JPH07127684A - Fluid-seal type bushing - Google Patents

Abstract

PURPOSE:To provide a fluid-seal bearing which can effectively exhibit a vibration damping effect based upon resonant action of fluid over a wide frequency range of input vibration. CONSTITUTION:In a fluid-seal type bushing in which pair of fluid chambers 42, 42 which are communicated together through an orifice passage 28 are provided between inner and outer cylindrical members 12, 14, constrictions 44, 46 are formed in predetermined circumferential parts of the chambers 42, 44, a thin membrane part having a shear spring constant of less than 1kgf/mm is formed in each of partition wall parts 38, 38 which partition the fluid chambers 42, 42, and accordingly, the deformation-proof rigidity in a direction, in which the partition wall part 38 bulges out is set to be substantially less than that of side wall parts on opposite sides of the axis of the fluid chambers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid-filled bush suitable for use in an automobile suspension bush, an engine mount, or the like, which has a vibration-damping effect based on the flow of a fluid filled inside.

[0002]

2. Description of the Related Art Conventionally, an inner tubular metal fitting and an outer tubular metal fitting arranged radially outward of the outer tubular metal fitting are elastically connected by a rubber elastic body interposed therebetween. , As a kind of vibration-proof bush mainly adapted to prevent the radial input vibration between the inner and outer cylindrical metal fittings.
As disclosed in Japanese Patent Application Laid-Open No. 2-16554 and Japanese Patent Application Laid-Open No. 56-164242, a pair of fluid chambers facing each other in the main vibration input direction are formed between the inner tubular metal fitting and the outer tubular metal fitting. A fluid-filled bush having an orifice passage that communicates the pair of fluid chambers with each other is known. In such a fluid-filled type bush, when vibration is input, a predetermined vibration damping effect is exhibited based on the resonance action of the fluid that is made to flow between the fluid chambers through the orifice passage.

By the way, in the case where the type and frequency of input vibrations are changed under various conditions, or a plurality of types of input vibrations are input, such as a suspension bush for an automobile, a low frequency region to a high frequency region are inputted. A stable anti-vibration effect is required for input vibration in a wide frequency range over a range.

However, the conventional fluid-filled bush has a narrow frequency range in which the vibration-damping effect based on the resonance action of the fluid that is made to flow through the orifice passage can be effectively exhibited. It was extremely difficult to obtain an effective anti-vibration effect. For example, in the suspension bushing, if the orifice passage is tuned so that effective vibration damping effect against low frequency vibration such as shimmy is exhibited, the orifice passage will be substantially closed at the time of vibration input in the middle to high frequency range. Therefore, there is a problem that the anti-vibration performance against road noise and the like is significantly deteriorated due to the high dynamic spring.

[0005]

The present invention has been made in view of the above circumstances, and a problem to be solved by the present invention is that a vibration isolation effect based on the flow of a fluid has an input vibration in a wide frequency range. It is an object of the present invention to provide a fluid-filled bush that can be advantageously exhibited.

[0006]

In order to solve such a problem, a feature of the present invention resides in that an inner cylindrical metal member and an outer cylindrical metal member, which are arranged at a predetermined distance in a radial direction from each other, are connected by a rubber elastic body. On the other hand, between the inner tubular metal member and the outer tubular metal member, a pair of fluid chambers facing each other in one radial direction are formed,
In a fluid-filled bush provided with an orifice passage that connects the pair of fluid chambers to each other, a narrowed portion that projects from the inner tubular metal fitting side toward the outer tubular metal fitting side and is located at a predetermined circumferential portion of the fluid chamber. And a thin film portion having a shear spring constant of 1 kgf / mm or less is provided on the partition wall portion of the rubber elastic body that partitions the pair of fluid chambers on both sides of the inner tubular metal fitting. The deformation rigidity of the partition wall in the bulging direction is substantially smaller than that of the side wall portions on both axial sides of the fluid chamber.

[0007]

EXAMPLES Examples of the present invention will now be described in detail with reference to the drawings in order to clarify the present invention more specifically.

First, FIGS. 1 and 2 show an automobile suspension bush 10 as an embodiment of the present invention. The suspension bush 10 has a structure in which an inner tubular metal member 12 and an outer tubular metal member 14 are connected by a rubber elastic body 16 interposed therebetween, and the inner tubular metal member 12 has a suspension arm (not shown). On the other hand, the outer cylinder metal fitting 14 is attached to a frame (not shown) so as to be interposed at the attachment portion of the suspension arm to the frame. Then, in the mounted state, the main vibration to be isolated from the vibration is input between the inner and outer cylindrical metal fittings 12 and 14 in the suspension bush 10 in one radial direction corresponding to the vertical direction in FIG. .

More specifically, the inner tubular member 12 has a thick-walled cylindrical shape. Further, a protruding metal member 18 as a protruding member is attached to a central portion of the inner cylindrical metal member 12 in the axial direction. The protruding metal fitting 18 has a substantially rectangular block shape, and has a mounting hole 2 formed at the center thereof.
At 0, it is externally fitted and fixed to the inner tubular member 12. Then, by the protruding metal fitting 18, a pair of protruding portions 22, 2 protruding at a predetermined height toward both sides in the radial direction of the inner tubular metal fitting 12.
2 are formed.

Further, in the protruding metal member 18, a concave groove 24 continuously extending in the circumferential direction on the inner peripheral surface of the mounting hole 20 and each protruding portion 2 are provided.
2 extends through the inside in a protruding direction, and both end portions are recessed grooves 24.
And a pair of communication holes 26, 26 opened at the tip end surface of the protrusion 22. And the protruding metal fitting 1
In the state of being attached to the inner tubular metal fitting 12 of 8, the concave groove 24 is covered by the inner tubular metal fitting 12, so that the outer peripheral surface of the inner tubular metal fitting 12 is covered by the concave groove 24 and the pair of communication holes 26, 26. An orifice passage 28 is formed that extends in the circumferential direction and opens at the tip surfaces of both protrusions 22, 22. In the present embodiment, based on the resonance action of the fluid that is made to flow through the inside of the orifice passage 28, a low dynamic spring effect can be exerted at the time of vibration input in the low frequency range.
The length and cross-sectional area of the orifice passage 28 are tuned.

Furthermore, a thin-walled cylindrical metal sleeve 3 is provided outwardly in the radial direction of the inner tubular member 12 at a predetermined distance.
0 is arranged substantially coaxially. A pair of opening windows 32, 32 extending in the circumferential direction with a length of a little less than half the circumference are formed in the axially central portion of the metal sleeve 30 at positions facing each other in the radial direction. Further, the metal sleeve 30 is circumferentially positioned with respect to the inner tubular metal member 12 so that the opening windows 32, 32 are located outside the projecting portions 22, 22, respectively.

A rubber elastic body 16 is interposed between the inner tubular member 12 and the metal sleeve 30. The rubber elastic body 16 has a substantially thick-walled cylindrical shape as a whole, and the inner tubular metal member 12 is vulcanized and adhered to the inner cylindrical metal member 12 and the metal sleeve 30 to the outer peripheral surface thereof. Is formed as. If necessary, preliminary compression is applied to the integrally vulcanized product by subjecting the metal sleeve 30 to octagonal drawing.

The integral vulcanization molded product has a pair of pockets 34, 34 formed on opposite sides of the inner tubular member 12 with the inner tube 12 sandwiched in the projecting direction of the projecting portions 22, 22. The outer peripheral surface is opened through the opening window 32 of the metal sleeve 30. It should be noted that the projections 22 are located in the respective pockets 34, and are projected at a predetermined height from the center of the bottom toward the opening. In addition, a cushioning rubber layer 36 having a predetermined thickness is provided on the tip end surface of each of the protrusions 22,
It is formed by the rubber elastic body 16.

Further, in the rubber elastic body 16, the partition wall portion 38 is located between the bottom portions of the pocket portions 34, 34 on both sides of the inner tubular metal fitting 12 so as to partition the pocket portions 34, 34 from each other. , 38 are thinned almost all over. That is, in this embodiment, the partition wall portion 38
The whole of is composed of the thin film portion.
In the following description of the present embodiment, the reference numeral (38) of the partition wall portion will also be used as the reference numeral of the thin film portion.

The thin film portion 38 has a shear spring constant set to 1 kgf / mm or less, and the partition wall portion 3
The deformation rigidity of the entire 8 in the bulging direction is set sufficiently smaller than the deformation rigidity of the side wall portions 39 on both axial sides of the pocket portion 34 in the bulging direction. As a result, the thin film portion 38 can be easily bulged and deformed in the facing direction of the pocket portions 34, 34 on the basis of the pressure difference exerted on the both surfaces thereof, and the thin film portion 38 has a large surface area. When the pressure difference is exerted, the elastic force exerts a deformation resistance force so that the amount of bulging deformation can be regulated.

Further, an outer cylinder metal fitting 14 is externally fitted to such an integrally vulcanized molded product, and is fitted and fixed to the outer peripheral surface of the metal sleeve 30 by an eight-way drawing process or the like. In addition, a thin seal rubber layer 40 is provided and vulcanized and adhered to the inner peripheral surface of the outer tubular metal member 14 over substantially the entire surface thereof, and a space between the fitting surfaces of the metal sleeve 30 and the outer tubular metal member 14 is provided. It is pinched by and is sealed fluid-tight between them.

The outer tubular metal fitting 14 allows the opening windows 32, 32 of the metal sleeve 30, that is, the pocket portion 3.
The openings of the fluid chambers 4 and 34 are covered in a fluid-tight manner, so that a pair of fluid chambers 4 each containing a predetermined incompressible fluid are enclosed.
2, 42 are formed. As the enclosed fluid, in order to advantageously obtain the vibration damping effect based on the resonance action of the fluid, for example, a low-viscosity fluid made of water, alkylene glycol, polyalkylene glycol, silicone oil, or a mixture thereof, It is preferably adopted. Also,
The operation of enclosing the fluid is performed by, for example, assembling the outer tubular metal fitting 14 with respect to the integrally vulcanized molded article in the fluid.
It can be done to your advantage.

That is, these fluid chambers 42, 42 are
Each of the inner and outer cylindrical metal fittings 12 and 14 extends in the circumferential direction by a length of about half a circumference, and is positioned so as to face each other in the main vibration input direction with the thin film portions 38 and 38 interposed therebetween. It is in communication with.

Further, the inside of these fluid chambers 42, 42 is narrowed in the radial direction and the axial direction by the protruding metal fitting 18. Then, in particular, in the facing portions on both sides in the circumferential direction of the fluid chambers 42, 42, respectively, across the both sides sandwiching the thin film portion 38, between the radially facing surfaces of the protruding metal fitting 18 and the metal sleeve 30. A first narrowed portion 44 is formed.
Furthermore, in the present embodiment, also in the circumferential center part of each fluid chamber 42, the space between the radially facing surfaces of the protruding portion 22 of the protruding metal member 18 and the outer cylindrical metal member 14 is narrowed, and Narrowed portion 46 is formed. In the present embodiment, the first and second narrowed portions 44 and 46 are both low motion springs at the time of vibration input in the middle to high frequency range based on the resonance action of the fluid that is made to flow therethrough. The length, cross-sectional area, etc. are tuned so that the effect can be exhibited.

Furthermore, in this embodiment, the tip surfaces of the protruding portions 22, 22 of the protruding metal fitting 18 are positioned so as to oppose the outer cylindrical metal fitting 14 with a predetermined distance in the main vibration input direction, so that a large vibration occurs. When a load is input, the protruding portions 22, 2
The tip end surface of 2 is brought into contact with the inner peripheral surface of the outer tubular metal fitting 14, whereby the relative displacement amount of the inner and outer tubular metal fittings 12 and 14 is regulated. That is, in this embodiment, the protruding portions 22, 22 of the protruding metal member 18 also have a stopper function.

The suspension bush 10 having the above-mentioned structure is, for example, as described above, the inner tubular fitting 12 thereof.
While the pivot fixed to the suspension arm (not shown) is inserted and fixed, the outer cylinder metal fitting 14 is press-fitted and fixed in the mounting hole of the frame (not shown), so that the suspension arm is interposed in the attachment portion to the frame. Therefore, in the mounted state, the main vibration to be isolated is input between the inner and outer cylindrical metal fittings 12 and 14 in the vertical direction in FIG.

At the time of vibration input, the inner tubular metal fitting 12 and the outer tubular metal fitting 14 are displaced (vibrated) in the radial direction (vertical direction in FIG. 1) with respect to each other, and as a result, both fluid chambers 42, 42. In the meantime, a relative change in internal pressure is forcibly produced.

If the input vibration is large-amplitude vibration in the low frequency range such as shimmy, the inner and outer cylindrical metal fittings 1
2 and 14 have large relative displacements, and both fluid chambers 42 and 4
Since a large internal pressure difference occurs between the two fluid chambers, a fluid flow through the orifice passage 28 is induced between the fluid chambers 42, 42 based on the internal pressure difference. Then, based on the resonance action of the fluid that is made to flow through the orifice passage 28, the low dynamic spring effect is exhibited, and the reduction of the vibration transmission force can be achieved.

When a low-frequency large-amplitude vibration is input, the internal pressure difference generated between the fluid chambers 42, 42 is large,
Since the amount of bulging deformation of the thin film portions 38, 38 is limited by its elastic force, absorption of the internal pressure difference due to the bulging deformation of the thin film portions 38, 38 is avoided, and the amount of fluid flow through the orifice passage 28 is reduced. Sufficiently secured and effective vibration damping effect can be exhibited.

On the other hand, when the input vibration is small-amplitude vibration in the middle to high frequency range such as road noise, the relative displacement amount of the inner and outer cylindrical metal fittings 12 and 14 is small, and both fluid chambers 42 and
Since the internal pressure difference between 42 is small, the thin film portion 38,
Due to the bulging deformation of 38, a relative volume change is caused between the fluid chambers 42, 42. That is, the thin film portions 38, 38 have a shear spring constant set to 1 kgf / mm or less so that a small bulging deformation can be allowed very easily. Therefore, a small internal pressure between the fluid chambers 42, 42 is generated. When a difference is created, the thin film portions 38, 38
By bulging and deforming from the side of the fluid chamber 42 whose internal pressure has risen to the side of the other fluid chamber 42, it is possible to substantially allow the circumferential flow of fluid between the two fluid chambers 42, 42.

Therefore, when a small amplitude vibration in the middle to high frequency range is input, the two fluid chambers 42, 42 function as if they were one continuous annular fluid chamber in the circumferential direction, and both fluid chambers 4
A continuous fluid flow in the circumferential direction is generated between the two and 42. In other words, when a small amplitude vibration in the middle to high frequency range is input, the thin film portions 38, 38 substantially lose the function as a partition that partitions the fluid chambers 42, 42,
Based on the bulging deformation, the fluid flow between the fluid chambers 42, 42 can be allowed.

Moreover, the partition walls 38, 38 partitioning the fluid chambers 42, 42 have a deformation rigidity in the bulging direction smaller than that of the side wall portions 39, 39, and the partition walls 38, 38 within the fluid chamber 42 Since the absorption due to the bulging deformation of the side wall portion 39 is prevented, based on the internal pressure difference between the fluid chambers 42, 42,
The circumferential fluid flow due to the bulging deformation of the partition walls 38, 38 can be generated very efficiently.

As described above, as a result of the flow of the fluid which is substantially continuous in the circumferential direction between the fluid chambers 42, 42, the fluid passing through the first narrowed portion 44 and the second narrowed portion 46. Is advantageously generated, so that a low dynamic spring effect is exerted based on the resonance action of the fluid that is caused to flow through the first and second narrowed portions 44 and 46, and the vibration transmission force is reduced. Mitigation can be achieved.

Incidentally, the results of measuring the vibration damping characteristics of the suspension bush 10 of the structure of this embodiment are shown in FIG.
Shown in. In addition, in the figure, the results of similar measurements are also shown as a comparative example for a suspension bush having a conventional structure in which the partition walls 38, 38 are not provided with a thin film portion.

From the measurement results shown in FIG. 3, the suspension bush 10 of this embodiment has the following structure.
In addition to having an excellent anti-vibration effect against low frequency vibration of about 20 to 30 Hz which corresponds to shimmy etc., it also has a good anti-vibration effect against medium to high frequency vibration of about 200 to 300 Hz which corresponds to road noise etc. it is obvious.

Next, FIGS. 4 and 5 show a suspension bush 50 as another embodiment of the present invention. In the present embodiment, members and parts having the same structure as the first embodiment are designated by the same reference numerals as those in the first embodiment in the drawings, and detailed description thereof will be omitted. .

That is, in the suspension bush 50 of the present embodiment, the central portion of the thin film portion 38 is thickened and the mass portion 52 is integrally formed. Even if the mass portion 52 is formed, the peripheral portion of the thin film portion 38 is thinned so that the thin film portion as a whole can exhibit a shear spring constant of 1 kgf / mm or less.

Therefore, in the suspension bush 50 having such a structure, in addition to the effects similar to those of the first embodiment being effectively exhibited, the mass portion 52 provided in the thin film portion 38 is also provided. It is possible to utilize the resonance effect of the thin film portion 38 by appropriately tuning the mass and the like of the thin film portion 38, thereby more efficiently producing the fluid flow in the first and second narrowed portions 44 and 46. Therefore, it is possible to obtain a more effective anti-vibration effect against the input vibration in the middle to high frequency range.

Although the embodiments of the present invention have been described above in detail, these are literal examples and the present invention should not be construed as being limited to such embodiments.

For example, in the above embodiment, the fluid chamber 4
Although the partition wall portion 38 for partitioning the partition walls 2, 42 is formed as a thin film portion over substantially the entire surface, one or two or more thin film portions may be partially provided with respect to the partition wall portion 38.

It is also effective to set the shear spring constant of the thin film portion to 0 or a value close to it by forming the thin film portion with a thin curved plate shape as a whole.

Further, in the above embodiment, the orifice passage exerts a low dynamic spring effect at the time of vibration input in the low frequency range corresponding to shimmy, while the first and second narrowed portions 44 and 46 cause road noise. It was tuned so that a low dynamic spring effect was exhibited at the time of vibration input in the middle to high frequency range corresponding to the above, but the tuning of these orifice passages and narrowed parts depends on the vibration damping characteristics required for the bush. It should be changed and set appropriately, and is not limited. For example, the orifice passage provides a high damping effect at the time of vibration input in the low frequency range of about 10 Hz, and the narrowed portion causes 100 Hz.
It is, of course, possible to tune the orifice passages and the narrowed portions so that the low dynamic spring effect is exerted when the vibrations in the front and rear middle to high frequency regions are input.

It is also possible to integrally form the protruding member forming the narrowed portion in the fluid chamber with a rubber elastic body. Moreover, the protruding member does not necessarily have to have a stopper function.

Furthermore, the narrowed portion may be formed at least at one location on the circumference of both fluid chambers, and the formation portion is not limited to the above embodiment.

Further, in the above embodiment, the orifice passage is formed along the outer peripheral surface of the inner cylindrical metal member, but the formation position and structure of the orifice passage are not limited, and the inner peripheral surface of the outer cylindrical metal member is not limited. It is also possible to form along the barrier ribs or to form the partition wall portion.

In addition, in the above-mentioned embodiment, a specific example of the present invention applied to a suspension bush for an automobile has been shown. Any of these bushes can be applied to advantage.

Although not listed one by one, the present invention is
Based on the knowledge of those skilled in the art, it can be implemented in various modified, modified, and improved modes, and
It goes without saying that all such embodiments are included in the scope of the present invention without departing from the spirit of the present invention.

[0043]

As is apparent from the above description, in the fluid-filled type bush having the structure according to the present invention, when the low frequency large amplitude vibration is inputted, the protection based on the resonance action of the fluid caused to flow through the orifice passage is prevented. While the vibration effect is effectively exhibited, when a small-amplitude vibration in the middle to high frequency range is input, a continuous circumferential fluid flow is generated between both fluid chambers due to the bulging deformation of the thin film portion. As a result, the vibration damping effect based on the resonance action of the fluid that is caused to flow through the narrowed portion can be effectively exhibited.

Therefore, in such a fluid-filled type bush, an effective vibration-damping effect can be exerted against the input vibration in a wide frequency range by the resonance action of the fluid caused to flow through the orifice passage and the narrowed portion.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a suspension bush as an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a graph showing the measurement results of the vibration damping characteristics of the suspension bush having the structure shown in FIG. 1 together with a comparative example.

FIG. 4 is a cross sectional view showing a suspension bush as another embodiment of the present invention.

5 is a sectional view taken along line VV in FIG.

[Explanation of symbols]

 10, 50 Suspension bush 12 Inner cylinder fitting 14 Outer cylinder fitting 16 Rubber elastic body 18 Projection fitting 28 Orifice passage 38 Partition wall (thin film part) 39 Side wall part 42 Fluid chamber 44 First narrowing part 46 Second narrowing part

Claims (1)

[Claims] 1. An inner tubular metal member and an outer tubular metal member, which are arranged at a predetermined distance in a radial direction from each other, are connected by a rubber elastic body,
A fluid-filled bush in which a pair of fluid chambers that are opposed to each other in a radial direction are formed between the inner tubular metal member and the outer tubular metal member, and an orifice passage that connects the pair of fluid chambers to each other is provided. , Protruding from the inner tubular metal fitting side toward the outer tubular metal fitting side,
A protruding member that forms a narrowed portion is provided at a predetermined position in the circumferential direction of the fluid chamber, and a shearing force of 1 kgf / mm or less is applied to the partition wall portion of the rubber elastic body that partitions the pair of fluid chambers on both sides of the inner tubular metal fitting. A fluid-filled bush characterized in that each thin film portion having a spring constant is provided, and the deformation rigidity of the partition wall portion in the bulging direction is made substantially smaller than that of side wall portions on both axial sides of the fluid chamber. .