JP6906408B2 - Piston damper and isolator - Google Patents

Description

The present invention relates to a piston type damper that attenuates vibration and an isolator using the piston type damper.

In a structure that performs highly accurate positioning or directional control, it is required to reduce minute vibrations generated by a driving device in order to increase the control resolution. Patent Documents 1 to 3 describe a vibration insulation device that attenuates vibration in a wide band.

Patent Document 1 describes a welded bellows type damper that uses oil as a working fluid and expands and contracts according to the flow of oil.
The bellows described in Patent Document 1 is made of metal and has environmental resistance. The bellows has a structure in which a thin plate is formed or a structure in which a thin plate is welded because it is necessary to ensure flexible elasticity within a specified dimension in the axial direction. From the viewpoint of extending the service life, it is recommended that the bellows have a structure in which a thin plate is welded so that stress is not easily concentrated.

Patent Document 2 describes a device having a piston type damper using oil as a working fluid. Although the piston type damper is effective for large-amplitude vibration, there is a problem that it is difficult to obtain the effect of reducing minute vibration because of the large friction. Therefore, in Patent Document 2, the reduction of minute vibration is reduced by using a viscoelastic body in addition to the piston type damper.

Patent Document 3 describes a coupling method in which minute gaps are not generated in the fastening member of the damper in order to insulate minute vibrations.

JP-A-2017-067272 Japanese Unexamined Patent Publication No. 11-141174 Japanese Unexamined Patent Publication No. 2005-126497

As described in Patent Document 1, the bellows has elasticity in the axial direction and also has volume elasticity due to deformation of the bellows plate. Volumetric elasticity is elasticity in the direction orthogonal to the axis on which the load is input. When the bellows receives a compressive force due to vibration, the oil flow rate that flows from the bellows to the orifice and exhibits damping is the amount obtained by excluding the volume integral expanded by volume elasticity from the volume changed by the axial expansion and contraction of the bellows. Become.
The bellows type damper described in Patent Document 1 has a problem that the volume expanded by the volume elasticity at the time of minute vibration becomes significant and the damping performance is deteriorated.

On the other hand, since the piston type damper described in Patent Document 2 has almost no volume elasticity, this deterioration does not occur even if it is a minute vibration. However, there is a problem that the above-mentioned friction is large.

An object of the present invention is to construct a damper capable of damping even a minute vibration.

The piston type damper according to the present invention is
A piston in which rods are provided on both sides in the axial direction and a plurality of grooves extending in the axial direction from one surface in the axial direction to the other surface are formed.
Through holes provided on both sides through which the rods penetrate are formed, and the cylinder includes the piston, and includes a cylinder in which a fluid is filled in a gap between the inner wall and the piston.

In the present invention, since the piston is formed with a plurality of grooves extending in the axial direction, the piston is prevented from coming into contact with the tilted cylinder. As a result, frictional resistance can be suppressed, and even minute vibrations can be damped.

FIG. 3 is a cross-sectional view of the piston type damper 1 according to the first embodiment. The figure which shows the state which cut and expanded the inner cylinder 31 which concerns on Embodiment 1. FIG. Explanatory drawing of groove 23 which concerns on Embodiment 1. FIG.

Embodiment 1.
*** Explanation of configuration ***
The configuration of the piston type damper 1 according to the first embodiment will be described with reference to FIGS. 1 to 3.

As shown in FIG. 1, the piston type damper 1 includes a piston 2 and a cylinder 3. The piston 2 is provided with rods 4 on both sides in the axial direction. The cylinder 3 is formed with through holes 5 through which each of the rods 4 provided on both sides penetrates, and includes the piston 2. The cylinder 3 is filled with a highly viscous fluid such as oil in the gap between the inner wall and the piston 2. Here, this fluid is hereinafter referred to as oil.
The cylinder 3 has an inner cylinder 31 that includes the piston 2 and an outer cylinder 32 that includes the inner cylinder 31 with a gap. The inner cylinder 31 is formed with a hole 51 which is a through hole 5, and the outer cylinder 32 is formed with a hole 52 which is a through hole 5. When the rod 4 is penetrated through the hole 51, a gap is formed between the open end of the hole 51 in the inner cylinder 31 and the rod 4. Further, when the rod 4 is penetrated through the hole 52, a gap is formed between the open end of the hole 52 in the outer cylinder 32 and the rod 4.
The oil filled in the cylinder 3 can flow through the gap between the inner cylinder 31 and the piston 2 and the gap between the outer cylinder 32 and the inner cylinder 31 through the hole 51 formed in the inner cylinder 31. That is, the oil can flow through the gap between the open end of the hole 51 and the rod 4 in the inner cylinder 31.

As shown in FIGS. 2 and 3, the piston 2 is formed with a plurality of grooves 23 extending in the axial direction from one surface 21 in the axial direction to the other surface 22. As shown in FIG. 3, each of the plurality of grooves 23 becomes deeper toward the end in the axial direction and shallower toward the center in the axial direction. Each of the plurality of grooves 23 has, for example, a wedge-shaped, semi-circular, semi-elliptical, or U-shaped cross section in the direction perpendicular to the axial direction.

As shown in FIG. 1, the piston type damper 1 includes a lid 6 and a bellows 7 corresponding to each of the rods 4 provided on both sides. The lid 6 is provided on the outside of the cylinder 3 and is connected to the end of the corresponding rod 4. The bellows 7 surrounds the corresponding rod 4 and connects the lid 6 connected to the end of the corresponding rod 4 and the outer cylinder 32. One end of the bellows 7 is connected to the surface of the lid 6 on the outer cylinder 32 side, and the other end is connected to the surface of the outer cylinder 32 on the lid 6 side. The bellows 7 corresponding to each of the rods 4 provided on both sides have the same dimensions and rigidity.
The gap between the bellows 7 and the rod 4 is filled with oil. The oil can flow through the gap between the bellows 7 and the rod 4 and the gap between the outer cylinder 32 and the inner cylinder 31 through the hole 52 formed in the outer cylinder 32. That is, the oil can flow through the gap between the open end of the hole 52 in the outer cylinder 32 and the rod 4.

As shown in FIG. 1, the piston type damper 1 includes a fixing flange 8 for fixing the cylinder 3.

The piston type damper 1 can form an isolator that insulates vibration. When the isolator is configured by using the piston type damper 1, the piston type damper 1 and the primary spring are installed in parallel. The isolator insulates vibrations at frequencies higher than the resonant frequency of the primary spring.
It is also possible to make the bellows 7 included in the piston type damper 1 function as a primary spring of the isolator by giving an appropriate rigidity in the expansion / contraction direction. That is, by giving the bellows 7 appropriate rigidity in the expansion / contraction direction, the isolator can be configured without using a separate primary spring.

*** Explanation of operation ***
The operation of the piston type damper 1 according to the first embodiment will be described with reference to FIG.
When vibration is transmitted to the rods 4 on both sides in the axial direction, the movement of the piston 2 pressurizes the space on one side of the piston 2 inside the inner cylinder 31 and reduces the space on the other side. Then, the oil in the space on the pressurized side flows through the gap between the open end of the hole 51 and the rod 4 in the inner cylinder 31. This damps the vibration.
The gap between the open end of the hole 51 and the rod 4 is set to the size and shape of the gap that causes vibration damping due to the kinematic viscosity resistance of the oil.

If the shaft of the piston 2 has a slight angle with respect to the central shaft of the cylinder 3, that is, if the shaft of the piston 2 is tilted, it will come into contact with the inner cylinder 31 when the piston 2 moves. That is, the piston 2 hits the inner cylinder 31 on one side. This causes frictional resistance.
However, in the piston type damper 1, a plurality of grooves 23 are formed in the piston 2. Due to the plurality of grooves 23, when the shaft of the piston 2 is tilted, the oil exerts a force for restoring the tilt of the shaft of the piston 2. As a result, the shaft of the piston 2 is prevented from tilting, and the piston 2 is prevented from hitting the inner cylinder 31 on one side. As a result, frictional resistance is reduced.
Specifically, when the piston 2 moves, if the piston 2 is likely to hit one side, the gap between the groove 23 formed in the portion likely to hit one side and the inner wall of the inner cylinder 31 is narrowed. Therefore, the pressure is locally increased. On the other hand, the gap between the groove 23 formed in the axially symmetrical portion with respect to the portion likely to hit one side and the inner wall of the inner cylinder 31 becomes wide. Therefore, the pressure is locally reduced. Due to this pressure difference, a moment force is generated on the piston 2 in a direction for avoiding one-sided contact. In particular, each of the plurality of grooves 23 becomes deeper toward the end in the axial direction and shallower toward the center in the axial direction. Therefore, a moment force in a direction for avoiding one-sided contact is likely to be generated.
Here, each of the plurality of grooves 23 is formed from the surface 21 to the surface 22 in the axial direction, and there is no portion where the depth becomes zero. Therefore, even when the piston 2 starts to move from the state where the piston 2 is not moving and the piston 2 is in contact with the inner wall of the inner cylinder 31, the flow rate of the oil in each of the plurality of grooves 23 is zero. It does not become. Therefore, immediately after the piston 2 starts moving, a moment force in a direction for avoiding one-sided contact is generated. As a result, the piston 2 does not hit one side.

When vibration is transmitted to the rods 4 on both sides in the axial direction and the piston 2 moves, the oil in the space on the pressurized side creates a gap between the open end of the hole 51 in the inner cylinder 31 and the rod 4. It flows. The inner cylinder 31 is included in the outer cylinder 32. Therefore, the oil that has flowed through the gap between the open end of the hole 51 and the rod 4 in the inner cylinder 31 flows into the space between the outer cylinder 32 and the inner cylinder 31.
The piston 2 moves, and the space on the decompressed side has a negative pressure. Therefore, the oil in the space between the outer cylinder 32 and the inner cylinder 31 flows into the space on the decompressed side.
Here, the outer cylinder 32 includes the inner cylinder 31 with a gap. This gap has a cross-sectional area that allows the oil to easily flow. Therefore, the oil flow velocity associated with the movement of the piston 2 is almost zero. Therefore, the internal pressure of the space between the outer cylinder 32 and the inner cylinder 31 becomes substantially constant regardless of the internal pressure of the inner cylinder 31 due to vibration.

It is conceivable to use the piston type damper 1 for products used in space such as artificial satellites. In this case, the outside pressure is 1 atm on the ground, but the outside pressure becomes almost zero on the orbit. Therefore, the relative pressure of the oil inside the piston type damper 1 is zero on the ground, but becomes a positive pressure of +1 atm on the orbit. In addition, it is exposed to drastic changes in the temperature environment, and the volume increases or decreases due to changes in the temperature of the oil.
In the piston type damper 1, fluctuations in pressure inside the inner cylinder 31 can be absorbed by the space between the outer cylinder 32 and the inner cylinder 31. Therefore, even when the piston type damper 1 is used as a product to be used in space, it is possible to reduce the change in damping performance due to the fluctuation of the pressure inside the inner cylinder 31.

Bellows 7 are arranged to face each other on both outer sides of the cylinder 3 in the axial direction. The bellows 7 relieves pressure by volumetric elasticity. The total length of the two bellows 7 arranged on both outer sides is fixed by the rod 4. Since the total length of the two bellows 7 is fixed, when one bellows 7 is compressed, the other bellows 7 expands by the amount of compression. Further, the oil can flow in the space between the bellows 7 and the outer cylinder 32 and the space between the outer cylinder 32 and the inner cylinder 31.
Therefore, the two bellows 7 do not affect the flow rate of the oil excited by the piston 2. On the other hand, the two bellows 7 can absorb a static change in pressure and prevent a decrease in damping performance.

*** Effect of Embodiment 1 ***
As described above, in the piston type damper 1 according to the first embodiment, the gap between the inner cylinder 31 and the piston 2 is filled with oil, and the piston 2 is formed with a plurality of grooves 23 which are shallower toward the center portion. There is. As a result, a moment force is generated in a direction for avoiding one-sided contact, and one-sided contact is prevented. As a result, frictional resistance is reduced.

Further, in the piston type damper 1, the outer cylinder 32 includes the inner cylinder 31 with a gap. As a result, it is possible to prevent a decrease in damping performance based on factors such as a change in the internal pressure of the inner cylinder 31 and a change in temperature.

Further, in the piston type damper 1, bellows 7 are arranged on both outer sides of the cylinder 3 in the axial direction. As a result, it is possible to absorb the change in pressure and prevent the deterioration of the damping performance.
In addition, when the bellows 7 is used, there is a problem that the volume expanded by the volume elasticity becomes significant and the damping performance is deteriorated. This problem is solved by allowing oil to flow in the space between the bellows 7 and the outer cylinder 32 and the space between the outer cylinder 32 and the inner cylinder 31.

That is, the conventional piston type damper does not cause a decrease in the flow rate due to volume elasticity, but there is a problem 1 that the frictional resistance is large. The conventional bellows type damper does not cause a frictional resistance, but the flow rate is reduced due to volume elasticity. There was a problem 2 that the occurrence of. Further, the conventional oil type damper for space use has a problem 3 that it is necessary to have a function of alleviating pressure fluctuations due to the environment and to stabilize the damping performance.
On the other hand, the piston type damper 1 according to the first embodiment solves the above problems 1 and 2 by having a thin groove 23 around the side surface of the piston 2.
Further, the piston type damper 1 according to the first embodiment solves the above-mentioned problem 3 by providing two bellows mechanisms that do not change in total length and operate in opposition to each other. That is, the bellows mechanism provided in the piston type damper 1 according to the first embodiment relaxes the pressure by the volume elasticity of the bellows 7, and two pairs of bellows are arranged as a means for solving the problem 3 that occurs when the bellows mechanism is used. It has the function of not causing fluctuations in the internal pressure because the oil in the part can flow freely.

That is, in order to solve the problems 1 and 2, the piston type damper 1 according to the first embodiment is
A piston in which rods are provided on both sides in the axial direction and a plurality of grooves extending from one surface in the axial direction to the other surface are formed.
Through holes provided on both sides through which the rods penetrate are formed, and the cylinder includes the piston, and includes a cylinder in which a fluid is filled in a gap between the inner wall and the piston.

Further, in order to solve the above-mentioned problem 3, the piston type damper 1 according to the first embodiment is
A piston with rods on both sides in the axial direction,
Through holes provided on both sides through which the rods penetrate are formed, and a cylinder containing the piston and a cylinder.
A lid provided on the outside of the cylinder corresponding to each of the rods provided on both sides and connected to the end of the corresponding rod.
It is provided corresponding to each of the rods provided on both sides, and includes a bellows that surrounds the corresponding rods and connects the lid and the cylinder to which the ends of the corresponding rods are connected.

Further, in order to solve the above-mentioned problem 3, the piston type damper 1 according to the first embodiment is
For each of the rods provided on both sides, the total volume of the space formed by the rod, the bellows, the lid, and the outer cylinder is constant.

Further, in order to solve the above-mentioned problem 3, the piston type damper 1 according to the first embodiment is
The fluid is filled so as to be able to flow through the gap between the outer cylinder and the inner cylinder and the space formed by the rod, the bellows, the lid, and the outer cylinder.

1 Piston type damper, 2 pistons, 21 and 22 surfaces, 23 grooves, 3 cylinders, 31 inner cylinders, 32 outer cylinders, 4 rods, 5 through holes, 51, 52 holes, 6 lids, 7 bellows, 8 fixed flanges.

Claims (7)

Rods were provided on both sides in the axial direction, and a plurality of grooves extending from one surface in the axial direction to the other surface were formed, and a plurality of grooves became shallower as they became closer to the central portion in the axial direction. With the piston
A piston-type damper having through holes provided on both sides through which the rods penetrate, and a cylinder containing the piston, the cylinder having a fluid filled in a gap between an inner wall and the piston. A piston in which rods are provided on both sides in the axial direction and a plurality of grooves extending from one surface in the axial direction to the other surface are formed.
A cylinder provided with a through hole through which each of the rods provided on both sides is formed and contains the piston, and includes a cylinder in which a fluid is filled in a gap between an inner wall and the piston .
The cylinder
An inner cylinder containing the piston and
With an outer cylinder that contains the inner cylinder with a gap
Piston damper having. The piston type damper according to claim 2, wherein the fluid can flow through a gap between the inner cylinder and the piston and a gap between the outer cylinder and the inner cylinder. A piston in which rods are provided on both sides in the axial direction and a plurality of grooves extending from one surface in the axial direction to the other surface are formed.
A cylinder in which a through hole through which each of the rods provided on both sides penetrates is formed and includes the piston, and a cylinder in which a fluid is filled in a gap between an inner wall and the piston .
A lid provided on the outside of the cylinder corresponding to each of the rods provided on both sides and connected to the end of the corresponding rod.
A bellows and a bellows, which are provided corresponding to each of the rods provided on both sides, surround the corresponding rods, and connect the lid and the cylinder to which the ends of the corresponding rods are connected. Piston type damper equipped with. The cylinder
An inner cylinder containing the piston and
With an outer cylinder that contains the inner cylinder with a gap
Have,
The piston type damper according to claim 4, wherein the total volume of the space formed by being surrounded by the rod, the bellows, the lid, and the outer cylinder for each of the rods provided on both sides is constant. The piston according to claim 5, wherein the fluid can flow through a gap between the outer cylinder and the inner cylinder and a space formed by being surrounded by the rod, the bellows, the lid, and the outer cylinder. Ceremony damper. The isolator having the piston type damper according to any one of claims 1 to 6.

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