JP7752383B2 - Oil Damper System - Google Patents

Description

The present invention relates to an oil damper system that can improve maintainability, targeting oil dampers with variable damping performance.

To attenuate earthquake motion acting on a building supported on the ground by seismic isolation bearings, for example, between the ground and the building, oil dampers are known to absorb earthquake energy and are installed between the vibration input side and the vibration attenuation target side.

Patent Document 1 is known as an example of this type of oil damper. The "oil damper for a seismic isolation device" in Patent Document 1 is an oil damper for a seismic isolation device that, when used in combination with a seismic isolation bearing, constitutes a seismic isolation device and absorbs and attenuates the energy of earthquake shaking in order to suppress relative displacement between the foundation and the upper building during an earthquake. The oil damper comprises a first cylinder connected to one of the foundation and the upper building, a first piston slidably disposed within the first cylinder and dividing the first cylinder into two oil chambers, left and right, a first hydraulic cylinder having a pressing portion, a piston rod integrally disposed with the first piston, and connected to the other of the foundation and the upper building, a communication passage outside the first hydraulic cylinder that connects the two oil chambers to each other, a valve body disposed midway in the communication passage that opens and closes the communication passage, a movable spring seat, and a spring that is disposed between the valve body and the spring seat and biases the valve body toward the closing side. The damping valve has a spring that is inserted into the damping valve seat and a spring seat. As the first piston of the first hydraulic cylinder is displaced, the valve element opens due to hydraulic pressure supplied from the oil chamber of the first cylinder, generating a damping force. The damping valve also has a second cylinder that communicates with the back side of the spring seat of the damping valve, a second piston that is slidably disposed within the second cylinder, and a second piston rod that has an engaging portion and is integral with the second piston. When the displacement of the first piston reaches a predetermined value, the engaging portion is pressed by the pressing portion of the first piston rod, and the second hydraulic cylinder introduces hydraulic pressure from within the second cylinder to the back side of the spring seat, compressing the spring via the spring seat and increasing the spring force of the spring, thereby strengthening the damping force.

Patent No. 4442770

The oil damper disclosed in the background art introduces hydraulic pressure from within the second hydraulic cylinder to the back side of the spring seat of the damping valve when the displacement of the first piston reaches a predetermined value, increasing the spring force of the spring that biases the valve body that opens and closes the communication passage that connects to the first hydraulic cylinder, thereby strengthening the damping force. This is an excellent device that can change damping performance in response to the stroke of the first piston rod caused by seismic motion.

In this oil damper, a spring is installed inside the second cylinder, which generates hydraulic pressure that is introduced to the back side of the spring seat, and returns oil from the damping valve to the second hydraulic cylinder.

When this spring moves, the protective surface film on the inside of the second cylinder and the spring itself peels off, becoming debris that gets mixed into the oil, causing the oil to deteriorate prematurely and requiring more frequent maintenance.

In addition to incorporating a spring into the damping valve, a separate spring that returns oil is provided in the second hydraulic cylinder. Because these springs are installed in different locations, there is a concern that the maintenance work required to adjust the performance of the oil damper will be complicated.

The present invention was devised in light of the above-mentioned conventional problems, and aims to provide an oil damper system that can improve maintainability for oil dampers with variable damping performance.

The oil damper system of the present invention comprises an outer cylinder connected to one of the vibration input side and the vibration damping target side, and a piston rod connected to the other of the vibration input side and the vibration damping target side. Inside the outer cylinder, which stores hydraulic oil, there is an inner cylinder, which is partitioned into a hydraulic oil outflow chamber and a hydraulic oil inflow chamber by a piston connected to the piston rod. When the piston reciprocates, hydraulic oil in the hydraulic oil outflow chamber flows out into the outer cylinder and flows in one direction from the outer cylinder to the hydraulic oil inflow chamber. A uniflow type cylinder unit has a valve body biased by a spring member, and hydraulic oil flowing from the hydraulic oil outflow chamber to the outer cylinder moves the valve body against the spring force, thereby absorbing energy. A transmission member transmits the extension/retraction stroke amount of the piston rod that moves the piston, and a transmission member is provided along the extension/retraction stroke direction of the piston rod, and the transmission member is provided along the extension/retraction stroke direction of the piston rod. When an excessive extension stroke or excessive retraction stroke occurs in the piston rod that exceeds the predetermined extension/retraction stroke amount, the transmission member causes each control piston rod to extend by the excessive extension stroke amount or excessive retraction stroke amount, thereby discharging control oil; and a control oil supply system supplies the control oil discharged from each of the pair of control cylinder units to the damping valve unit. The damping valve unit is characterized by the following: a spring seat is provided on the opposite side of the valve body across the spring member, and is moved so as to compress the spring member by control oil supplied from the control oil supply system, increasing the spring force of the spring member according to the excessive extension stroke amount and excessive retraction stroke amount; and return means for returning control oil to each of the control cylinder units to return each of the control piston rods to their initial positions.

The return means is characterized in that the spring member is set to a spring force that presses against the spring seat so as to cause the control oil to flow into the control oil supply system.

The return means is a shim that is provided between the spring seat and the valve body, overlapping the spring member, and causes the spring member to press the spring seat so as to allow the control oil to flow into the control oil supply system.

The return means is a return spring formed with a spring constant smaller than that of the spring member, arranged in parallel with the spring member between the spring seat and the valve body, and pressing the spring seat from the valve body side so as to cause the control oil to flow into the control oil supply path.

The return means is characterized by returning control oil to each of the control cylinder units when the flow of hydraulic oil that moves the valve body ceases.

The oil damper system of the present invention can improve maintainability for oil dampers that have variable damping performance.

1 is an explanatory diagram illustrating a hydraulic circuit of a preferred embodiment of an oil damper system according to the present invention. FIG. FIG. 2 is a plan view showing the device configuration of the oil damper system of FIG. 1 in an installed state. FIG. 2 is a side view showing the device configuration of the oil damper system of FIG. 1 in an installed state. FIG. 2 is a cross-sectional view illustrating a damping valve unit provided in the oil damper system of FIG. 1 . FIG. 2 is a cross-sectional view illustrating a control cylinder unit provided in the oil damper system of FIG. 1. FIG. 5 is a cross-sectional view showing a modified example of the damping valve unit shown in FIG. 4 . FIG. 5 is a cross-sectional view showing another modified example of the damping valve unit shown in FIG. 4 .

Below, a preferred embodiment of the oil damper system of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 is an explanatory diagram illustrating the hydraulic circuit of the oil damper system according to this embodiment. Figure 2 is a diagram illustrating a plan view of the device configuration of the oil damper system of Figure 1 in an installed state. Figure 3 is a diagram illustrating a side view of the device configuration of the oil damper system of Figure 1 in an installed state. Figure 2 may be a side view of the installed state, and Figure 3 may be a plan view of the installed state.

The oil damper system 1 in this embodiment is installed between the vibration input side and the vibration damping target side, for example, between the foundation of the ground 2 or the building 3 that moves integrally with the ground 2 to absorb earthquake energy, and the building 3 supported on the foundation by seismic isolation bearings.

However, it goes without saying that the oil damper system 1 according to this embodiment can be installed in any vibration transmission system for the purpose of vibration damping.

The oil damper system 1 in this embodiment is primarily composed of a uniflow-type cylinder unit 4.

The uniflow cylinder unit 4 itself is known and comprises an outer cylinder 5, a hydraulic oil reservoir 6 disposed within the outer cylinder 5 and storing hydraulic oil F with a free surface, an inner cylinder 7 disposed within the outer cylinder 5, a piston 8 slidably disposed within the inner cylinder 7 in a liquid-tight manner and dividing the interior of the inner cylinder 7 into two hydraulic oil outlet chambers R1 and R2, a piston rod 9 integrally connected to the piston 8, which penetrates the inner cylinder 7 and protrudes liquid-tightly outward from the outer cylinder 5, and is slidably operable, a first damper check valve 11 disposed between the hydraulic oil reservoir 6 and the hydraulic oil inlet chamber R2 and allows hydraulic oil F to flow only from the hydraulic oil reservoir 6 to the hydraulic oil inlet chamber R2 and blocks backflow, and a second damper check valve 12 disposed on the piston 8 and allows hydraulic oil F to flow only from the hydraulic oil inlet chamber R2 to the hydraulic oil outlet chamber R1 and blocks backflow.

In the uniflow type cylinder unit 4, when the piston 8 reciprocates, the hydraulic oil in the hydraulic oil outlet chamber R1 flows out into the outer cylinder 5, and at the same time, hydraulic oil flows from the outer cylinder 5 into the hydraulic oil inlet chamber R2, so that the hydraulic oil flows in one direction.

The pressure-receiving area of the piston 8 on the hydraulic oil outflow chamber R1 side to which the piston rod 9 is connected is set to half the cross-sectional area of the hydraulic oil inflow chamber R2 side, minus the cross-sectional area of the piston rod 9.

The oil damper system 1 is basically constructed by providing a damping valve unit 10 that generates energy absorption between the hydraulic oil outflow chamber R1 of the cylinder unit 4 and the hydraulic oil reservoir 6 in the outer cylinder 5.

As shown in Figure 4, the damping valve unit 10 is composed of a valve body 13 having a hydraulic oil inlet port P1 that communicates with the hydraulic oil outlet chamber R1 of the inner cylinder 7 and a hydraulic oil outlet port P2 that communicates with the hydraulic oil reservoir 6; a valve element 14 that is movably mounted within the valve body 13 and moves to open and close the hydraulic oil inlet port P1; a spring seat 15 that is positioned within the valve body 13 on the opposite side from the valve element 14 and is movably mounted in a liquid-tight manner relative to the valve body 13; and a pressure adjustment spring 16 that is sandwiched within the valve body 13 between the spring seat 15 and the valve element 14 and is supported by the spring seat 15 to bias the valve element 14.

That is, the valve body 14 is disposed at one end of the pressure adjustment spring 16, and the spring seat 15 is disposed at the other end of the pressure adjustment spring 16.

In the damping valve unit 10, the pressure regulating spring 16 biases the valve element 14 toward the hydraulic oil inlet port P1. The biasing force of the pressure regulating spring 16 causes the valve element 14 to close the hydraulic oil inlet port P1, thereby isolating the hydraulic oil outlet chamber R1 from the hydraulic oil reservoir 6. On the other hand, the valve element 14 opens the hydraulic oil inlet port P1 against the biasing force of the pressure regulating spring 16, thereby connecting the hydraulic oil inlet port P1 to the hydraulic oil outlet port P2, thereby connecting the hydraulic oil outlet chamber R1 to the hydraulic oil reservoir 6.

In the damping valve unit 10, hydraulic oil is pushed by the piston 8 and flows from the hydraulic oil outflow chamber R1 toward the outer cylinder 5. This causes the valve element 14 to move against the spring force of the pressure regulating spring 16, opening the hydraulic oil inlet port P1, causing a pressure loss in the hydraulic oil and absorbing energy.

The valve body 13 of the damping valve unit 10 is further provided with an inlet port P3 (described below) facing the back surface of the spring seat 15 (the side opposite to the side where the pressure adjustment spring 16 is installed).

The uniflow type cylinder unit 4 operates when the piston rod 9 is pulled out from the outer cylinder 5 in the protruding direction and the piston 8 moves to narrow the hydraulic oil outflow chamber R1 of the inner cylinder 7, causing hydraulic oil F to flow out of the hydraulic oil outflow chamber R1 toward the damping valve unit 10.

The outflow pressure of the hydraulic oil F flowing out of the hydraulic oil outflow chamber R1 acts on the hydraulic oil inlet port P1, moving the valve element 14, which is biased by the pressure regulating spring 16, against the spring force of the pressure regulating spring 16, thereby opening the hydraulic oil inlet port P1.

When the hydraulic oil inlet port P1 is opened, hydraulic oil F flows through the valve body 13 of the damping valve unit 10, through the gap between the inner surface of the valve body 13 and the valve element 14, toward the hydraulic oil outlet port P2, and then from the hydraulic oil outlet port P2 toward the hydraulic oil reservoir 6.

In the damping valve unit 10, the pressure regulating spring 16 limits the opening of the valve body 14 due to the outflow pressure of the hydraulic oil F from the hydraulic oil outflow chamber R1. In other words, by allowing the hydraulic oil F to continue to flow while maintaining the compressed state of the pressure regulating spring 16, the energy absorption function of the oil damper system 1 is exerted.

When the hydraulic oil outflow chamber R1 is narrowed and hydraulic oil F flows out of the hydraulic oil outflow chamber R1, hydraulic oil F flows into the hydraulic oil inflow chamber R2, which is widened, from the hydraulic oil reservoir 6 via the first damper check valve 11.

On the other hand, when the piston rod 9 is pushed in the retracting direction toward the outer cylinder 5 and the piston 8 moves to expand the hydraulic oil outflow chamber R1 of the inner cylinder 7, thereby narrowing the hydraulic oil inflow chamber R2, because the first damper check valve 11 is closed and, as described above, the pressure-receiving area on the hydraulic oil inflow chamber R2 side of the piston 8 is twice the pressure-receiving area on the hydraulic oil outflow chamber R1 side, the pressurized hydraulic oil F in the hydraulic oil inflow chamber R2 is sent through the piston 8's second damper check valve 12 into the hydraulic oil outflow chamber R1 in an amount twice that when the piston rod 9 extended, and half of that amount of hydraulic oil F is further pushed out of the hydraulic oil outflow chamber R1 and flows out toward the damping valve unit 10.

When twice the amount of hydraulic oil F flows into the hydraulic oil inlet chamber R2, half the amount of hydraulic oil F is replenished and the hydraulic oil outlet chamber R1 is always filled.

When the piston rod 9 is retracted, just as when it is extended, the outflow pressure of the hydraulic oil F flowing out of the hydraulic oil outflow chamber R1 acts on the hydraulic oil inlet port P1, moving the valve element 14, which is biased by the pressure regulating spring 16, against the spring force of the pressure regulating spring 16, thereby opening the hydraulic oil inlet port P1.

When the hydraulic oil inlet port P1 is opened, hydraulic oil F flows through the valve body 13 of the damping valve unit 10 toward the hydraulic oil outlet port P2, and then flows from the hydraulic oil outlet port P2 toward the hydraulic oil reservoir 6.

In the damping valve unit 10, even when the piston rod 9 is retracted, the pressure regulating spring 16 limits the opening of the valve body 14 due to the outflow pressure of the hydraulic oil F from the hydraulic oil outflow chamber R1. In other words, by maintaining the compressed state of the pressure regulating spring 16 while allowing the hydraulic oil F to continue to flow, the energy absorption function of the oil damper system 1 is exerted.

When the piston rod 9 extends or retracts, if the sliding distance of the piston 8 is the same, the amount of hydraulic oil F flowing into the damping valve unit 10 will be the same, and therefore the amount of energy absorption will be the same.

In the uniflow type cylinder unit 4 that constitutes the oil damper system 1 according to this embodiment, as described above, the hydraulic oil F flows in one direction, flowing only from the hydraulic oil outflow chamber R1 toward the hydraulic oil reservoir 6 and only from the hydraulic oil reservoir 6 into the hydraulic oil inflow chamber R2.

A relief valve 17 is provided between the hydraulic oil outflow chamber R1 and the hydraulic oil reservoir 6 to release and control the hydraulic pressure of the hydraulic oil F in the hydraulic oil outflow chamber R1 when the piston rod 9 operates at high speed.

The outer cylinder 5 of the cylinder unit 4 is connected to one of the vibration input side and the vibration damping target side, for example, the ground 2.

The piston rod 9 of the cylinder unit 4 is also connected to the other of the vibration input side and the vibration damping target side, for example, the building 3.

The cylinder unit 4 is installed by connecting it to, for example, the ground 2 and the building 3, and as shown in Figures 2 and 3, attachment portions 37 for these objects are provided on the piston rod 9 and outer cylinder 5 of the cylinder unit 4.

In addition, a bellows 51 that can expand and contract in response to the extension and contraction stroke of the piston rod 9 is provided between the outer cylinder 5 and the mounting portion 37 as a cover that externally covers the transmission member 18.

When an earthquake causes relative displacement between the ground 2 and the building 3, the piston rod 9 of the cylinder unit 4 itself moves forward or backward by a stroke amount corresponding to the amount of relative displacement.

In this specification, the "extension/retraction stroke of the piston rod 9" refers to the change in length of the cylinder unit 4, which occurs when the piston rod 9 is pulled outward from the outer cylinder 5 and inner cylinder 7 in a protruding direction or pushed inward in a retracted direction, accompanying the reciprocating movement of the piston 8, causing the length dimension of the cylinder unit 4 to increase or decrease in the length direction of the piston rod 9.

Similarly, the "extending stroke of the piston rod 9" refers to the change in the length of the cylinder unit 4 as it lengthens in the longitudinal direction of the piston rod 9, and the "retracting stroke of the piston rod 9" refers to the change in the length of the cylinder unit 4 as it shortens in the longitudinal direction of the piston rod 9.

These strokes represent the displacement of the cylinder unit 4 from its inoperative state, in which the piston rod 9 is stopped in its initial position.

Furthermore, "protruding" the piston rod 9 means that, as the piston 8 reciprocates, the piston rod 9 is pulled outward from the outer cylinder 5 and inner cylinder 7, increasing the length of the cylinder unit 4 in the direction of the piston rod 9; "retracting" the piston rod 9 means that the piston rod 9 is pushed inward into the outer cylinder 5 and inner cylinder 7, decreasing the length of the cylinder unit 4 in the direction of the piston rod 9.

As shown in Figures 1 to 3, the cylinder unit 4 is provided with a transmission member 18 that transmits the extension/retraction stroke amount of the piston rod 9 that moves the piston 8.

The transmission member 18 is formed as a shaft that is long in the direction of the extension/retraction stroke of the piston rod 9. The base end 18a, which is one longitudinal end of the transmission member 18, is attached to the piston rod 9, and the tip end 18b, which is the other longitudinal end, is supported movably on the outside of the outer cylinder 5.

The transmission member 18, whose base end 18a is attached to the piston rod 9, slides outside the cylinder unit 4 in accordance with the extension and retraction of the piston rod 9. When the piston rod 9 performs a protruding stroke, the tip 18b moves the same distance in the direction of the protruding stroke, and when the piston rod 9 performs a retracting stroke, the tip 18b moves the same distance in the direction of the retracting stroke.

A pair of control cylinder units 19, 19 are provided on the outside of the outer cylinder 5 of the cylinder unit 4, on either side of the transmission member 18, along the extension/retraction stroke direction of the piston rod 9.

One control cylinder unit 19 is configured to operate for the extension stroke of the piston rod 9, and the other control cylinder unit 19 is configured to operate for the retraction stroke.

As shown in Figure 5, each of these control cylinder units 19, 19 comprises a cylinder case 20, a control piston 21 that is slidably mounted in an airtight manner within the cylinder case 20 and divides the interior of the cylinder case 20 into an oil chamber 20a filled with control oil f and an air chamber 20c that is maintained at atmospheric pressure through an air hole 20b provided in the cylinder case 20, and a control piston rod that is slidably movable in and out of the cylinder case 20, with one end connected to the control piston 21 from the oil chamber 20a side and the other end protruding fluid-tightly outside the cylinder case 20. 22, and a control oil inlet/outlet port P4 that is provided in the cylinder case 20 and discharges control oil f from the oil chamber 20a, which is narrowed by the control piston 21 that slides when the control piston rod 22 protrudes, toward the damping valve unit 10.As will be described later, when the cylinder unit 4 finishes operating and enters a non-operating state, control oil f returned from the damping valve unit 10 flows into the oil chamber 20a, narrowing the air chamber 20c and pushing back the control piston 21 together with the control piston rod 22.

In this specification, "the control piston rod 22 protrudes or retracts" refers to the change in length of the control cylinder unit 19 becoming longer or shorter in the length direction of the control piston rod 22, as the control piston 21 reciprocates and the control piston rod 22 is pulled out in a direction protruding outward from the cylinder case 20 or pushed in in a direction retracting inward.

An operating part 24 is provided at the tip 18b of the transmission member 18, and a passive part 25, with which the operating part 24 can be freely engaged and disengaged, is provided at the protruding tip of the other end of the control piston rod 22 of the pair of control cylinder units 19 on both sides of the transmission member 18.

As shown in Figures 1 and 2, the pair of control cylinder units 19, 19 are installed so that their control piston rods 22, 22 protrude in opposite directions, and so that the operating portion 24 of the transmission member 18 is located between their passive portions 25, 25 in the extension/retraction stroke direction of the piston rod 9.

Furthermore, when the piston rod 9 of the cylinder unit 4 is in a neutral position in the direction of extension and retraction stroke (in other words, when the cylinder unit 4 is in its initial, non-operating state), and the air chamber 20c is narrowed and the extension stroke of the control piston rods 22 is positioned at its initial position of "0," the passive parts 25, 25 of these control cylinder units 19, 19 are spaced apart from the operating part 24 by a distance equal to the predetermined extension and retraction stroke set for the piston rod 9.

The predetermined extension/retraction stroke amount refers to the extension stroke amount S and retraction stroke amount S that are set equal in the extension stroke direction and retraction stroke direction, respectively, based on the neutral position N of the piston rod 9, as shown in Figure 1.

In other words, the actuating part 24 and each of the passive parts 25, 25 are equally spaced apart by a distance equal to the predetermined stroke amount S of the piston rod 9.

When the piston rod 9 extends or retracts within the specified stroke amount S, the operating portion 24 of the transmission member 18 moves accordingly, but the operating portion 24 does not engage with the passive portion 25 of any of the control cylinder units 19, and the control cylinder units 19 are not operated.

When the piston rod 9 experiences an excessive extension stroke, such as an excessive extension stroke, that exceeds the predetermined extension/retraction stroke amount S, the actuating portion 24 engages with the passive portion 25 of the control piston rod 22 of one of the control cylinder units 19.

The passive part 25 then causes the control piston rod 22 to protrude by an excess protrusion stroke amount that exceeds the specified protrusion/retraction stroke amount S.

The control piston rod 22 is extended, causing the control piston 21 to slide, and control oil f is discharged from the inlet/outlet port P4 of the cylinder case 20 for the excess extension stroke.

When the piston rod 9, which repeats its extending and retracting strokes, transitions to its retracting stroke, the actuating portion 24 of the transmission member 18 disengages from the passive portion 25, which engaged with the piston rod 22 to cause it to extend.

If the excess protrusion stroke amount during the next protrusion stroke does not exceed the previous excess protrusion stroke amount, the control piston rod 22 that had been protruding during that time will remain in the same position and no control oil f will be discharged. However, if the excess protrusion stroke amount exceeds the previous excess protrusion stroke, the operating part 24 will again engage with the passive part 25, causing the control piston rod 22 to protrude again by the newly increased excess protrusion stroke amount, resulting in the control cylinder unit 19 discharging control oil f in an amount corresponding to the increased excess protrusion stroke.

When an excessive retraction stroke occurs in the piston rod 9 that exceeds the specified extension/retraction stroke, the operating part 24 of the transmission member 18 causes the control piston rod 22 of the other control cylinder unit 19 to extend in the same manner as the control piston rod 22 of the one control cylinder unit 19 described above, and control oil f equal to the excess retraction stroke, and also equal to the increase in the excess retraction stroke, is discharged from the inlet/outlet port P4 of the cylinder case 20.

In this way, when the extension/retraction stroke amount of the piston rod 9 of the cylinder unit 4 exceeds the predetermined extension/retraction stroke amount S, the control cylinder unit 19 first discharges control oil f for the excess extension/retraction stroke amount when it exceeds the predetermined extension/retraction stroke amount S, and then repeats this process of discharging control oil f for the excess extension/retraction stroke amount that exceeds the previous excess extension/retraction stroke amount.

In other words, when the pair of control cylinder units 19, 19 exceeds the predetermined extension/retraction stroke amount S, and thereafter, each time the excess extension/retraction stroke amount increases, an increased amount of control oil f is discharged.

As shown in Figures 1 to 3, a control oil supply system 26 is provided between the pair of control cylinder units 19, 19 and the damping valve unit 10.

The control oil supply system 26 is composed of a piping system and has a communication section 27 that connects the inlet/outlet ports P4, P4 of a pair of control cylinder units 19, 19, and also connects the communication section 27 to the inlet port P3 of the damping valve unit 10.

A check valve 28 is provided in the control oil supply system 26, positioned between the communication portion 27 and the inlet port P3 of the damping valve unit 10.

The check valve 28 allows control oil f to flow from the communication portion 27 toward the inlet port P3, preventing backflow.

Then, control oil f flows into the valve body 13 from the inlet port P3, generating hydraulic pressure on the back surface of the spring seat 15, which acts as back pressure on the check valve 28.

Unlike the valve element 14, the spring seat 15 is provided in a liquid-tight manner and is freely movable relative to the valve body 13.

As a result, the control oil f that flows in from the inlet port P3 presses and displaces the spring seat 15, remaining inside the valve body 13. As a result, the control oil f does not mix with the hydraulic oil F and flow from the hydraulic oil outlet port P2 into the hydraulic oil reservoir 6.

In other words, in the control oil supply system 26 equipped with the check valve 28, the control oil f discharged from each of the inlet/outlet ports P4, P4 flows back and forth between these pairs of inlet/outlet ports P4, P4, and also flows through the check valve 28 and the inlet port P3 to the back surface of the spring seat 15 in the damping valve unit 10, generating oil pressure at the back surface of the spring seat 15 that changes the spring force of the pressure regulating spring 16.

The piston rod 9 of the cylinder unit 4 alternately extends and retracts, causing the control piston rods 22, 22 of the pair of control cylinder units 19, 19 to alternately extend, causing control oil f to be intermittently discharged alternately from each inlet/outlet port P4, P4.

The check valve 28 introduces control oil f into the inlet/outlet port P3 when the oil pressure of the control oil f discharged from the inlet/outlet port P4 of one of the control cylinder units 19 during the protruding operation and acting through the communication part 27 exceeds the valve opening pressure. On the other hand, when the oil pressure of the control oil f is below the valve opening pressure, the check valve 28 prevents the control oil f from flowing into the inlet port P3.

The control oil f, whose flow is blocked by the check valve 28, flows through the communication section 27 into the inlet/outlet port P4 of the other control cylinder unit 19 (where no hydraulic pressure is generated in the oil chamber 20a and the control piston rod 22 can move toward the air chamber 20c).

This communication section 27 functions as a relief circuit when the control oil f cannot pass through the check valve 28, such as when the hydraulic pressure generated behind the spring seat 15 (the back pressure of the check valve 28) reaches the set upper limit.

When an excessive extension stroke and an excessive retraction stroke occur, the pair of control cylinder units 19, 19 alternately extend and retract each time the stroke increases. The hydraulic pressure of the control oil f generated by these units repeatedly acts on the check valve 28, and the check valve 28 allows the control oil f to flow into the inlet port P3 of the damping valve unit 10 each time the pressure exceeds the valve opening pressure.

As a result, within the valve body 13 of the damping valve unit 10, the control oil f is introduced from the inlet port P3 to the back surface of the spring seat 15, and the gradually increasing amount of control oil f causes the pressure adjustment spring 16 to gradually contract between itself and the valve body 14. This contraction increases the spring force of the pressure adjustment spring 16 that biases the valve body 14.

In other words, the spring seat 15 is moved so as to compress the pressure adjustment spring 16 by the hydraulic pressure of the control oil f introduced from the inlet port P3, thereby causing the spring force of the pressure adjustment spring 16 to change according to the amount of excess protruding stroke or excess retracting stroke.

As shown in Figure 1, the control oil supply system 26 is provided with a bypass path 29 that bypasses the check valve 28 to return the control oil f to the pair of control cylinder units 19, 19. This bypass path 29 is provided with a return valve (e.g., a needle valve) 30, which has a throttling function that allows it to be freely opened and closed and its opening to be freely adjusted, in parallel with the check valve 28.

This return valve 30 opens, for example, when an earthquake subsides and the cylinder unit 4 ceases operation and enters a deactivated state (the piston rod 9 returns to the neutral position N in the extension/retraction stroke direction), and sequentially returns the control oil f sent to the damping valve unit 10 from the inlet port P3 via the communication section 27 to the inlet/outlet ports P4, P4 of the pair of control cylinder units 19, 19.

On the other hand, the return valve 30 limits the outflow of control oil f from the back surface of the spring seat 15 while the cylinder unit 4 is operating.

In the oil damper system 1 according to this embodiment, unlike the background art, the damping valve unit 10 is provided with return means for returning the control oil F from the damping valve unit 10 to the inlet/outlet ports P4, P4 of each control cylinder unit 19, 19 in order to return each control piston rod 22, 22 to its initial position where the protruding stroke amount is "0" when, for example, an earthquake subsides as described above, the cylinder unit 4 ceases operation and enters a non-operating state, eliminating the flow of hydraulic oil F that moves the valve body 14.

In the example of the damping valve unit 10 shown in Figure 4, the return means is configured so that the pressure regulating spring 16 is set to a spring force that presses the spring seat 15 so that the control oil f flows out into the control oil supply system 26.

In other words, when the cylinder unit 4 transitions from an operating state to a non-operating state, only a slight hydraulic pressure acts on the valve body 14 of the damping valve unit 10 at the hydraulic oil inlet port P1, which is connected to the hydraulic oil outlet chamber R1, and the operating portion 24 does not engage with the passive portion 25 to cause the control piston rod 22 to protrude.

At this time, as the pressure regulating spring 16 expands from its compressed state due to the control oil f via the spring seat 15 and returns to its original state, it presses against the spring seat 15 to block the inlet port P3, and pushes almost all of the control oil f from the valve body 13 back through the return valve 30 to the control oil supply system 26 and ultimately to the inlet/outlet port P4 of each control cylinder unit 19, 19.

It is desirable that the spring force of the pressure regulating spring 16 be such that when the cylinder unit 4 is in an inoperative state and the flow of hydraulic oil F has ceased, the control oil F gradually flows out and is returned to the control oil supply system 26.

The pressure adjustment spring 16 should be installed so that the valve body 14 can close the hydraulic oil inlet port P1 and the spring seat 15 can close the introduction port P3, and so that no or only a small deformation load is applied to the pressure adjustment spring 16.

In Figure 1, reference numeral 31 denotes a hydraulic pressure gauge that displays the hydraulic pressure within the control oil supply system 26, and reference numeral 32 denotes an on-off valve for draining the control oil f.

The operation of the oil damper system 1 according to this embodiment will now be described. The cylinder unit 4 is set between the ground 2 and the building 3 with the piston rod 9 in the neutral position N in the extension/retraction stroke direction.

For example, when an earthquake occurs and the cylinder unit 4 begins to operate, if the piston rod 9 does not have an excessive protruding stroke or excessive retracting stroke, the pair of control cylinder units 19, 19 will not be operated, and the cylinder unit 4 will absorb earthquake energy by opening and closing the valve body 14 of the damping valve unit 10 in response to the outflow pressure of the hydraulic oil F with the initial spring characteristics set in the pressure regulating spring 16.

When the piston rod 9 experiences an excess extension/retraction stroke amount exceeding the predetermined extension/retraction stroke amount S, the control cylinder units 19, 19 are actuated by the actuating portion 24 of the transmission member 18.

When the control piston rod 22 of one of the control cylinder units 19 is extended by either the initial excessive extension stroke or excessive retraction stroke, and control oil F is introduced from the inlet/outlet port P4 through the check valve 28 to the back surface of the spring seat 15 of the damping valve unit 10, the pressure regulating spring 16 is compressed. As a result, the damping valve unit 10 opens and closes the valve body 14 against the outflow pressure of the hydraulic oil F due to the spring characteristics of the pressure regulating spring 16, which have been changed to a spring force greater than the initial spring characteristics, thereby increasing the absorption of earthquake energy.

When the excess extension/retraction stroke is within the initial excess extension/retraction stroke amount and does not exceed that amount, the pair of control piston rods 19, 19 are not further extended by the transmission member 18.

On the other hand, whenever an excess protruding stroke or excess retracting stroke occurs that exceeds the previous excess protruding/retracting stroke, the check valve 28 is opened by the hydraulic pressure of the control oil f discharged from each of the pair of control cylinder units 19, 19, and each time this occurs, the control oil f is introduced into the damping valve unit 10, causing the spring force of the pressure regulating spring 16 to change increasingly significantly.

Therefore, the greater the extension/retraction stroke of the piston rod 9 caused by an earthquake, the greater the spring force of the pressure regulating spring 16 of the damping valve unit 10 can be, resulting in a significant change in energy absorption performance.

After that, for example, when the earthquake subsides and the cylinder unit 4 ceases operation and enters a deactivated state (the piston rod 9 returns to the neutral position N in the extending/retracting stroke direction), the pressure regulating spring 16 in the damping valve unit 10, which had been in a compressed state until then, begins to expand and elastically restore itself, with the valve body 14 as the base point. This presses the spring seat 15 toward the inlet port P3, allowing the control oil f introduced into the valve body 13 to gradually return to the control oil supply system 26.

In the control oil supply system 26, control oil f flows from the bypass path 29 through the return valve 30 into the communication section 27, and is then returned to the oil chambers 20a, 20a through the inlet/outlet ports P4, P4 of each control cylinder unit 19, 19. This causes the control pistons 21, 21 to slide to narrow the air chambers 20c, 20c, and the control cylinder rods 22, 22 are retracted into the cylinder cases 20, 20, returning the control cylinder units 19, 19 to their initial state.

In the oil damper system 1 of this embodiment, when the flow of hydraulic oil F that moves the valve body 14 ceases, the damping valve unit 10 is provided with a return means configured as a pressure regulating spring 16 that returns the control oil f to each of the control cylinder units 19, 19 in order to return each of the control piston rods 22, 22 to their initial positions. Therefore, there are no locations where foreign matter such as dust can get mixed into the control oil f between the control cylinder unit 19 and the control oil supply system 26, where the control oil f flows, preventing early deterioration of the control oil f.

In addition, by providing the damping valve unit 10 with the return means as the pressure adjustment spring 16, maintenance work related to the spring characteristics for adjusting performance can be performed on the damping valve unit 10 alone.

This improves the maintainability of the oil damper system 1.

The control oil supply system 26 is provided with a bypass path 29 that bypasses the check valve 28. The bypass path 29 is provided with a return valve 30 in parallel with the check valve 28, which sequentially returns the control oil f from the inlet port P3 of the damping valve unit 10 to the inlet/outlet ports P4, P4 of the pair of control cylinder units 19, 19 via the communication section 27. This allows the cylinder unit 4 and the pair of control cylinder units 19, 19 to smoothly return to their pre-operation neutral state after an earthquake has subsided, for example.

Figure 6 shows a modified version of the above embodiment. In this modified version, the return means is comprised of a shim 33 that is provided between the spring seat 15 and the valve body 14, overlapping the pressure regulating spring 16, and causes the pressure regulating spring 16 to press against the spring seat 15 so that the control oil f flows into the control oil supply system 26.

The shim 33 is a well-known component used for adjusting gaps. By placing this shim 33 on top of the pressure regulating spring 16 and performing fine adjustments, the initial spring characteristics of the pressure regulating spring can be set or changed by adjusting the thickness of the shim 33, without having to change to a pressure regulating spring 16 with different spring characteristics. This allows the control oil f to be appropriately returned to the control oil supply system 26, returning the control cylinder unit 19 to its initial state.

In the illustrated example, three shims 33 are stacked between the valve body 14 and the pressure adjustment spring 16, but they may also be placed between the spring seat 15 and the pressure adjustment spring 16, and the number of shims is not important.

The shim 33 may be provided in combination with the pressure adjustment spring used as the return means in the above embodiment. Naturally, this modification will achieve the same effects as the above embodiment.

Figure 7 shows another modified example of the above embodiment. In this modified example, the return means is formed with a spring constant smaller than that of the pressure adjustment spring 16, and is composed of a return spring 34 that is provided in parallel with the pressure adjustment spring 16 between the spring seat 15 and the valve body 14 and presses the spring seat 15 from the valve body 14 side so as to cause the control oil f to flow into the control oil supply path 26.

The return spring 34 has a spring constant smaller than that of the pressure adjustment spring 16, i.e., a weaker spring force, so as not to interfere with the independent energy absorption function of the pressure adjustment spring 16.

While the cylinder unit 4 is operating, the return spring 34 expands and contracts almost independently of the action of the pressure adjustment spring 16. However, after the cylinder unit 4 has ceased operation and is deactivated, for example after an earthquake has subsided, the spring seat 15, which is returned by the elastic restoration of the pressure adjustment spring 16, has not yet returned to a position that completely blocks the inlet port P3. Therefore, the control piston rod 22 has not yet returned completely to its original position. In this state, the return spring 34 gradually presses the spring seat 15 toward the inlet port P3 with a weak spring force, appropriately returning the control oil f to the control oil supply system 26 and returning the control cylinder unit 19 to its initial state.

The return spring 34 may be provided in combination with the pressure adjustment spring 16, which serves as the return means in the above embodiment, or may be combined with the shim 33. Naturally, even with such a modification, the same effects as those of the above embodiment can be achieved.

The return valve 30 may be configured to allow a small amount of control oil f to flow at all times, so that even while control oil f is flowing toward the inlet port P3, this small amount is returned to the control cylinder unit 19.

It is desirable to set this minute amount so that all of the control oil f can be returned to the control cylinder unit 19 in a short time, for example, 5 to 10 minutes after the earthquake has subsided, and so that appropriate oil pressure can be generated within the valve body 13 when the oil damper system 1 is operating.

REFERENCE SIGNS LIST 1 Oil damper system 2 Ground 3 Building 4 Uniflow type cylinder unit 5 Outer cylinder 7 Inner cylinder 8 Piston 9 Piston rod 10 Damping valve unit 14 Valve body 15 Spring seat 16 Pressure regulating spring 18 Transmission member 19 Control cylinder unit 22 Control piston rod 26 Control oil supply system 33 Shim 34 Return spring F Hydraulic oil f Control oil S Specified amount of rise and fall stroke R1 Hydraulic oil outflow chamber R2 Hydraulic oil inflow chamber

Claims (5)

a uniflow type cylinder unit in which an outer cylinder is connected to one of the vibration input side and the vibration damping target side, and a piston rod is connected to the other of the vibration input side and the vibration damping target side, and an inner cylinder is provided inside the outer cylinder in which hydraulic oil is stored, and an hydraulic oil outflow chamber and a hydraulic oil inflow chamber are partitioned by a piston to which the piston rod is connected, and when the piston reciprocates, the hydraulic oil in the hydraulic oil outflow chamber flows out into the outer cylinder and flows in one direction from the outer cylinder to the hydraulic oil inflow chamber;
a damping valve unit having a valve body biased by a spring member, wherein the hydraulic oil flowing from the hydraulic oil outflow chamber to the outer cylinder moves the valve body against the spring force, thereby absorbing energy;
a transmission member that transmits a stroke amount of the piston rod that moves the piston;
a pair of control cylinder units respectively provided along the extending/retracting stroke direction of the piston rods, and when an excessive protruding stroke or excessive retracting stroke exceeding a predetermined extending/retracting stroke occurs in the piston rods, the control piston rods are respectively extended by the excessive protruding stroke or excessive retracting stroke amount by the transmission member, thereby discharging control oil;
a control oil supply system that supplies control oil discharged from each of the pair of control cylinder units to the damping valve unit,
The damping valve unit is provided with a spring seat that is located on the opposite side of the valve body across the spring member, and is moved to compress the spring member with control oil supplied from the control oil supply system, thereby increasing the spring force of the spring member according to the amount of excess protrusion stroke and the amount of excess retraction stroke, and a return means that returns control oil to each of the control cylinder units to return each of the control piston rods to their initial positions. The oil damper system described in claim 1, characterized in that the return means is set to a spring force that presses the spring seat so that the spring member causes the control oil to flow out into the control oil supply system. The oil damper system described in claim 1 or 2, characterized in that the return means is a shim provided between the spring seat and the valve body, overlapping the spring member, and causing the spring member to press the spring seat so as to cause the control oil to flow into the control oil supply system. The oil damper system according to any one of claims 1 to 3, characterized in that the return means is a return spring formed with a spring constant smaller than the spring constant of the spring member, provided in parallel with the spring member between the spring seat and the valve body, and pressing the spring seat from the valve body side so as to cause the control oil to flow out into the control oil supply system. An oil damper system as described in any one of claims 1 to 4, characterized in that the return means returns control oil to each of the control cylinder units when the flow of hydraulic oil that moves the valve body ceases.