JPH0247613B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a system for damping vibration input from a vibrating body such as an engine or a power unit using a damping force caused by passage of a fluid through a constriction. , relates to a device that prevents the vibrations from being transmitted to a support such as a vehicle body.

[Conventional technology]

As a conventional fluid-filled vibration isolator, for example, the first
There is one as shown in the figure (described in Japanese Patent Application Laid-open No. 72741/1983). That is, a rubber-like elastic body 4 is arranged between the frame body 1 on the vibrating body side and the frame body 2 on the support body side, which changes the volume of the internal fluid main chamber 3 by relative movement of both the frame bodies 1 and 2. A fluid sub-chamber 5 whose volume changes in accordance with a change in the volume of the fluid main chamber 3 is provided in the main fluid chamber 3 through throttles 7 and 8 formed in a partition 6 supported on the frame body 2 side. The fluid 9 moves between the main fluid chamber 3 and the auxiliary fluid chamber 5 via the throttles 7 and 8, thereby damping vibration input. The apertures 7 and 8 have different inner diameters and lengths, and have different damping characteristics. 1
0 is a diaphragm for defining the fluid sub-chamber 5, and is configured to change its shape in accordance with changes in the volume of the fluid sub-chamber 5.

Thus, the volume of the main fluid chamber 3 changes due to the vibration input from the frame 1 side, and the fluid 9 moves between the main fluid chamber 3 and the sub-fluid chamber 5, and at this time, the fluid 9 moves through the throttle 7, 8, the vibration input is attenuated. The damping characteristic obtained here is a combination of the damping characteristic due to the diaphragm 7 and the damping characteristic due to the diaphragm 8, and has two peaks, and is shown by a solid line in FIG. 2. Second
The chain line in the figure indicates the vibration transmission force, which is the vibration transmitted to the frame 2 without being attenuated by the apertures 7 and 8. IV in Fig. 2 is the idling vibration range of the engine.

FIG. 3 is a schematic diagram of FIG. 1, where ma is the mass due to the fluid mass in the aperture 7 and the diaphragm 10, mb is the mass due to the fluid mass in the aperture 8 and the diaphragm 10, and ka is the mass due to the fluid mass in the aperture 8 and the diaphragm 10. , the stiffness of the diaphragm 10, kb is the stiffness of the rubber-like elastic body 4, ca
indicates the damping force of the diaphragm 7, and cb indicates the damping force of the diaphragm 8.

However, in such a conventional fluid-filled vibration isolator, the volume of the fluid main chamber 3 and the volume of the fluid subchamber 5 are common to both the throttles 7 and 8, and the diaphragm 10 and the elastic body Stiffness ka of 4,
Since kb is the same, the range for tuning the vibration input damping characteristics of the vibration isolator is likely to be limited. For this reason, for example, the engine's vertical vibration range is generally around 10Hz, the steering resonance range is generally around 30Hz, and the engine's idling vibration range is generally around 20Hz.
30Hz, but as shown in Figure 2, if the peak of the damping force is set to about 10Hz, there is a problem in that it becomes difficult to set a sufficient damping force in the idling vibration region IV and steering resonance region. .

The present invention has been made by focusing on such conventional problems, and by forming a plurality of fluid sub-chambers that are continuous to the fluid main chamber via a restriction, the fluid sub-chambers are connected to the fluid main chamber via a restriction. By installing the next chamber and the diaphragm independently of the others, it is possible to set the multiple peaks of damping force to suit the vibration range to be damped, thereby solving the above-mentioned conventional problems. The purpose is to

[Means to solve the problem]

In the present invention, a rubber-like elastic body is disposed between a frame on the vibrating body side and a frame on the support side, and changes the volume of an internal main fluid chamber by relative movement of both frames, and the main fluid chamber is The two fluid sub-chambers whose volume changes in accordance with the volume change of the fluid main chamber are connected via two throttles individually fixed to both frames, and each throttle is connected to the fluid main chamber. The present invention relates to a fluid-filled vibration isolator in which a fluid passage between a hole on the chamber side and a hole on the fluid sub-chamber side is extended by meandering and the cross-sectional area of the fluid passage is increased.

[Effect]

Due to a change in the volume of the main fluid chamber due to the vibration input, the fluid moves between the fluid main chamber and the secondary fluid chamber through the restriction, and at this time, the fluid passes through the restriction, thereby attenuating the vibration input. In particular, in the present invention, since a plurality of fluid sub-chambers are formed in parallel with the fluid main chamber, a plurality of fluid sub-chambers are formed independently of each other, and each is directly connected to the fluid main chamber via the aperture. Since they are supposed to communicate individually, the damping force provided by each aperture can be set independently and individually, and therefore the damping force of both apertures does not interfere with each other. .

Moreover, since both fluid sub-chambers are directly connected to the main fluid chamber via a throttle, the fluid receives vibration input due to volume changes in the main fluid chamber without the volume changes being absorbed at either position. pass through one of the apertures corresponding to the frequency of . For this reason,
Even when there is a minute fluid pressure change such as idling vibration, the fluid always passes through a throttle that matches the vibration frequency.

Further, in the present invention, since the fluid passage of each throttle is meandering, the length can be increased, and the cross-sectional area of the fluid passage is increased, so that the resonance level in the low frequency vibration region can be increased. can be made large.

〔Example〕

The present invention will be explained below based on illustrated embodiments. 4 to 8 are diagrams showing a first embodiment of the present invention, and show an example in which the present invention is applied to a vibration isolating device for a power unit such as an engine.

First, to explain the structure, numeral 11 is a frame on the power unit side which is a vibrating body, and numeral 12 is a frame on the vehicle body side which is a support. A partition plate 13 is fixed to the frame 11, and the portion of the partition plate 13 excluding the first aperture 14 formed in the center substantially forms a part of the frame 11. In addition, the frame body 12 includes an auxiliary frame 15 and a partition plate 1.
6 are fixed, and the auxiliary frame 15 is substantially the frame body 12.
form part of A second aperture 17 is formed on the partition plate 16 .

The above-mentioned partition plate 13 that substantially forms the frame 11
A rubber-like elastic body 18 is vulcanized and bonded between the auxiliary frame 15 that substantially forms the frame 12, and the first aperture 14 and the second aperture 17 are formed inside the rubber-like elastic body 18.
A main fluid chamber 19 is formed between the two. Partition plate 13
A first fluid subchamber 21 whose upper surface is defined by a diaphragm 20 is formed on the upper side, and a partition plate 16
A second fluid sub-chamber 23 whose lower surface is defined by a diaphragm 22 is formed below the diaphragm 22 .

An air chamber 24 is formed between the frame body 11 and the diaphragm 20, and this air chamber 24 communicates with the atmosphere through an air hole 25 opened in the frame body 11. Furthermore, an air chamber 26 is provided between the frame body 12 and the diaphragm 22.
is formed, which communicates with the atmosphere through air holes 27 opened in the frame 12.

As shown in FIGS. 4 and 5, the first diaphragm 14 is a plate body 14a fixed to the partition plate 13 with a gap therebetween.
, the hole 14b opened in the partition plate 13, and the plate 1
4a, and a meandering passage 14d formed between the partition plate 13 and the plate body 14a, connecting the holes 14b and 14c and meandering. The structure of the second throttle 17 is similar to that of the first throttle 14, but its holes 14b, 14C and meandering passage 14d
The length and size of the first diaphragm 14 are different from those of the first diaphragm 14, and the diameter and length of the diaphragms 14 and 17 are substantially changed so that the damping forces are different.

The fluid main chamber 19, the first fluid sub-chamber 21, the second
The fluid subchamber 23 is filled with liquid, and this liquid is communicated with each chamber 19 , 21 , 23 via the first restrictor 14 and the second restrictor 17 .
Further, the rigidities of the diaphragms 20 and 22 are made different from each other.

Next, the action will be explained.

When the vertical vibration of the vibrating body is input from the frame 11, the partition plate 13 vibrates together with the frame 11, causing the rubber-like elastic body 18 to expand and contract. Then, the fluid main chamber 19
The volume of the fluid expands and contracts, and the liquid moves back and forth between the main fluid chamber 19, the first fluid sub-chamber 21, and the second fluid sub-chamber 23 via the first restrictor 14 and the second restrictor 17 each time. occurs. When the liquid passes through the first aperture 14 and the second aperture 17, each aperture 14,
17, the vibration energy is converted into thermal energy by this resistance and the vibration is damped. In this way, the vibrations input to the frame body 11 are not transmitted to the frame body 12, or vibrations that have been damped and become weaker are transmitted to the frame body 12.

When the volume of the main fluid chamber 19 is reduced, the liquid therein moves to the first sub-fluid chamber 21 and the second sub-fluid chamber 23, so that the volumes of both sub-chambers 21 and 23 increase. At this time, diaphragms 20 and 22
deforms toward the side farther from the main fluid chamber 19 to allow the increase in volume. At this time, air chamber 2
The change in volume of holes 25 and 26 is allowed by air escaping to the outside through holes 25 and 27.

Figure 6 is a model diagram of Figure 4, Figure 8 is a model diagram of Figure 4.
In FIG. 8, ke is the rigidity that supports the liquid in the main fluid chamber 19, and cc is the first constriction 14.
, cd is the damping force of the second diaphragm 17, mc is the mass due to the liquid mass in the first diaphragm 14 and the diaphragm 20, md is the mass due to the liquid mass in the second diaphragm 17 and the diaphragm 22, kc is the The stiffness of the diaphragm 20, kd, is the stiffness of the diaphragm 22. By appropriately setting the damping force, mass, and rigidity, the characteristics of the vibration isolator become as shown in FIG. 7.

In FIG. 7, the solid line shows the change in damping force, and the chain line shows the change in vibration transmission force. IV is the engine's idling vibration range. The aim of a vibration isolator with such characteristics is to generate peak damping force at different frequencies, for example, to increase the damping force around 10Hz, which is the vertical vibration of the engine, and around 30Hz, which is the steering resonance. The purpose is to reduce the vibration transmission force in the normal idling vibration range IV. In this figure, the vibration transmission force decreases in a frequency range slightly lower than that where the damping force reaches the peak on the right side, that is, the idling vibration range IV, and the damping force increases around 10Hz and 30Hz. The above aim has been achieved. To achieve this aim, this embodiment has two mutually independent sub-chambers 21 and 23 for the main fluid chamber 19;
Each aperture 14, 17 and each diaphragm 20, 22
This is because the damping forces of the throttles 14 and 17 and the rigidities of the diaphragms 20 and 22 are made different.

〔Effect of the invention〕

As explained above, according to the present invention, a plurality of fluid sub-chambers are formed in parallel to the main fluid chamber, so a plurality of fluid sub-chambers are formed independently of each other, and each of the fluid sub-chambers is formed independently of the fluid main chamber. The damping force provided by each throttle can be set independently and individually, so that the damping force caused by both throttles is directly and individually communicated with the main fluid chamber. There will be no interference. For this reason,
Since it is now possible to set a plurality of damping force peaks to suit the vibration range to be damped, it is possible to damp all vibration inputs at each frequency.

Moreover, since both fluid sub-chambers are directly connected to the main fluid chamber via a throttle, the fluid receives vibration input due to volume changes in the main fluid chamber without the volume changes being absorbed at either position. pass through one of the apertures corresponding to the frequency of . For this reason,
Even when there is a minute fluid pressure change such as idling vibration, the fluid always passes through a throttle that matches the vibration frequency, which has the effect of reliably damping the vibration input.

by the way, Since there is a relationship between fluid resonance level {tan δ) max} ∝ diaphragm cross-sectional area, in order to obtain a large fluid resonance level {tan δ) max} in low-frequency vibrations, the diaphragm cross-sectional area should be increased and the diaphragm cross-sectional area should be increased. The length also needs to be increased.

Therefore, in the present invention, by configuring each throttle by meandering the fluid passage between the hole on the fluid main chamber side and the hole on the fluid subchamber side, it is possible to realize an extension in length. Since the cross-sectional area of the fluid passage is increased, the resonance level in the low frequency vibration region can be increased.

In addition, since each throttle of the present invention is individually fixed to the frame on the vibrating body side and the frame on the support side, even if there is a minute change in fluid pressure in the main fluid chamber such as idling vibration, the fluid The resonance level can be increased.

Therefore, in the present invention, the damping efficiency of vibration input can be improved.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the conventional example, Fig. 2 is a graph showing the characteristics of vibration transmission force and damping force of the conventional example, Fig. 3 is a schematic diagram of Fig. 1, and Fig. 4 is the first example of the present invention. 5 is an enlarged cross-sectional view taken along the line V-V in FIG. 4, FIG. 6 is a model diagram of FIG. 4, and FIG. 7 is a cross-sectional view of FIG.
FIG. 8 is a graph showing the characteristics of vibration transmission force and damping force in the example, and is a schematic diagram of FIG. 4. 11... Frame on the vibrating body side, 12... Frame on the support side, 13, 16... Partition plate, 14, 17... Diaphragm, 15... Auxiliary frame, 18... Rubber-like elastic body, 1
9...Fluid main chamber, 20, 22...Diaphragm,
21, 23...Fluid subchamber, 24, 26...Air chamber.

Claims (1)

[Claims] 1 Between the frame on the vibrating body side and the frame on the support side,
A rubber-like elastic body is arranged to change the volume of an internal main fluid chamber by relative movement of both frames, and the main fluid chamber has two sub-fluid chambers whose volume changes in response to changes in the volume of the main fluid chamber. The secondary chambers are connected through two throttles individually fixed to both frames, and each throttle is connected to the fluid passageway between the hole on the main fluid chamber side and the hole on the side of the fluid subchamber in a meandering manner. A fluid-filled vibration isolator characterized in that the fluid passage is extended by increasing the cross-sectional area of the fluid passage.