which a high-pressure gas is charged in series with a hydraulic chamber. The preload chamber absorbs a volume change of the hydraulic chamber caused by the environmental temperature change and a piston rod and balances a bias force of a spring within the hydraulic chamber and of the preload chamber. Piston valves have high damping force characteristics against a weak earthquake and low damping force characteristics against a strong earthquake. The piston valves may include an orifice beside a check valve function, by which the high damping force characteristics lie within a range of 150 to 800 kN/(m/sec).
1. A building vibration control device comprising:
a hydraulic damper installed between a first structural member of a building and a second structural member of the building, the hydraulic damper including:
a cylinder, an end of the cylinder being connected to the first structural member;
a hydraulic chamber provided in the cylinder and filled with oil;
a piston partitioning the hydraulic chamber into a first oil chamber and a second oil chamber, and fitting movably within the cylinder;
a piston rod connected with the piston,
an end of the piston rod being connected to the second structural member;
an end member being fitted oil-tightly within the cylinder, the end member being fixed so as not to move in an axial direction of the cylinder;
a float member formed within the cylinder movably in the axial direction, the float member forming the hydraulic chamber with the end member;
a preload chamber formed between a closing portion closing the end of the cylinder and the float member, the preload chamber having a bias force counteracting a hydraulic pressure acting from the hydraulic chamber to the float member;
a first piston valve provided on one side of the piston, being normally biased to be closed, and restricting the oil from flowing from the first oil chamber to the second oil chamber, the first piston valve being closed so as to limit the oil from flowing from the second oil chamber to the first oil chamber such that a load with respect to a moving speed of the piston varies from 150 to 800 kN/(m/sec) in a state in which the moving speed of the piston within the cylinder is less than a first predetermined value, and being opened so as to permit the oil to flow from the second oil chamber to the first oil chamber in a state in which the moving speed of the piston is faster than the first predetermined value, and
a second piston valve provided on another side of the piston, being biased to be closed, and restricting the oil from flowing from the second oil chamber to the first oil chamber, the second piston valve being closed so as to limit the oil from flowing from the first oil chamber to the second oil chamber such that the load with respect to the moving speed of the piston varies from 150 to 800 kN/(m/sec) in a state in which the moving speed of the piston within the cylinder is less than a second predetermined value, and being opened so as to permit the oil to flow from the first oil chamber to the second oil chamber in a state in which the moving speed of the piston is faster than the second predetermined value.
2. The building vibration control device according to claim 1 , wherein at least one of the first piston valve and the second piston valve further includes an orifice communicating the first oil chamber and the second oil chamber,
wherein the first piston valve exhibits such damping force characteristics that the variation of the load with respect to the moving speed of the piston within the cylinder ranges from 150 to 600 kN/(m/sec) in the state in which the flow of the oil is limited in the state in which the moving speed of the piston is less than the first predetermined value, and
wherein the second piston valve exhibits such damping force characteristics that the variation of the load with respect to the moving speed of the piston within the cylinder ranges from 150 to 600 kN/(m/sec) in the state in which the flow of the oil is limited in the state in which the moving speed of the piston is less than the second predetermined value.
3. The building vibration control device according to claim 1 , wherein the piston rod extends from the piston and penetrates through only the first oil chamber in the hydraulic damper.
4. The building vibration control device according to claim 3 , wherein the hydraulic damper further includes a spring disposed within the first oil chamber through which the piston rod penetrates by being contracted between the end member and the piston.
5. The building vibration control device according to claim 1 , wherein the preload chamber is formed of a gas chamber into which inert gas with a predetermined pressure is charged.
6. The building vibration control device according to claim 1 , further comprising:
a cap member configured to close one end portion of the cylinder;
a scraper provided in the cap member to scrape adhesives attached to the piston rod; and
a spare void provided between the cap member and the end member and having a length which is longer than a stroke of the hydraulic damper.
7. The building vibration control device according to claim 2 , wherein the first piston valve includes:
an annular projection formed on one of side surfaces of the piston and formed of a circumference centering on a center axial line of the hydraulic damper;
a flexible valve seat plate biased such that an outer peripheral part thereof abuts against the annular projection; and
an oil passage communicating both side surfaces of the piston at one of an outer diameter side and an inner diameter side of the annular projection;
wherein the valve seat plate substantially abuts against the annular projection by its entire circumference and restricts the oil from flowing through the oil passage when the moving speed of the piston is the first predetermined value or less; and
wherein the valve seat plate deflects by resisting against its own bias force, separates from the annular projection at its entire circumference, and permits the oil to flow through the oil passage at once when the moving speed of the piston exceeds the first predetermined value; and
wherein the second piston valve includes:
an annular projection formed on the other of the side surfaces of the piston and formed of a circumference centering on the center axial line of the hydraulic damper;
a flexible valve seat plate biased such that an outer peripheral part thereof abuts against the annular projection; and
an oil passage communicating both side surfaces of the piston at the other of the outer diameter side and the inner diameter side of the annular projection;
wherein the valve seat plate substantially abuts against the annular projection by its entire circumference and restricts the oil from flowing through the oil passage when the moving speed of the piston is the second predetermined value or less; and
wherein the valve seat plate deflects by resisting against its own bias force, separates from the annular projection at its entire circumference, and permits the oil to flow through the oil passage at once when the moving speed of the piston exceeds the second predetermined value.
8. The building vibration control device according to claim 2 , wherein the first piston valve includes:
an annular projection formed on one of the side surfaces of the piston and formed of a circumference centering on a center axial line of the hydraulic damper;
a flexible valve seat plate biased such that an outer peripheral part thereof abuts against the annular projection; and
an oil passage communicating both side surfaces of the piston at one of an outer diameter side and an inner diameter side of the annular projection;
wherein the valve seat plate substantially abuts against the annular projection by its entire circumference and restricts the oil from flowing through the corresponding oil passage when the moving speed of the piston is the first predetermined value or less;
wherein the valve seat plate deflects by resisting against its own bias force, separates from the annular projection at its entire circumference, and permits the oil to flow through the oil passage at once when the moving speed of the piston exceeds the first predetermined value;
wherein the second piston valve includes:
an annular projection formed on the other of the side surfaces of the piston and formed of a circumference centering on the center axial line of the hydraulic damper;
a flexible valve seat plate biased such that an outer peripheral part thereof abuts against the annular projection; and
an oil passage communicating both side surfaces of the piston at the other of the outer diameter side and the inner diameter side of the annular projection;
wherein the valve seat plate substantially abuts against the annular projection by its entire circumference and restricts the oil from flowing through the oil passage when the moving speed of the piston is the second predetermined value or less; and
wherein the valve seat plate deflects by resisting against its own bias force, separates from the annular projection at its entire circumference, and permits the oil to flow through the oil passage at once when the moving speed of the piston exceeds the second predetermined value; and
wherein the orifice communicating the outer diameter side and the inner diameter side of the annular projection is formed of at least one groove cut in from the outer diameter side of at least one valve seat plate of a plurality of valve seat plates.
9. The building vibration control device according to claim 8 , wherein an opening area ratio of the orifice which is a ratio of a flow area of the orifice with respect to an inside diameter sectional area of the cylinder is in a range of 0.004 to 0.040.
10. The building vibration control device according to claim 7 , wherein each of the first piston valve and the second piston valve includes:
a boss portion formed in the piston and into which the piston rod of the piston is fittingly inserted and a hydraulic space formed on one of the side surfaces of the piston between the annular projection and the boss portion,
wherein, for each of the first piston valve and the second piston valve:
the oil passage includes one end communicating with the hydraulic space formed on the one of the side surfaces of the piston and another end communicating with the outer diameter side of the annular projection formed on the other of the side surfaces of the piston, and
a projection height of the annular projection on the corresponding side surface of the piston is heightened as compared to a projection height of the boss portion such that the valve seat plate abuts against the annular projection with a predetermined preload.
11. The building vibration control device according to claim 10 , wherein, for each of the first piston valve and the second piston valve:
at least one spacer is provided between the boss portion and the valve seat plate, and
the valve seat plate is attached to the corresponding side surface of the piston through an intermediary of the at least one spacer.
12. The building vibration control device according to claim 1 , wherein the hydraulic damper is installed aslant between the first structural member of the building and the second structural member of the building.