JPS5997337A - Hydraulic buffer - Google Patents

Abstract

PURPOSE:To effectively decrease the amplitude in prescribed exciting frequency regions, by fitting two rotors on a piston rod and providing the rotors with horizontally-penetrating oil passages and vertically-penetrating rotatory force causing fluid passages to reduce a damping force or not to cause it. CONSTITUTION:A rotor 13 having a rotatory force causing groove 23, a rotor 14 provided with a rotary spring 16 and with no rotatory force causing groove and a rotary spring 17 constitute rotational vibration systems having particular frequency characteristics. One of oil passages 18a, 18b is connected to or disconnected from the end of the oil passage 20 of a piston rod 2 depending on the vibration. For the exciting vibration systems of 2 in degree of freedom, the moment of inertia of the rotors 13, 14 and the constants k1, k2 of the springs 16, 17 are set at optional values to provide the rotational angles of the rotors with characteristics. The rotational vibration amplitude of the rotors 13, 14 is provided with a frequency dependency so as to reduce a damping force in such regions of angular frequency as omegacr1<omega<=omegacr2 and omegacr3<omega<=omegam. The vibration amplitude of a vehicle body of m in mass is thus effectively restricted as in other regions.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic shock absorber that is attached to a vehicle and absorbs vehicle body vibration.

Periodic vibrations are transmitted to the vehicle when it is driven on the road, so a damper is installed in parallel with the spring between the body frame and the suspension, and by selecting these constants and coefficients, It is designed to improve ride comfort.

This vibration damping operation will now be explained with reference to the two-degree-of-freedom vibration system shown in Fig. 1 and the amplitude characteristics shown in Fig. 2.

In Figure 1, ml, m:l are the unsprung and unsprung masses, k, , k are the unsprung and unsprung spring constants, C2 is the damping coefficient of the sprung mass, and DCo is the excitation displacement that is the road surface displacement. , Zl is the displacement from the unsprung equilibrium position, and Zl is the displacement from the unsprung equilibrium position 1αos (L, l is $6, displacement of Jt2, δu is the phase displacement of x2, ω is the angular frequency, t If time is the excitation displacement -To is X.=
αoS .

Furthermore, the amplitude α of x2 has a characteristic as shown in Figure +2, and when there is no attenuator, that is, when the damping coefficient C is α−O, the angular frequency ω becomes 0〈ω and ωCγ/ ,ω0γko〈
It has two resonance points that rise sharply in the region of ω and ωcrJ, and exhibits resonance characteristics as shown by the curve P/, with a damping coefficient c 7
% c. In the case of , the angular frequency ω has two resonance points that rise gently in the same region as above, and exhibits resonance characteristics as shown by curve 9.

According to this, if the excitation angular frequency (marginal angular frequency) at which the dihedral lines p, , p intersect is ωCr/ mωCγko, ωcr3, then the angular frequency ω is θ<ω×ωcr/ and ωcr, ), 〈ω〉ωtyr3, the vibration of the mass m2 and the amplitude α can be suppressed smaller with the damper than without it, whereas the above angular frequency ω is ωCγ/〈ω〉 ω. In the region where γyu and ω〉ωcr, 1, on the other hand, the amplitude CL is smaller when there is no attenuator than when there is an attenuator.
2 is small and the presence of the damper actually impairs the vibration prevention effect. In addition, the above-mentioned limit angular frequency ωc
r/sωcr2aωcr3 is a constant determined by masses m1, m2, a spring constant, and 2.

From the above, in order to suppress the vibration transmitted to the mass 7rL2, that is, the vibration of the vehicle body, ω is 0. γノ、ω0γゆ〈ωくω. In the region of γ3, the attenuator is applied.
In the region of ωcri<ω×ωCγ2jω>ωcr3, it is preferable not to operate the attenuator.

However, since the damping force of a conventional hydraulic shock absorber is uniquely determined only by the excitation speed, regardless of the angular frequency, the above-mentioned ω. γ/kuωkuω. In the regions of γ, ω>ω, and γ3, the damping coefficient 02 had the above-mentioned adverse effect on the vibration system.

This invention was made by focusing on this problem, and by reducing or preventing the damping force from being generated in a predetermined excitation frequency range that can be set arbitrarily, the vibration level in the predetermined excitation frequency range can be reduced. The purpose is to effectively reduce the

In order to achieve this objective, the present invention includes two ring-shaped rotors that are rotatably inserted into the piston rod, a rotating spring of rice 2 that is linked between these rotors, and one of these rotors and the piston. The first link is connected to the rod side.
a rotating spring, an oil passage passing through the inner and outer peripheries of either one of the rotors and having an open end communicating with one of the oil chambers, and a rotational force passing through the top and bottom of either of the rotors; two vibration systems whose excitation source is the rotational force of the rotor generated when oil passes through this rotational force generation flow path, and a predetermined excitation of both vibration systems. In the frequency range, the structure is such that oil can flow between the two oil chambers via the oil passage provided in the center of the piston rod and the oil passage provided in the rotor.

Embodiments of the present invention will be described below with reference to the drawings.

Figures 3, 4 and 5 are longitudinal and cross-sectional views of the hydraulic shock absorber of the present invention. In the same figure,
(1) is a cylinder, (2) is a piston rod inserted into one sealed end of this cylinder (1) so as to be freely removable, (3)
is attached to the narrow diameter part (2α) at the end of the piston rod (2) and divides the inside of the cylinder (1) into two oil chambers A and H, and (4) is fitted to the end of the piston rod (2). The combined valve stopper (5) is a valve disc interposed between this valve stopper (4) and the piston (3), and these are connected to the piston rod (2) as shown.
The narrow diameter part of the end is successively inserted, and the Nara l' (6) K
Fixed.

In addition, the piston (3) has an oil hole (7) penetrating vertically.
) and a recess (8) covered by a leaf valve (9) and a valve disc (5), which will be described later, are provided in the upper part, and a recess (8) is provided in the upper part, which is covered by a leaf valve (9) and a valve disc (5), which will be described later. An oil hole aO) is provided which is opened and closed by the leaf valve (9) installed. Furthermore, a valve disk (5) is connected between the valve disk (5) and the valve stopper (4) via a leaf valve (9) and the piston (
3) Valve spring (11) 5 that presses against the top surface:
It has been intervened. (12) is a notch that penetrates inside and outside of the valve stopper (4). In addition, (3a) is a piston (
This is a seal ring inserted into the outer peripheral notch of 3).

(131f14) are two rotors that are rotatably fitted into the large diameter portion of the end of the piston rod (2), and their axial movement is restricted by three upper and lower snap rings. One end of each rotation spring (17) of the coiled fang 2 is locked to the upper surface of the rotor a3) and the lower surface of the mouth (141), and the lower surface of the rotor (13) and the piston rod f21 side One end of each of 1,100 coiled rotation springs (1G) is locked to the upper surface of the barrel valve stopper (4).

Furthermore, within the thickness of the rotor 03), two oil passages (18a) (18b) are provided in a radial manner passing through the inner and outer circumferences of the rotor 03), and these oil passages (18α) (1sA) A notch Og) communicating with the oil chamber A is formed on the outer periphery of the rotor (131).The piston rod (2)
is penetrated through the center of the oil chamber B, and one end thereof is opened to the oil chamber B,
The other end is an oil passage that opens on the outer peripheral surface of the piston rod (2), and the oil passage (
18α) or (18b) are selectively communicated with this oil road price. 011 is a fan-shaped notch formed within the thickness of the rotor (131), and the pin-shaped stopper (221) fixed in the piston rod (2) is protruded from the east side of the notch, which indicates the amount of rotation of the rotor 113. Regulate it. (
Reference numeral 23) denotes a rotational force generating groove formed on the outer periphery of the rotor 03), which is inclined in the axial direction, and when oil flows therethrough, the rotor a is urged to rotate. In order to obtain the same effect as this rotation generation groove (231), the rotation force generation groove (23) may be replaced with a rotation force generation hole that vertically penetrates the rotor α, or a plurality of rotation force generation holes protruding from the outer circumference of the rotor 03) may be used. The space between the vanes can be used as a flow path for generating rotational force.

On the other hand, the rotor (141) has a smaller diameter than the rotor (L31), allowing oil to move freely between the upper and lower parts of the rotor (141). A pin-shaped stopper 1251 fixed to the piston rod (2) is provided in the notch (241).
protrudes and regulates the amount of rotation of the rotor (14). Note that this rotor (14) is not provided with the above-mentioned rotational force generating grooves or oil passages.

The rotor (13) with the above-mentioned rotational force generation groove (231 and rotational spring α6 of fang 1) and the rotor a4J without rotational force generation groove and rotational spring (161 (lη) each have their own frequency characteristics. A vibration system is constructed, and the oil hole (18α) provided in the rotor α31K is
) (18A) is communicated or disconnected from the oil passage I20) end of the piston rod (2). Further, when oil flows into the rotational force generating groove (23), the rotor 131 is urged clockwise or counterclockwise depending on the direction of the oil flow, and the rotation of this rotor (131)
is transmitted to the rotor (141) via the rotation spring (16).

Now, in this excitation vibration system with two degrees of freedom, the rotor (1
31 (141 moment of inertia and spring (16) (
By arbitrarily selecting the spring constant of 17), the rotation angle of the rotor 131 (14) can have the characteristics shown in Fig. 6. That is, the curve Q/ is the rotation angle of the rotor (13) to which the rotational force is applied by the fluid force, and θ/=θ/(1;l Sinωf, and the curve Q
2, 'f:, m is the rotation angle of the rotor 1141 to which no rotational force is applied due to physical strength, θ knee θrsinωf. Each of these rotation angle characteristics corresponds to the first resonance angular frequency ω of the two-degree-of-freedom system.
) and the direction of the force applied near the second resonance angular frequency ω, the rotation angle of each rotor (131 (14)) switches from positive to negative.

In this invention, the two rotational amplitudes of the rotor (13+ (14)) are given frequency dependence, so that the angular frequency ω is set to ωCrl<
By reducing the damping force in the region of ω ω cr 2 s ω C γ 3 <ω 0 m, the vibration amplitude of the vehicle body with mass m is effectively suppressed as in other regions.

Next, the operation of the hydraulic shock absorber having the above configuration will be described.

A case will be described in which the damping force generated at the leaf vane knob (9) of the piston portion (3) is made frequency-dependent due to the extension stroke and pressure stroke of the piston rod (2). In addition, the moment of inertia of the rotor f131 (14) and the rotational spring (161 (2
by appropriately selecting the rotation angle θ・of the rotor (131114).
amplitude θ10. A characteristic as shown in fang 5 is given to θ in advance.

During the extension stroke of the piston rod (2), the piston (3) moves up inside the cylinder (1), so the oil in the oil chamber A flows into the rotational force generating groove (23) and the oil hole (1o) of the rotor (13).
), pushes open the leaf valve (9), and further flows into the oil chamber B through the oil hole (7) of the piston (3). At this time, damping force is generated only by the leaf valve (9).

On the other hand, as the oil flows through the rotational force generation groove C31, a rotational force is generated in the rotor (131) in the L direction of Fig. O8. Also, the rotation angle θ of the rotor σ3 has the characteristics shown in Fig. O6. Therefore, until the angular frequency ω reaches O〈ω〈ωcr/, the oil passage (18
The angular displacement of α) is also θ. This is the piston (
There is no communication with the oil passage (20) provided in 2). Therefore, at 0〈ω〉ωCγ/, all the oil in the oil chamber A pushes open the leaf valve (9) and flows into the oil chamber B, and the damping force generated at this time performs a buffering operation, as shown in Fig. 7. It has a good amplitude characteristic. At this time, the rotation is also transmitted to the rotor (14J) via the rotational spring α force of the fang 2, and the rotor (14J) rotates with a delay like QYU.

The vibration angular frequency ω is ω. In the region where Al<ω<ω/, the rotational force acting on the rotor (13) when oil passes through the rotational force generation groove C31 of the rotor 131 and the spring constant of the first rotational spring f16) are Based on the relationship, this rotor (13) further rotates clockwise as shown in FIG. Oil passage (18α) (20
) are connected. For this reason, oil iA is applied to the outer periphery of rotor a4), the notch of rotor a31, and the oil passages (18α) (2o).
Flows into oil iB through. Therefore, the oil flows bypassing the leaf valve (9), and the damping force is greatly reduced.

In addition, in the region of ω7〈ω〉ωc, r, 2, the direction of the amplitude suddenly reverses as shown in Fig. 6, and the direction in which the force is applied and the direction of rotation of the rotor (131) become opposite, and the As shown in Figure (d), the oil passage (18h) of the rotor (13) communicates with the oil passage node.Thus, the damping force decreases in the region of ωcr<ω and ωc2, and the vehicle body shakes in this region. The width will be kept small.

Next, the vibration angular frequency ω is ω. When γλ〈ω〈ω0γ3, due to the moment of inertia and spring constant of the rotor (14J), the rotational force of the rotor (14) is also applied, and the rotor 0
3) rotates from counterclockwise to clockwise as shown in Figure 8(g), and communication between oil passages (18h) and (20) is cut off. Therefore, the flow of oil through these oil passages (18h) and (20) is stopped, and the oil in the oil chamber A flows into the oil chamber B via the leaf valve (9), increasing the damping force. However, ω of the rotor (13). The rotation in the region r3 < ω is as shown in Fig. 8 (f), and the oil passage (
18α) is brought into communication with the oil path +20)VC, and the damping force is reduced again.

That is, the vibration amplitude α of the mass m2 is O×ω×ω,
In γl, the curve P2 of Fang 2 is selected, and ω0γ/〈ω×ω. In γ, the 7'/curve of Fang 2 is selected, and ω0γyukuωkuω. In γ3, 22 curves in the 1r-2 diagram are selected,
At ω0γ3, ω, 2 (-0m), the same <Pi convex curve is selected.

Note that when the oil passages (18α) (18h) and the oil passage I20) are communicated or disconnected, the damping force changes greatly, and the swinging motion of the vehicle body, which is the mass, changes suddenly, resulting in poor ride comfort of the vehicle. To prevent this, each oil passage (18a) (18b)
(20) The end may be a tapered surface whose diameter gradually changes.

Next, when the piston rod (2) enters the pressure stroke, the piston (3) moves up inside the cylinder (1), so the oil in the oil chamber B passes through the oil hole (7) and enters the leaf valve (9). the gap between the leaf valve (9) and the supporting surface of the leaf valve (9) of the piston (3), the notch (12) of the valve stopper (4), and the rotational force generating groove (291t3) of the rotor (131).
It flows into oil chamber A through cl. At this time as well, a damping force is generated by the leaf valve (9) as described above. on the other hand,
As oil flows through the rotational force generating groove f23+, the rotor (131) is urged to rotate in the opposite direction to the above.

Note that the control operation of the vibration system is exactly the same as in the case described above. In addition, the critical angular frequency when oil flows from oil chamber B to oil chamber A is ωC'7/ @ω0γko, ω0γ'3゜ωJ
By selecting values different from the above-mentioned limit angular frequencies ω, γ, and γ3°, or by giving nonlinear characteristics to the rotating spring/16)(lη, the extension stroke and compression stroke can be differentiated. It becomes possible to provide different swing width characteristics.

In addition, (a) the hydraulic shock absorber is configured so that the damping force is frequency-dependent only during the bending stroke of the piston rod (2), and the damping force is determined only by the excitation speed during the compression stroke. , C port) Make the damping force frequency dependent only during the compression stroke of the piston rod (2), and do not generate damping force in the piston part during the compression stroke, or create the same damping force as in → (B). However, it is possible to make the damping force during the extension stroke of the piston rod (2) frequency dependent up to an arbitrary high frequency range, and in this case, each rotor (131 (14) The included vibration system is given the characteristics of rotational angle amplitude θ10 and θyu shown in Fig. 5, and the amplitude α is given as shown in Fig. 6, and the amplitude α is set in two regions where damping force is not required. It is possible to actively try to reduce the

In addition, the above configuration has a conventional hydraulic shock absorber with a rotor (131(
14), it is easy to assemble the parts, and the desired purpose can be achieved at low cost. In addition, when obtaining the same moment of inertia as the rotor f131 (1(a)) of the above embodiment by providing the vibration system mainly consisting of each of the rotors (131fl, 11) below the piston ζ3, that is, on the oil pressure B side, The thickness of the rotor itself can be reduced, and the overall length of the shock absorber can be shortened.

Note that the rotational force generating groove (23) is provided at an angle,
The opening diameter can be made different between the oil inflow side and the oil outflow side, or it can be gently curved.

Also, the rotor (13) is used instead of the rotational force generating groove (23).
The rotor (13
) can be provided with vanes for generating rotational force, which are rotary blades.

In addition, in the above, the rotor (131 is connected to the piston rod (21) via the rotation spring (161), but the rotor (131 is made free with respect to the piston rod (2) side, and the rotor I is connected to the rotation spring (161). When connected to the piston rod side through
In the region <ω×ωcr2, Fang 7 and 8 (,9)
As shown in the figure, rotor 03) is in the opposite direction to the upper rudder.

When ω>ωcr3, the oil passages (18b) and (20) communicate with each other and act to attenuate the damping force in the same manner as described above.

As explained above, according to the present invention, two rotors are connected to each other by the rotation spring of fang 2, one of these rotors is connected to the piston rod side via the rotation spring of rice 1, and one of the rotors is connected to the piston rod side via the rotation spring of rice 1. A vibration system is formed using the rotational force of each of the rotors as an excitation source, which is generated by oil flowing through the rotational force generation flow path formed in the rotor, and the piston is activated according to the frequency characteristics of this vibration system. The oil in the two divided oil chambers is configured to flow through the piston rod and the bypass flow path, which is an oil path provided in the rotor of the above-mentioned 1, or to cut off the flow, so that the oil has a damping means. Even in the vibration system, the damping force is reduced or not generated in the set angular frequency range, and the vehicle body vibration can be effectively suppressed over a wide angular frequency range, further improving the ride comfort of the vehicle. There is an effect.

[Brief explanation of the drawing]

Figure 1 is a model diagram of a two-degree-of-freedom vibration system, Figure 2 is a diagram of the amplitude characteristics of its mass, Figure 3 is a vertical cross-sectional view of the hydraulic shock absorber of this invention, and Figure 4 is the X in Figure 3. - X-ray cross-sectional view, Figure 5 is the same < Y-Y cross-sectional view, Figure 6 is the rotor rotation angle characteristic diagram, +-7 is the same amplitude characteristic diagram, Figure 8 (α) (h)
(C) (d) (g) (f) (g) (A) is an explanatory diagram showing sequentially the rotational displacement vibration according to the angular frequency of the rotor (131). (1)... Cylinder, ( 2)...Piston rod,
(3)... Piston, (9)... Leaf valve, (
13114)... Rotor, (16) σD... Rotating spring, (18α) (18A) C20)... Oil path, C23
)...Rotating force generation groove. Representative Patent Attorney Izumi Amano No. 8 27' Procedural amendment (spontaneous) February 2, 1980 Kazuo Wakasugi, Commissioner of the Japan Patent Office 1, Indication of the case 1982 Patent/Application No. 206534 2, Name of the invention Hydraulic Buffer 3, Relationship with the amended person case Patent applicant address 7 (092) x511Pk & * d. 4 Agent 5, Subject of amendment 3) “Brief explanation of drawings” column of the detailed description 1) Specification discrepancy 1
The statement in the scope of claims column on the page is corrected as shown in the attached sheet. 2) On page 4, 2, line 19 of the Mei MB book, the words ``sprung'' are corrected to ``unsprung.'' 3) On page 2 of the specification, line 20, the word "sprung" is corrected to "sprung". 4) On page 5 of the specification, line 15 to line 16, the phrase ``constitutes two vibration systems, and these plane vibration systems'' is changed to ``constitutes a vibration system with two degrees of freedom, and this vibration system''. correct. 5) On pages 2 and 8 of the specification, lines 18 to 19, the statement ``in the lower part of the rotor Q41'' is corrected to ``in the lower part of the rotor 04)''. 6) On page 9, line 8 of the specification, ``Rotating spring (te+ (71 J) is corrected to ``rotating spring αL''. 7) On page 9, line 16 of the specification, [Rule 1] Rotating spring (I
Correct "J" to "Fang 2 rotation spring 07)". 8) In the second line of page 10 of the specification, [Curve Q/j] is written as “
``Curve θl'', and in the second and fourth lines, ``Curve QxJ'' is corrected to ``Curve θλ''. 9) On page 10 of the specification, line 4, “θ/−θ1oSinω
f" was corrected to "θ/-θ7oSinωt", and in the 6th line of the same line, "θλ-θλ□ sinωf" was corrected to "θ/-θ7oSinωt".
λ−・θ−! "OSinωt," he corrected. 10) Specification page 10 > line 200 “Piston part (3)
``Leaf valve (9)'' is ``Piston part (3)''
I am corrected. U) On page 11 of the specification, line 5, IE-5J is written as "]
Figure 16” is corrected. 12) On the fourth line of page 12 of the specification, it says, "The swing width characteristic as shown in Figure 7". "The swing width a2 of the spring mass displacement is the swing width characteristic as shown in Figure 7." correct. 13) In the 6th line to the 7th line of page 12 of the specification, the phrase ``Rotation is transmitted, -1111 rotation.'' is corrected to ``Rotation is transmitted.'' 14) Specification Di (・Page 12, lines 1-8, “ωcri
＜ω〈ω/'' is corrected to [ω('7/ <ωkuω/''. 15) In the fourth line of page 13 of the specification, it should be ``ω.A〈ω〈ωCλ
'' is corrected to ``ωCr/ <ωkuωCγko.'' 16) On page 13 of the specification, line 7, “ω.τλkuω〈ωc
r3 J is corrected to ``ω(Wyu〈ωくω.r,yJ.'' 17) Specification E, page 13, line 19, ``vibration amplitude α'' is replaced with ``vibration amplitude a, 2” is corrected. 18) In the first line of page 14 of the specification, “ωCr/ <ω〈ω
Cr2'' was corrected to ``ωCr/ <ω7ωcrλ'', and the second line of the same line was ``ωtyr2'<,ωkuω.ryo''.
Correct the statement to ``ω0rλ〈ωくω.r3.'' 19) On page 14 of the specification, from line 17 to line 18, it says, ``In this case too,''. It is easy to make the damping force occur in the piston during the stroke. In that case, it is corrected to ``in the pressure stroke.'' 21) In the 12th line of page 15 of the specification, ``(b) Piston rod (2)'' is corrected to ``(b) Piston rod (2) as in the embodiment shown in Figure 3.'' On page 15 of the specification, from line 14 to line 18, it says, "It is possible to prevent the generation of damping force," instead of "it is possible to prevent the generation of damping force." It is possible,” correct. 22) In the 1st line of page 16 of the detailed statement, “Fengin a” is written in the 2nd line of the statement.
Correct the statement to read "Furiwakin A2". 23) Mei Aa/J', page 17, line 5, “ωcr/<
24) In the specification, page 17, lines 6 to 8, it is written as ``Rotor (13) is As shown in Figure 8 (A),
Correct the statement to read, ``The rotor 03) rotates, and when ω>ωCr3, ``becomes as shown in Figure 8 (h).'' 25) Meikunsho, page 18] - On the 12th line, it says "Similarly, the amplitude characteristic diagram" [The amplitude characteristic diagram of mass 771,2 in Figure 1]
I am corrected. 26) On page 18 of the specification, line 13, the phrase "rotational displacement vibration" is corrected to "rotational displacement motion." 27) Correct the figures 4, 7, and 8 as shown in the attached sheet. 2 Claims: The inside of the cylinder is divided into two oil chambers by a piston portion having a damping force generating valve, and the piston portion is provided at one end;
In the hydraulic shock absorber, the hydraulic shock absorber is provided with a piston rod that extends in and out of the cylinder force in a sealed manner, and the two ring-shaped rotors are rotatably inserted into the piston rod, and the two ring-shaped rotors are connected to each other. The rotation spring of fang 2,
A rotating spring of fang 1 connected to one of the rotors and the piston rod side, and an oil passage penetrating the inner and outer peripheries of either one of the rotors and having an open end communicating with one of the oil chambers. and a rotational force generating flow path penetrating above and below one of the rotors, and when oil flows through the rotational force generating flow path, the rotational force of the rotor generated is used as an excitation source. Two vibration systems are constituted, and in the predetermined excitation same wave frequency range of both vibration systems, there is a flow between the two oil chambers via the oil passage provided in the center of the piston rod and the oil passage provided in the rotor. A hydraulic shock absorber designed to allow oil to flow.

Claims (1)

[Claims] The inside of the cylinder is divided into two oil chambers by a piston part having a damping force generating valve, and the piston part is provided at one end,
A hydraulic shock absorber is provided with a piston rod that extends sealingly through the inside and outside of the cylinder, and is configured to reduce vibration amplitude applied to the piston rod and the cylinder, the hydraulic shock absorber being rotatable relative to the piston rod. Two fitted ring-shaped rotors, a rotation spring of fang 2 linked between these rotors, a rotation spring of fang 1 linked to one of these rotors and the piston rod side, and any of the above rotors. an oil passage penetrating the inner and outer peripheries of one of the rotors and having an open end communicating with one of the oil chambers, and a rotational force generating flow passage penetrating above and below one of the rotors; Two vibration systems are constructed using the rotational force of the rotor as an excitation source, which is generated when oil flows through the rotational force generation flow path, and in a predetermined excitation frequency range of both of these vibration systems, the center of the piston rod is A hydraulic shock absorber configured to allow oil to flow between the two oil chambers through an oil passage provided in the rotor and an oil passage provided in the rotor.