JPH0689808B2 - Anti-vibration device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration device used as, for example, a bush for automobiles, member mounts, cab mounts, and the like. It provides effective absorption of small amplitude vibrations and adequate damping of low frequency large amplitude vibrations.

(Prior Art) As a conventional device of this type, for example, Japanese Patent Laid-Open No. 60-18
There is an elastic bushing disclosed in Japanese Patent No. 4741.

This elastic bush, as shown in FIG.
The inner cylinder 1 and the outer cylinder 2 are interconnected by an elastic body 3, and one fluid chamber 4 in which a fluid is annularly enclosed is formed in the elastic body 3 between the inner and outer cylinders, and this fluid chamber Four
Is divided into two small chambers 4a, 4b which are separated in the axial direction by an orifice ring 5 which can be displaced relative to the inner and outer cylinders 1, 2 in the axial direction thereof, while the small chambers 4a, 4b are separated.
Are communicated with each other by the orifice 6 provided in the orifice ring 5, and the inner and outer cylinders 1, 2 are connected to the outer circumference of the inner cylinder 1.
It is configured by providing a stopper sleeve 7 that regulates the relative displacement amount of the orifice ring 5 with respect to the predetermined range.

In such an elastic bush, for example, when a small-amplitude vibration oriented in the axial direction is transmitted to the inner cylinder 1,
Under the deformation of the elastic body 3, the inner cylinder 1 and the stopper sleeve 7
When and are relatively displaced in the axial direction with respect to the orifice ring 5 and the outer cylinder 2, the vibration of the outer cylinder 2 is insulated from the outer cylinder 2, and when a large amplitude vibration is transmitted to the inner cylinder 1. Is the inner cylinder 1 and the stopper sleeve 7,
The relative displacement with respect to the outer cylinder 2 together with the orifice ring 5 that is engaged with the shoulder portion of the stopper sleeve 7 causes the fluid to flow through the orifice 6 between the two small chambers, thereby damping the vibration.

(Problems to be solved by the invention) However, in such a conventional technique, since the orifice ring 5 that contributes to the insulation of the small-amplitude vibration also serves as the partition wall of both small chambers 4a and 4b, for example, Inner and outer cylinders 1, 2
Due to relative displacement in a direction intersecting with, for example, an orthogonal direction to, the axial direction of the inner ring 1, the orifice ring 5 is in contact with the peripheral surface of the stopper sleeve 7 at any position in the peripheral direction. When the small amplitude vibration in the axial direction is transmitted, the inner cylinder 1 and the stopper sleeve 7
Cannot be displaced independently of the orifice ring 5, and these displacements also cause the displacement of the orifice ring 5, so that the dynamic spring constant of the device is increased and the vibration isolation function is sufficiently improved. There was a problem that it could not be exhibited.

Further, in this conventional device, since both the orifice ring 5 and the stopper sleeve 7 are made of an elastic material, it is extremely difficult to accurately specify the relative displacement amount of the orifice ring 5 with respect to the stopper sleeve 7. In addition, since the relative displacement amount increases due to wear, fatigue, thermal deformation, etc. of the orifice ring 5 and the stopper sleeve 7, it is substantially possible to cause the device to exhibit desired vibration damping performance. There was a problem that it was impossible.

The present invention advantageously solves the above-mentioned problems of the prior art, and provides a vibration isolator capable of always sufficiently exhibiting a vibration isolation function for small amplitude vibrations and a vibration damping function for large amplitude vibrations. is there.

(Means for Solving Problems) According to the present invention, a high-rigidity inner cylinder and an outer cylinder are interconnected by an elastic body made of rubber or a rubber-like elastic material, and a liquid is sealed between these inner and outer cylinders. To form one or a plurality of fluid chambers that are continuous or spaced apart in the circumferential direction, and preferably, each of the fluid chambers of the inner and outer cylinders is separated by a partition wall fixed to either the inner cylinder or the outer cylinder. While dividing into two small chambers that are separated in the axial direction, this is also preferably a vibration damping device in which both small chambers communicate with each other by at least one throttle passage provided in a rigid member, wherein the partition wall has an annular elasticity. A portion and a rigid portion inscribed or circumscribed in the annular elastic portion are provided, and a valve member slidable over a predetermined amount in the axial direction of the inner and outer cylinders is arranged in the rigid portion.

(Operation) In this vibration isolator, for example, when high frequency small amplitude vibration in the axial direction is transmitted to the inner cylinder, the inner cylinder is
Under the deformation of the elastic body, the elastic body is displaced in the axial direction relative to the outer cylinder independently of the partition wall or together with the partition wall. At this time, the valve member vibrates with a good response to the rigid portion of the partition wall to compensate for the volume change of the small chambers, so that there is no pressure difference between the liquids in the small chambers and the throttle passage. There is also no flow of liquid through.

Therefore, the high-frequency small-amplitude vibration is sufficiently effectively insulated from the outer cylinder without increasing the dynamic spring constant of the device.

Note that, here, the relative displacement of the inner and outer cylinders in the direction intersecting their axial direction allows the sliding movement of the valve member even if the partition wall is pressed against the peripheral surface of the inner and outer cylinders at any part in the circumferential direction. Is always sufficiently secured by the rigid portion of the partition wall that is not subject to deformation due to the pressing force, so this device can sufficiently generate high-frequency small-amplitude vibration even in the relative displacement state of the inner and outer cylinders. It can be insulated.

Also, when low-frequency large-amplitude vibration in the axial direction is transmitted to the inner cylinder of this device, the volume change of both small chambers should be compensated only by the sliding movement of the valve member due to the displacement of the inner cylinder. As a result, a pressure difference is generated between the two small chambers, so that the flow of the fluid in the small chamber through the throttle passage is brought about and the vibration is damped.

Here, since this vibration damping is brought about at the sliding stroke end of the valve member, which is also preferably made of a rigid material, with respect to the rigid portion of the partition wall, the sliding stroke of the valve member with respect to the partition wall is extremely reduced. In addition to being easily and accurately specified, both the partition wall and the valve member have sufficient durability against wear and fatigue, so it is possible to set and maintain the vibration damping performance of the device as expected. it can.

(Example) Hereinafter, the present invention will be described based on illustrated examples.

FIG. 1 is a sectional view showing an embodiment of the present invention.
Reference numerals 11 and 12 denote a highly rigid inner cylinder and outer cylinder, respectively.

Here, these inner and outer cylinders 11 and 12 are connected to the outer peripheral surface with the intermediate cylinder 1
An elastic body 14 formed by joining 3 by vulcanization or the like is interconnected at both end portions in the axial direction, and a chamber 15 continuous in the circumferential direction is defined between the inner and outer cylinders in the central portion in the axial direction. Then, one fluid chamber 16 is formed by enclosing a liquid having a predetermined kinematic viscosity in the chamber.

Further, here, by fixing the partition wall 17 to the inner peripheral surface of the outer cylinder 12 at the center position in the axial direction thereof, the fluid chamber 16 is formed.
It is divided into two small chambers 16a, 16b which are separated from each other in the axial direction of the inner and outer cylinders. Here, the partition wall 17 in the illustrated example includes an annular outer peripheral rigid portion 17a fixed to the outer cylinder 12, an annular elastic portion 17b joined to an inner peripheral surface of the outer peripheral rigid portion 17a, and an annular elastic portion 17b. The outer peripheral rigid portion 17a and the slide ring 17c can be made of plastic, aluminum, iron or the like.

According to such a mounting structure of the partition wall 17, for example, the inner cylinder
When 11 vibrates with respect to the outer cylinder 12 in its axial direction, only the inner cylinder 11 vibrates under the deformation of the elastic body 14, but this partition wall 17 is attached to the inner cylinder 11. However, according to the former, when the inner cylinder 11 vibrates, the outer peripheral rigid portion 17a slides with respect to the outer cylinder 12. According to the latter, under the deformation of the annular elastic portion 17b, the partition wall 17
Will vibrate with the inner cylinder 11.

Further, here, in the four holes 17d formed in the outer peripheral rigid portion 17a of the partition wall 17 to bring the two small chambers 16a, 16b into communication,
A valve member 18, which is preferably made of a rigid material, is disposed so as to be slidable in the axial direction of the inner and outer cylinders, and stoppers 18 for limiting the sliding stroke are provided at both ends of each valve member 18.
Provide a respectively. Further, at least one of these valve members 18, that is, one valve member 18 in the figure, is provided with a throttle passage 19 which penetrates the valve member 18 and brings the two small chambers 16a and 16b into communication with each other. Here, the length of the throttle passage 19 can be appropriately selected by making it meander as shown in FIG.

When a plurality of fluid chambers that are separated in the circumferential direction are formed between the inner and outer cylinders, it is of course necessary to form a throttle passage in at least one of the valve members arranged in each fluid chamber. Is.

To manufacture such a vibration isolator, for example, first, at one end of the inner cylinder 11, an elastic body portion 14a is bonded to the outer peripheral surface of the inner cylinder 11 and the intermediate cylinder 13 by vulcanization or the like, and then the valve member 18 is preliminarily attached. The adhered partition wall 17 is fitted around the inner cylinder 11, and further, the elastic body portion 14c in which the ring 14b and the intermediate cylinder 13 are preliminarily adhered to the other end of the inner cylinder 11 is press-fitted in the liquid. Then, thereafter, the outer cylinder 12 can be caulked and fixed to the outer circumferences of the intermediate cylinder 13 and the partition wall 17 via an O-ring.

The absorption of the high-frequency small-amplitude vibrations in the vibration isolator is caused by the relative displacement of the inner and outer cylinders 11 and 12 in the axial direction.
The vibration of the partition wall 17 of FIG. 8 is sufficiently effective, and the damping of the low-frequency large-amplitude vibration is brought about by the flow of the liquid into the throttle passage 19 after the valve member 18 reaches the sliding limit position. .

FIG. 2 is a graph showing the result of such an action of the vibration isolator, and according to this graph, the dynamic spring constant shown by the solid line in the figure.
It is clear that Kd is significantly reduced due to the oscillatory movement of the valve member 18 in the frequency band higher than the frequency at which the throttle passage 19 is blocked by the liquid, and the loss factor tan δ of the device shown by the broken line in the figure. In other words, it is clear that the vibration damping performance is sufficiently high in the low frequency band.

In this case, in such an action of the vibration isolator, since the valve member 18 is disposed in the outer peripheral rigid portion 17a of the partition wall 17, the inner and outer cylinders 11 and 12 are arranged in a direction intersecting their axes. Due to the relative displacement to the inner ring 11, the slide ring 17c of the partition wall 17 can hinder the sliding motion of the valve member 18 even when the inner ring 11 is strongly pressed at any position in the circumferential direction. This is not the case at all, and as a result, the insulating function for high-frequency, small-amplitude vibrations is always fully exerted.
Further, in this vibration isolator, with respect to the outer peripheral rigid portion 17a,
This also preferably causes the valve member 18 made of a rigid material such as plastic, aluminum or iron to make a sliding motion, so that the sliding stroke of the valve member 18 can be specified easily and with sufficient accuracy. At the same time, it is possible to effectively prevent the dimensional change due to wear and fatigue of the outer peripheral rigid member 17a and the valve member 18, and therefore, the vibration damping performance of the device can be set as expected and maintained. can do.

FIG. 3 is a cross-sectional view showing another embodiment of the present invention. This example shows an outer peripheral groove 17e provided in the outer peripheral rigid portion 17a of the partition wall 17.
And the inner peripheral surface of the outer cylinder 12, each small chamber 16a, 16
One throttle passage 20 having an opening at b is formed. According to this example, since the length of the throttle passage 20 can be made sufficiently long, it is possible to further improve the vibration damping performance as compared with the example described above.

Further, in the example shown in FIG. 4, an annular elastic portion 17f is provided on the outer peripheral portion of the partition wall 17, a rigid portion 17g is joined to the inner peripheral surface of the annular elastic portion 17f, and the slide ring of each of the above-described embodiments is used. 17c is omitted, and this example also brings about the same effect as the device shown in FIG.

(Effect of the invention) Therefore, according to the present invention, even when the inner and outer cylinders are relatively displaced in the direction intersecting with their axes, the high-frequency small-amplitude vibration is sufficiently effective by the reliable vibration of the valve member. The vibration damping performance of the device can be set and maintained as expected because the sliding stroke of the valve member can be specified sufficiently accurately by the rigid part of the partition wall and the stopper of the valve member. can do.

Further, here, when the throttle passage is formed in any of the rigid portions of the device, it is possible to reliably prevent a change in damping performance due to the deformation.

[Brief description of drawings]

1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a graph showing the operation and effect of the apparatus shown in FIG. 1, and FIGS. 3 and 4 are sectional views showing other embodiments of the present invention. FIG. 5 is a sectional view showing a conventional example. 11 …… Inner cylinder, 12 …… Outer cylinder 14 …… Elastic body, 16 …… Fluid chamber 16a, 16b …… Small chamber, 17 …… Partition wall 17a …… Rigid peripheral part, 17b, 17f …… Round elastic part 17g ...... Rigid part, 18 ...... Valve member 18a ...... Stopper, 19,20 ...... Throttle passage

Claims (1)

[Claims] 1. A high-rigidity inner and outer cylinder, an elastic body interconnecting these inner and outer cylinders, and one or a plurality of fluid chambers formed between the inner and outer cylinders and filled with a liquid. Fixed to at least one of the cylinder and the outer cylinder, each of the fluid chambers,
In a vibration isolator comprising a partition wall that is divided into two small chambers that are separated from each other in the axial direction of the inner and outer cylinders, and at least one throttle passage that provides communication between these two small chambers, an annular elastic portion is provided on the partition wall. And a rigid portion that is inscribed or circumscribed in the annular elastic portion, and a valve member that is slidable over a predetermined amount in the axial direction of the inner and outer cylinders is disposed in the rigid portion.