JP4456779B2 - Hydraulic shock absorber - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a hydraulic shock absorber used, for example, as a seismic isolation damper for a building.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a hydraulic shock absorber disclosed in, for example, Japanese Patent Application Laid-Open No. 9-42347 is provided with a reservoir chamber having a gas chamber in a part thereof, and a disk-shaped oil level fluctuation suppressing member that suppresses oil level fluctuation in the reservoir chamber. Is attached.
[0003]
[Problems to be solved by the invention]
However, in such a conventional hydraulic shock absorber, since the disk-shaped oil level fluctuation suppressing member is arranged so as to be orthogonal to the cylinder, the hydraulic shock absorber is used so that the cylinder extends substantially in the horizontal direction. When this is done, there is a problem that the oil level fluctuation suppressing effect in the reservoir chamber is hardly obtained.
[0004]
In addition, since the oil level fluctuation suppressing member is fixedly attached to a cylinder or the like, processing and assembly related to the oil level fluctuation suppressing member become complicated, resulting in an increase in product cost.
[0005]
The present invention has been made in view of the above problems, and an object of the present invention is to enhance the effect of suppressing fluctuations in the oil level in a hydraulic shock absorber extending in a substantially horizontal direction.
[0006]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided an inner cylinder for slidably mounting a piston, an outer cylinder defining a reservoir chamber having a gas chamber partially outside the inner cylinder, and operating oil in the reservoir chamber in the inner cylinder. The present invention is applied to a hydraulic shock absorber that includes a suction port that leads to the inner cylinder and a discharge pipe that guides hydraulic oil in the inner cylinder to the reservoir chamber, and is arranged so that the center line of the inner cylinder extends in a substantially horizontal direction.
[0007]
The reservoir chamber is provided with a cylindrical oil level fluctuation suppressing pipe surrounding the inner cylinder, the suction port and the discharge pipe.
[0008]
According to a second invention, in the first invention, the oil level fluctuation suppressing pipe is placed at the bottom of the outer cylinder.
[0009]
The third invention is characterized in that, in the first or second invention, a plurality of holes penetrating the oil level fluctuation suppressing pipe are formed, and each hole is arranged in the vicinity of the suction port.
[0010]
Operation and effect of the invention
According to the first aspect of the present invention, the oil level fluctuation suppressing pipe surrounding the discharge pipe and the suction port is provided, so that the hydraulic oil ejected to the reservoir chamber through the discharge pipe flows into the oil level fluctuation suppressing pipe, The inside of the surface fluctuation suppressing pipe is filled with hydraulic oil, and gas is prevented from being sucked from the suction port, and a predetermined attenuation waveform characteristic is maintained.
[0011]
According to the second invention, since the oil level fluctuation suppressing pipe is placed at the bottom of the outer cylinder, there is no need to provide means for fixing the oil level fluctuation suppressing pipe, sealing means, etc. The complexity of processing and assembly is avoided, and the cost of the product is reduced.
[0012]
According to the third aspect of the invention, even when the hydraulic fluid inside the oil level fluctuation suppression pipe is suddenly operated so that all of the hydraulic oil inside the oil level fluctuation suppression pipe is sucked from the suction port, the hydraulic oil in the reservoir chamber is removed from the plurality of holes formed in the oil level fluctuation suppression pipe Since the gas flows in toward the suction port, the gas is prevented from being sucked from the suction port, and a predetermined attenuation waveform characteristic is maintained.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0014]
FIG. 1 shows a hydraulic shock absorber 1 used as a seismic isolation damper for a building. The hydraulic shock absorber 1 is arranged such that the center line O of the piston rod 2, the inner cylinder 3, the outer cylinder 4 and the like extends substantially horizontally, and the tip (not shown) of the piston rod 2 is on the foundation (ground) side. The base end 4a of the outer cylinder 4 is connected to the building, and the base side vibrates in the horizontal direction when an earthquake occurs, thereby expanding and contracting to generate a damping force.
[0015]
As shown in FIG. 1A, the inner cylinder 3 is fixed inside the outer cylinder 4 via a bottom plate 12. The piston rod 2 is slidably supported by the bearing portion 11 of the outer cylinder 4 in the middle. A piston 5 is connected to the base end portion of the piston rod 2, and the piston 5 is slidably accommodated inside the inner cylinder 3.
[0016]
The inside of the inner cylinder 3 is partitioned by a piston 5 into a rod side oil chamber 7 and an end side oil chamber 8. A reservoir chamber 9 having a gas chamber in part is defined between the inner cylinder 3 and the outer cylinder 4.
[0017]
As shown in FIGS. 3A and 3B, the gas and the hydraulic oil are divided into upper and lower parts inside the reservoir chamber 9, and an oil reservoir area 9A in which the hydraulic oil is accumulated and a gas reservoir area in which the gas is accumulated ( Gas chamber) 9B is created.
[0018]
The bearing unit 11 is provided with a damping valve 20. The hydraulic oil flowing from the rod side oil chamber 7 to the reservoir chamber 9 passes through the damping valve 20 in the extension side stroke and the pressure side stroke in which the hydraulic shock absorber 1 is expanded and contracted.
[0019]
In order to equalize the flow rate of hydraulic oil passing through the damping valve 20 in the extension side stroke and the pressure side stroke, the outer diameter of the piston rod 2 and the inner diameter of the inner cylinder 3 have a relationship of 1: √2.
[0020]
The piston 5 is provided with a check valve 21. The hydraulic oil flowing from the end side oil chamber 8 to the rod side oil chamber 7 in the pressure side stroke in which the hydraulic shock absorber 1 contracts passes through the check valve 21.
[0021]
A check valve 22 is provided on the bottom plate 12 on the piston side. The hydraulic fluid that flows from the reservoir chamber 9 to the end side oil chamber 8 in the expansion side stroke in which the hydraulic shock absorber 1 extends passes through the check valve 22.
[0022]
A plurality of ports 13 penetrating the bottom plate 12 are formed, and each port 13 is opened and closed by a check valve 22. A suction port 14 that connects the reservoir chamber 9 and each port 13 is formed between the bottom plate 12 and the outer cylinder 4, and the hydraulic oil stored in the reservoir chamber 9 passes through the suction port 14 and each port 13 in this order to reach the end side It flows into the oil chamber 8.
[0023]
The suction port 14 opens at the lowermost portion of the bottom plate 12, and the opening end thereof faces the hydraulic oil stored in the reservoir chamber 9.
[0024]
A discharge pipe 19 connected to the outlet 15 of the damping valve 20 is attached to the bearing portion 11. The discharge pipe 19 extends substantially parallel to the inner cylinder 3 and is disposed below the inner cylinder 3. The opening end 19 a of the discharge pipe 19 is directed to the opening end of the suction port 14, and hydraulic oil that has flowed out of the discharge pipe 19 into the reservoir chamber 9 flows toward the suction port 14.
[0025]
The reservoir chamber 9 is provided with a cylindrical oil level fluctuation suppressing pipe 30 surrounding the inner cylinder 3, the suction port 14 and the discharge pipe 19, and the oil level fluctuation suppressing pipe 30 causes the oil level fluctuation of the hydraulic oil in the reservoir chamber 9. Be suppressed.
[0026]
As shown in FIG. 1B, the oil level fluctuation suppressing pipe 30 is placed at the bottom of the outer cylinder 4 and does not have a fixing means or a sealing means for the bottom plate 12 or the like. The inner cylinder 3, the outer cylinder 4, and the oil level fluctuation suppressing pipe 30 are each formed in a right cylindrical shape. The oil level fluctuation suppression pipe 30 is placed at the bottom of the outer cylinder 4 by gravity, so that the centers of the oil level fluctuation suppression pipe 30, the inner cylinder 3, the outer cylinder 4, and the discharge pipe 19 are aligned on the vertical line C.
[0027]
Gaps 16 and 17 are provided between both ends 30a and 30b of the oil level fluctuation suppression pipe 30 and the outer cylinder 4, respectively. A gap 18 is provided between the ceiling portion of the oil level fluctuation suppressing pipe 30 and the upper portion of the inner cylinder 3. The hydraulic oil in the reservoir chamber 9 enters and exits the oil level fluctuation suppressing pipe 30 through the gaps 16, 17 and 18.
[0028]
As shown in FIG. 2, the oil level fluctuation suppressing pipe 30 is formed with a plurality of holes 31 penetrating therethrough. Each hole 31 is formed at the end side end portion of the oil level fluctuation suppressing pipe 30 so as to be positioned in the vicinity of the suction port 14. As a result, the hydraulic oil flowing into the oil level fluctuation suppression pipe 30 through each hole 31 is directed toward the suction port 14.
[0029]
Next, the operation of the embodiment of the present invention configured as described above will be described.
[0030]
In the pressure side stroke of the hydraulic shock absorber 1, the end-side check valve 22 is closed, while the piston-side check valve 21 is opened, and as shown by an arrow in FIG. In addition to flowing from the side oil chamber 8 through the check valve 21 into the rod side oil chamber 7, hydraulic oil corresponding to the intrusion volume of the piston rod 2 flows from the rod side oil chamber 7 through the damping valve 20 into the reservoir chamber 9. A predetermined damping force is generated.
[0031]
In the extension stroke of the hydraulic shock absorber 1, the check valve 20 on the piston side is closed, while the check valve 22 on the end side is opened, and as shown by an arrow in FIG. While flowing from the reservoir chamber 9 through the check valve 22 into the end side oil chamber 8 and from the rod side oil chamber 7 through the damping valve 20 into the reservoir chamber 9, a damping force similar to that on the pressure side is generated.
[0032]
Thus, the hydraulic oil in the reservoir chamber 9 is sucked into the suction port 14 only in the extension side stroke. However, when the piston speed increases, the oil level of the reservoir chamber 9 varies.
[0033]
Here, when the oil level fluctuation suppressing pipe 30 is not provided in the reservoir chamber 9, gas is sucked from the suction port 14 due to oil level fluctuation, and a predetermined attenuation waveform characteristic cannot be obtained.
[0034]
In contrast, according to the present invention, the oil level fluctuation suppression pipe 30 surrounding the discharge pipe 19 and the suction port 14 is provided, so that the hydraulic oil jetted into the reservoir chamber 9 through the discharge pipe 19 is oil level fluctuation suppression pipe 30. Since the state in which hydraulic oil is filled inside the oil level fluctuation suppression pipe 30 is maintained, the intake of gas from the oil level fluctuation suppression pipe 30 is prevented, and a predetermined attenuation waveform characteristic is maintained. Is done.
[0035]
Even when the hydraulic fluid inside the oil level fluctuation suppression pipe 30 is suddenly operated so that all of the hydraulic oil inside the oil level fluctuation suppression pipe 30 is sucked from the suction port 14, the hydraulic oil in the reservoir chamber 9 flows from the plurality of holes 31 formed in the oil level fluctuation suppression pipe 30. Since the oil quickly flows into the fluctuation suppression pipe 30, the amount of hydraulic oil in the oil level fluctuation suppression pipe 30 is maintained.
[0036]
At this time, since the hydraulic oil flowing into the oil level fluctuation suppression pipe 30 through each hole 31 flows toward the suction port 14, the suction port 14 is prevented from entering the gas, and a predetermined attenuation is achieved. Waveform characteristics are maintained.
[0037]
Since the oil level fluctuation suppressing pipe 30 is placed at the bottom of the outer cylinder 4, there is no need to provide a fixing means or a sealing means for the bottom plate 12 or the like, and the structure can be simplified.
[0038]
Moreover, it is good also as a structure which fixes and attaches the oil level fluctuation suppression pipe 30 to the baseplate 12 grade | etc., As needed. In this case, it is possible to prevent vibration and noise from being generated during transportation.
[0039]
The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a hydraulic shock absorber according to an embodiment of the present invention.
FIG. 2 is a perspective view of an oil level fluctuation suppressing pipe.
FIG. 3 is a cross-sectional view for explaining the operation of the hydraulic shock absorber.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hydraulic buffer 2 Piston rod 3 Inner cylinder 4 Outer cylinder 5 Piston 7 Rod side oil chamber 8 End side oil chamber 9 Reservoir chamber 14 Suction port 19 Discharge pipe 20 Damping valve 21 Check valve 22 Check valve 30 Oil level fluctuation suppression pipe 31 hole

Claims (3)

An inner cylinder that slidably houses a piston;
An outer cylinder defining a reservoir chamber partially having a gas chamber outside the inner cylinder;
A suction port for guiding the hydraulic oil in the reservoir chamber into the inner cylinder;
A discharge pipe for guiding the hydraulic oil in the inner cylinder to the reservoir chamber,
In the hydraulic shock absorber arranged so that the center line of the inner cylinder extends in a substantially horizontal direction,
A hydraulic shock absorber characterized in that a cylindrical oil level fluctuation suppressing pipe surrounding an inner cylinder, a suction port and a discharge pipe is provided in the reservoir chamber. The hydraulic shock absorber according to claim 1, wherein the oil level fluctuation suppressing pipe is placed at a bottom portion of the outer cylinder. Forming a plurality of holes penetrating the oil level fluctuation suppressing pipe,
The hydraulic shock absorber according to claim 1 or 2, wherein each hole is arranged in the vicinity of the suction port.

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