JPS63259239A - Vibration damper - Google Patents

Abstract

PURPOSE:To reduce a vibration damping apparatus in weight by sealing a liquid in a fluid chamber formed between a cylinder and a piston rod, and providing a partition wall supported by the cylinder or the piston rod and a small-diameter fluid passage for circulating the liquid to the outside. CONSTITUTION:A partition wall 4 elastically supported on a head portion 2a of a piston rod 2 through elastic material 3 is slidably inserted in a cylinder 1. A fluid such as water, oil or the like is sealed in a fluid chamber 5 formed between the partition wall 4 and the cylinder 1. Further, there is provided a small-diameter fluid passage 6 which is extended from the fluid chamber 5 to the outside and communicated with an accumulator 7. Accordingly, great damping force is generated without large mass to the vibration of a specified frequency by resonance phenomena by providing a vibration system formed by the liquid chamber 5, the partition wall 4 and the fluid passage 6 so as to reduce a vibration damping apparatus in weight.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vibration damping device for damping vibrations in vehicles, industrial machines, and the like.

(Prior Art) Conventionally, various vibration damping devices have been used in vehicles to damp vibrations. As a typical example, an oil damper provided between two members that are relatively displaced is generally well known (see Japanese Utility Model Publication No. 59-122450, etc.). This oil damper generates a damping force due to the flow resistance when oil passes through the orifice of the piston, and the damping force is equal to the square of the speed of the piston (that is, the relative speed between two members that are relatively displaced). However, when the piston speed increases to a certain extent, the orifice of the piston becomes closed and no damping force is generated.

In addition, as a device for particularly damping vibrations at a certain frequency, for example, as disclosed in Japanese Utility Model Application Publication No. 58-44222, a mass member of a predetermined mass is attached to the vibrating body via an elastic member, and the mass member A so-called dynamic damper is known that damps the imaging of a vibrating body by resonance.

(Problem to be solved by the invention) However, the vibration damping effect of the dynamic damper is determined by the mass ratio of the vibrating body and the mass member, and in order to achieve a large effect, the mass or weight of the mass member must be set large. There is a need to.

Therefore, when a dynamic damper is used in a vehicle to attenuate the vibrations of a particularly large vibrating body, there is a problem in that the weight of the vehicle increases significantly.

The present invention has been made in consideration of these points, and its purpose is particularly to provide damping at frequencies that are provided between two members that are displaced relative to each other like conventional oil dampers, and for which damping force cannot be generated by oil dampers. It is an object of the present invention to provide a vibration damping device that can generate a large damping force against vibrations with a smaller mass than a dynamic damper.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention includes a cylinder connected to one member as a vibration damping position V4 provided between two members with relative displacement, A fluid chamber in which fluid is sealed is formed between the piston rod connected to the other member, and a partition wall elastically supported by the cylinder or the piston rod, and a partition wall that allows the fluid in the fluid chamber to flow to the outside. The structure is such that a small-diameter fluid path that closes the gap is provided.

(Function) With the above configuration, in the present invention, a vibration system is configured by a fluid chamber in a cylinder, a partition wall provided in the fluid chamber in an elastically supported state, and a fluid path having a communication port to the outside of the fluid in the fluid chamber. Therefore, a damping force can be generated by the resonance phenomenon of the vibration system against vibrations of a specific frequency input from the cylinder or piston rod.

In this case, the cross-sectional area of the fluid chamber is △, and the cross-sectional area of the fluid path is a1
If we believe the question of the fluid in the fluid path, the equivalent image quality mm calculated by 194 times the mass of the mass member in the dynamic damper becomes M-A (A-a) m/a2. Here, the fluid path has a small diameter, and its cross-sectional area a is considerably smaller than the cross-sectional area A of the fluid chamber (a
Since <<A>, the equal image quality ff1M is much larger than the fluid quality In in the fluid path (M, >, >m).

As a result, a large damping force can be generated without requiring a large quality m compared to a dynamic damper (the ff1ffi of the entire device is comparable to that of a conventional oil damper).

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows the basic configuration of a vibration damping device according to the present invention, and this vibration damping device A consists of two members B+
, 82, and both members 8+.

A damping force is generated to suppress the relative displacement (vibration I of the displacement side member) at a specific frequency of B2. The vibration damping device A includes a cylinder 1 connected to one member 8I,
The piston rod 2 is connected to the other member B2. A partition wall 4 which is elastically supported by the head portion 2a of the piston rod 2 via elastic members 3, 3 is slidably inserted into the cylinder 1, and the partition wall 4 and the cylinder 1 are connected to prevent water and Fluid chamber 5 filled with fluid such as oil
is formed.

Further, the fluid chamber 5 is provided with a small diameter fluid path 6 extending outside from the fluid chamber 5, and one end of the fluid path 6 communicates with an accumulator 7. The accumulator 7 has a fluid chamber 9 and a gas chamber 10 separated by a diaphragm 8. The fluid chamber 9 communicates with the fluid passage 6 and is filled with the same fluid as the fluid chamber 5 of the cylinder 1. On the other hand, the gas chamber 10 is filled with gas at a predetermined pressure. Thus, a vibration system is constituted by the fluid chamber 5, the partition wall 4, and the fluid path 6, and the resonance phenomenon of this vibration system generates a damping force to damp vibrations at a specific frequency.

Incidentally, the accumulator 7 is not directly involved in the generation of damping force, but is used to absorb fluid in response to changes in the volume of the fluid chamber 5 as the piston rod 2 expands and contracts. In addition, in order to generate a damping force, instead of the partition wall 4, the head portion 2a of the piston [1] is slidably inserted into the cylinder 1 as a piston to form the fluid chamber 5. A vibration system may be constructed by disposing the partition wall 4 in a state where it is elastically supported by the cylinder 1.

FIG. 2 shows an embodiment in which the vibration damping device of the present invention is used as a steering damper for a vehicle.

The steering damper D is installed in the vicinity of the tie rod S1 of the steering structure S in a state extending in the vehicle width direction, and damps and suppresses vibrations transmitted from the front wheel H side, which is a steered wheel, to the steering handle S2 side.

In the steering damper D, as shown in FIG. 3, a piston 23 connected to a piston rod 22 is slidably inserted into a cylinder 21, and the cylinder 21 has the following features:
It has two fluid chambers 24a and 24b partitioned by the piston 23 and each filled with fluid. Further, the piston 23 has both the fluid chambers 24a and 24b@
A communicating orifice 25 is provided, and the piston 2
The fluid chamber 24b on the opposite side to the piston die extension side of No. 3 is
The side surface of the fluid chamber 24b opposite to the piston 23 is a partition wall 26.
is formed by. The partition wall 26 is connected to the cylinder 2
The cylinder 21 is slidably fitted into the support plate 27 fitted to the cylinder 21, and is held between both sides by springs 28 and 28, and is elastically supported so as to be displaceable in the axial direction of the cylinder 21.

Furthermore, a fluid chamber 30 and a gas chamber 31 partitioned by a diaphragm 29 are provided on the side where the partition wall 26 of the cylinder 21 is disposed.
An accumulator 32 is integrally formed, and a gas chamber 31 of the accumulator 32 is filled with gas at a predetermined pressure from a gas filling port 33.

A fluid chamber 24b whose side surface is formed by the partition wall 26
The fluid chamber 30 of the accumulator 32 is the partition wall 2G.
and is communicated with each other via a small-diameter communication pipe 34 as a fluid path provided through the support plate 27.

Next, to explain the operation of the steering damper D in the above embodiment, the piston rod 22 is connected to the cylinder 2.
When the piston 23 slowly expands and contracts with respect to 1, that is, when the piston 23 reciprocates within the cylinder 21 at low speed, the fluid in the fluid chamber 24a or 24b on the moving side of the piston 23 is
The other fluid chamber 2 passes through the orifice 25 of the piston 23.
4b or 24a, and a damping force is generated by the flow resistance at the orifice 25 at this time (the principle of generating this damping force is the same as in the case of a conventional oil damper). For this reason, the above-mentioned steering damper D prevents the occurrence of a kick-pack phenomenon in which the vibration vJ (gentle vibration #J with relatively large amplitude) when the front wheel 1 vibrates vertically due to unevenness of the road surface, etc. is transmitted to the steering wheel S2 side. This can be prevented by

On the other hand, when the screws 1 to 23 vibrate rapidly within the cylinder 21 with a small amplitude, the orifice 2 of the piston 23
5 is in a closed state. Steering damper D at this time
The vibration in will be explained below with reference to FIG. 4, which schematically shows the steering damper D.

Now, the cross-sectional area of the piston 23 (the cross-sectional area of the fluid chamber 248.24b) is A1, the cross-sectional area of the partition 26 is 81, the passage cross-sectional area of the communicating pipe 34 is a, the passage length of the communicating pipe 34 is 9, and the density of the fluid is ρ, the spring constant of the spring 28.28 supporting the partition wall 26 is 1, the spring constant of the gas chamber 31 of the accumulator 32 is 2, the pressure of the fluid chamber 24b is PA, the accumulator 3
Let Pa be the pressure in the first fluid chamber 30. 11 of the fluid in the communication pipe 34 is II-98. Furthermore, the equation of motion within the communication pipe 34 is: iV' + CV-(P^-Pa) a
・”(tl)

Further, if the displacement of the partition wall 2G is zl and the displacement of the diaphragm 29 of the accumulator 32 is 22, then from the balance between the spring force and the fluid pressure, k+Z+-(PA Pa)B-(2)k2z2
-PeA...The relational expression (3) holds true.

Furthermore, due to the incompressibility of the fluid, AX −Bz l −aV−0−(4)3z I +a
The relational expression y-AZ 2-0 = (5) holds true. However, X is the piston rod 22 or piston 2
The displacement of 3 is shown.

When VlPA and Ps are solved for X from the above equations (1) to (51), the following is obtained.

y-(Aa/B2) ・k+X/ (-m ω2+j ωc + (a 2 /[32)・
k+) ... (6) PA-
('(△/B2)・k t +(k 2 /A> )x
-(ak+ /B2)・[(Aa/B') ・k, x/(-m ω' +j (1)C+(a'/32
)・k+)] ...(Sword P
a-k2X/A...(
8) Furthermore, the transmission force Ft to the cylinder 21 when the piston 23 is excited by the displacement
) (PA - Pa) = (PA - Pa)
B+PB A+ (A-B-a > (PA-PB)
= (A a ) PA +a Ps. Furthermore, substitute the above (71, +81) into PA and PB of this formula, respectively,
When rearranging for X, Ft − [A (A-a)k I/[32+k 2(
A (A-a) k + /B") 2
(△ (A-a) (-m ω2+j ωC)/'a 2
+A(△-a)k+/B')-']x
= (Kl + 2 − + 2・ (−Mω2
+jωC+ + )−' ) x...(9). However, Kl −A (A−a) k + /B′Kz=kz M−A (A−a) m /a 2 C−A (Δ−a)c/a′.

The third term in the parentheses of the above equation (9) is the damping force term.

Further, M in 43 in this damping force term is an equivalent ff1til that is opposite to Mffi of the mass member in the case of a dynamic damper, and C is an equivalent damping coefficient that is opposite to the capital reduction coefficient in the case of a dynamic damper. Therefore, in the case of the steering damper D in the embodiment, the passage cross-sectional area a of the communication pipe 34 is significantly smaller than the cross-sectional area A of the piston 23 (a (<A), so the small number of fluid types 1 in the communication pipe 34 , it is possible to generate a large damping force similar to that of a dynamic damper with a large mass member.

Here, an example of the calculation result of the damping force is shown in the graph of FIG. However, in the four calculations of this damping horn, the excitation amplitude of the piston rod 22 (displacement X) is 0°2m111,
Further, the values of each component were set as follows.

A-1000mm2 B -800mm' a-4, OIIll112 R-100mm ρ-1,02X10-10-1O-s 2/mm4 (when the liquid is water) k + -20, Okgf /nm k 2-2. Okgf /mm C=Q, 2kgf -sea 7mm In this case, the quality of the fluid in the communication pipe 34 fin is 0°4gr
(4,08X10-5 grf-s' 7mm)
However, the equivalent image mass M is 24.9kc+.

This means that the overall weight of the steering damper D is about 1 kgf, which is the same as when it is made of a conventional oil damper, so the weight can be reduced to about 1/25 to obtain the same reduction force as in the case of a dynamic damper. means. In addition, as can be seen from Figure 5, there is a resonance region near the frequency @ 17.5Hz, and a large damping force is obtained, but this resonance region is due to the shimmy phenomenon that occurs when the vehicle is running at high speeds (80 to 130kIIl/h). When the frequency matches the frequency of one rib in the longitudinal direction of the front wheel H, which is the cause, the occurrence of the shimmy phenomenon can be effectively prevented with a large damping force.

In the above embodiment, the vibration damping device of the present invention is used as a steering damper D for a vehicle, but the present invention is not limited to this. Of course, it may also be used to damp vibrations in general industrial machinery.

(Effects of the Invention) As described above, according to the vibration damping device of the present invention, the fluid chamber in the cylinder, the partition wall elastically provided in the fluid chamber, and the fluid path that allows the fluid in the fluid chamber to circulate to the outside, Due to the resonance phenomenon of the constructed vibration system, it is possible to generate a large damping force without requiring a large mass compared to a dynamic damper, and it is particularly advantageous for vibration countermeasures for vehicles where there is a strong demand for weight reduction. It is something.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a schematic diagram showing the basic configuration of a vibration damping device, and FIG. 2 is a perspective view showing the arrangement of a steering damper in a vehicle.
FIG. 3 is a longitudinal sectional side view of the steering damper. Fourth
The figure is a schematic diagram for explaining vibrations in the steering damper J3, and FIG. 5 is a graph showing the calculation results of the damping force. 1.21...Cylinder, 2.22...Piston rod, 2,28...Elastic part U (spring), 4.26
...Partition wall, 5, 24b...Fluid chamber, 6, 34...
Fluid path (communication pipe). Figure 1 Figure 2

Claims (1)

[Claims] (1) A vibration damping device provided between two relatively displaced members, which includes a fluid chamber in which fluid is sealed between a cylinder connected to one member and a piston rod connected to the other member. A vibration damping device characterized in that the fluid chamber is provided with a partition wall elastically supported by the cylinder or piston rod, and a small-diameter fluid path for allowing fluid in the fluid chamber to flow to the outside.