JP2827846B2 - Fluid-filled bush - Google Patents

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, and the like, which obtains an anti-vibration effect based on the flow of a fluid sealed therein.

[0002]

2. Description of the Related Art Conventionally, an inner cylindrical member and an outer cylindrical member arranged radially outward at a predetermined distance are elastically connected by a rubber elastic body interposed therebetween. As a kind of vibration-isolating bush that is mainly designed to dampen radial input vibration between the inner and outer cylindrical fittings,
As disclosed in JP-A-2-16554 and JP-A-56-164242, a pair of fluid chambers facing each other in the main vibration input direction are formed between an inner cylinder and an outer cylinder. 2. Description of the Related Art A fluid-filled bush provided with an orifice passage that connects the pair of fluid chambers to each other is known. In such a fluid-filled bush, at the time of vibration input, a predetermined vibration-proof effect is exerted based on the resonance action of the fluid that flows between the fluid chambers through the orifice passage.

In the case where the type and frequency of input vibrations change according to various conditions, such as a suspension bush for an automobile, and when a plurality of types of input vibrations are input, the frequency range from a low frequency range to a high frequency range is reduced. A stable anti-vibration effect is required for input vibration in a wide frequency range over a wide range.

[0004] However, in the conventional fluid-filled bush, the frequency range in which the vibration damping effect based on the resonance action of the fluid caused to flow through the orifice passage can be effectively exerted is narrow, so that the input vibration in a wide frequency range is suppressed. It was extremely difficult to obtain an effective vibration damping effect. For example, in the suspension bush, when the orifice passage is tuned so as to exhibit an effective vibration damping effect against low-frequency vibrations such as shimmy, the orifice passage is substantially closed when vibrations in a middle to high frequency range are input. As a result, there is a problem that the vibration isolating performance against road noise and the like is greatly reduced due to the high dynamic spring.

[0005]

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a vibration damping effect based on the flow of a fluid that can be applied to input vibrations in a wide frequency range. An object of the present invention is to provide a fluid-filled bush that can be advantageously used for

[0006]

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

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

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

More specifically, the inner cylindrical fitting 12 has a thick cylindrical shape. A protruding fitting 18 as a protruding member is attached to a central portion in the axial direction of the inner cylindrical fitting 12. The protruding metal fitting 18 has a substantially rectangular block shape, and has a mounting hole 2 penetrating through a central portion thereof.
At 0, it is externally fitted and fixed to the inner tube fitting 12. A pair of protruding portions 22 and 2 projecting at predetermined heights toward both sides in the radial direction of the inner cylindrical metal member 12 by the protruding metal members 18.
2 are formed.

The protruding metal fitting 18 has a concave groove 24 extending continuously in the circumferential direction on the inner peripheral surface of the mounting hole 20.
2 extend in the protruding direction through the interior of
A pair of communication holes 26, 26 opened in the front end surface of the projection 22 are formed. And the protruding metal fitting 1
8, the concave groove 24 is covered with the inner cylindrical metal fitting 12, and the outer peripheral surface of the inner cylindrical metal fitting 12 is formed by the concave groove 24 and the pair of communication holes 26, 26. Orifice passages 28 that extend in the circumferential direction and that open at the tip surfaces of both protruding portions 22 are formed. In the present embodiment, based on the resonance action of the fluid caused 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 a low frequency range.
The length and cross-sectional area of the orifice passage 28 are tuned.

Further, a thin cylindrical metal sleeve 3 is provided radially outward of the inner cylindrical fitting 12 at a predetermined distance.
0 are arranged substantially coaxially. A pair of opening windows 32, 32 extending in the circumferential direction with a length of less than half a circumference, respectively, are formed in a central portion in the axial direction of the metal sleeve 30 at portions opposed to each other in one radial direction. Further, the metal sleeve 30 is positioned in the circumferential direction with respect to the inner cylindrical metal fitting 12 so that the opening windows 32, 32 are positioned outside the protruding portions 22, 22, respectively.

A rubber elastic body 16 is interposed between the inner metal fitting 12 and the metal sleeve 30. The rubber elastic body 16 has a substantially thick cylindrical shape as a whole, and is formed by integrally vulcanizing the inner cylindrical fitting 12 on the inner peripheral surface and the metal sleeve 30 on the outer peripheral surface. It is formed as. The integrally vulcanized molded product is pre-compressed by subjecting the metal sleeve 30 to, for example, eight-way drawing.

The integrally vulcanized molded product is formed with a pair of pocket portions 34, 34 on both sides of the inner cylindrical fitting 12 opposed to each other with the protruding portions 22, 22 interposed therebetween. , Through the opening window 32 of the metal sleeve 30. In each of the pocket portions 34, a protruding portion 22 is positioned, and protrudes at a predetermined height from the center of the bottom toward the opening. In addition, a cushion rubber layer 36 having a predetermined thickness is provided on the distal end surface of the protruding portion 22, respectively.
It is formed by a rubber elastic body 16.

Further, the rubber elastic body 16 is located between the bottoms of the pockets 34, 34 on both sides of the inner cylindrical fitting 12 so as to partition between the pockets 34, 34. , 38 are thinned over substantially the entirety. That is, in the present embodiment, the partition 38
Is formed by the thin film portion.
In the following description of the present embodiment, the reference numeral (38) of the partition wall portion is also 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 portion 3
The deformation rigidity in the bulging direction of the whole 8 is set sufficiently smaller than the deformation rigidity in the bulging direction of the side wall portions 39 on both axial sides of the pocket portion 34. Thus, the thin film portion 38 can be easily swelled and deformed in the direction in which the two pocket portions 34 and 34 face each other based on the pressure difference exerted on both surfaces thereof, and a large amount is formed on both surfaces. When a pressure difference is applied, a deformation resistance force acts by the elastic force, so that the swelling deformation amount can be regulated.

Further, an outer tube fitting 14 is externally inserted into 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. A thin seal rubber layer 40 is provided on almost the entire inner peripheral surface of the outer cylinder fitting 14 and is vulcanized and bonded, so that the metal sleeve 30 and the outer cylinder fitting 14 can be fitted together. And a fluid tight seal is provided between them.

The outer metal fittings 14 allow the windows 32, 32 of the metal sleeve 30, that is, the pockets 3 to be opened.
4 and 34 are fluid-tightly covered, so that a pair of fluid chambers 4 each of which is filled with a predetermined incompressible fluid.
2, 42 are formed. In order to advantageously obtain a vibration damping effect based on the resonance action of the fluid, for example, a low-viscosity fluid composed of water, an alkylene glycol, a polyalkylene glycol, a silicone oil, or a mixture thereof is used as the sealed fluid. It is preferably adopted. Also,
The operation of enclosing the fluid is performed, for example, by assembling the outer cylinder fitting 14 to the integrally vulcanized molded product in the fluid, or the like.
It can be done advantageously.

That is, these fluid chambers 42, 42
Each of the inner and outer cylindrical fittings 12 and 14 extends in the circumferential direction by a length of substantially half a circumference, and is opposed to each other in the main vibration input direction with the thin film portions 38 and 38 interposed therebetween. It is communicated to.

The interior of the fluid chambers 42, 42 is constricted in the radial and axial directions by the protruding metal fittings 18. In particular, the opposing parts on both sides in the circumferential direction of the two fluid chambers 42, astride both sides sandwiching the thin film part 38, respectively, between the radially opposing surfaces of the protruding fitting 18 and the metal sleeve 30. A first constriction 44 is formed.
Furthermore, in the present embodiment, even at the circumferential center portion of each fluid chamber 42, the space between the distal end surface of the protruding portion 22 of the protruding metal fitting 18 and the radially opposed surface between the outer cylindrical metal fitting 14 is narrowed, and the second Is formed. In the present embodiment, both the first and second constricted portions 44 and 46 are provided with a low dynamic spring when a vibration in a middle to high frequency range is input, based on the resonance action of the fluid flowing through the inside. The length, cross-sectional area, etc. are tuned so that the effect can be exhibited.

Further, in the present embodiment, the distal end surfaces of the protruding portions 22, 22 of the protruding metal fitting 18 are opposed to the outer cylindrical metal fitting 14 at a predetermined distance in the main vibration input direction, so that a large vibration is generated. When a load is input, the protrusions 22 and 2
The distal end surface of the inner cylinder 2 is brought into contact with the inner peripheral surface of the outer cylinder 14 so that the relative displacement of the inner and outer cylinders 12 and 14 is regulated. That is, in this embodiment, the protruding portions 22, 22 of the protruding fitting 18 also have a stopper function.

The suspension bush 10 structured as described above is, for example, as described above,
In addition, the pivot attached to the suspension arm (not shown) is inserted and fixed, and the outer cylinder fitting 14 is press-fitted and fixed to the mounting hole of the frame (not shown), so that the suspension arm is interposed at the mounting portion to the frame. That is, in the mounted state, the main vibration to be damped is input between the inner and outer tube fittings 12 and 14 in the vertical direction in FIG.

At the time of vibration input, the inner cylinder fitting 12 and the outer cylinder fitting 14 are displaced (vibrated) in the radial direction (vertical direction in FIG. 1), and as a result, both fluid chambers 42, 42 are provided. A relative change in internal pressure is forced between them.

If the input vibration is a large-amplitude vibration in a low frequency range such as shimmy, the inner and outer cylinder fittings 1
The relative displacement between the fluid chambers 42 and 4 is large.
Since a large internal pressure difference is generated between the two, the flow of the fluid through the orifice passage 28 is caused between the two fluid chambers 42, 42 based on the internal pressure difference. Then, based on the resonance action of the fluid caused to flow through the orifice passage 28, a 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 two fluid chambers 42 is large.
Since the amount of swelling deformation of the thin film portions 38, 38 is limited by the elastic force, absorption of the internal pressure difference due to swelling 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, an effective anti-vibration effect can be exhibited.

On the other hand, when the input vibration is a small-amplitude vibration in a medium to high frequency range such as road noise, the relative displacement of the inner and outer cylindrical fittings 12 and 14 is small, and the two fluid chambers 42 and
Since the internal pressure difference generated between the thin film portions 38 and 42 is small,
A relative volume change is caused between the two fluid chambers 42, 42 based on the bulging deformation of 38. That is, since the thin film portions 38, 38 have a shear spring constant set to 1 kgf / mm or less, and small swelling deformation can be extremely easily tolerated, a small internal pressure between the two fluid chambers 42, 42 is provided. When a difference is created, such thin film portions 38, 38
By being swelled and deformed from the fluid chamber 42 side where the internal pressure has increased to the other fluid chamber 42 side, the flow of the fluid in the circumferential direction between the two fluid chambers 42 and 42 can be substantially allowed.

Therefore, when a small-amplitude vibration in the middle to high frequency range is input, the two fluid chambers 42, 42 function as an annular fluid chamber that is continuous in the circumferential direction.
A continuous fluid flow in the circumferential direction is generated between the portions 2 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 their function as partitions separating the fluid chambers 42, 42,
Based on the bulging deformation, the flow of the fluid between the two fluid chambers 42, 42 can be allowed.

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

As described above, a substantially continuous fluid flow is generated between the fluid chambers 42 and 42 in the circumferential direction. As a result, the fluid flowing through the first constricted portion 44 and the second constricted portion 46 is formed. Is advantageously generated, and a low dynamic spring effect is exerted on the basis of the resonance action of the fluid caused to flow through the first and second constrictions 44 and 46, and the vibration transmission force is reduced. Mitigation can be achieved.

FIG. 3 shows the results of measuring the vibration isolation characteristics of the suspension bush 10 having the structure of the embodiment.
Shown in In this figure, the results of similar measurements performed on a suspension bush having a conventional structure in which no thin film portion is provided on the partition walls 38, 38 are also shown as comparative examples.

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 corresponding to shimmy, etc., it also has a good anti-vibration effect against medium to high frequency vibration of about 200 to 300 Hz corresponding to road noise and the like. 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 in the first embodiment are denoted by the same reference numerals in the drawings as in the first embodiment, and detailed description thereof is omitted. .

That is, in the suspension bush 50 of this embodiment, the central portion of the thin film portion 38 is thickened, and the mass portion 52 is formed integrally. Even when the mass portion 52 is formed, the peripheral portion of the thin film portion 38 is thinned, so that the entire thin film portion 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, any of the mass portions 52 provided in the thin film portion 38 can be effectively provided. By appropriately tuning the mass or the like, the resonance effect of the thin film portion 38 can be used, whereby the fluid flow in the first and second constricted portions 44 and 46 can be more efficiently generated. Thus, a more effective vibration damping effect can be obtained with respect to input vibrations in a 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 is not construed as being limited to only such embodiments.

For example, in the above embodiment, the fluid chamber 4
Although the partition wall section 38 that partitions the partition walls 2 and 42 is formed as a thin film section over substantially the entire surface, one or two or more thin film sections may be provided in the partition wall section 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 in a thin curved plate shape as a whole.

Further, in the above-described embodiment, the orifice passage exerts a low dynamic spring effect at the time of vibration input in a low frequency range corresponding to shimmy, while the first and second constricted portions 44 and 46 cause road noise. The orifice passages and constrictions were tuned so that a low dynamic spring effect was exhibited at the time of vibration input in a medium to high frequency range corresponding to the following. It should be changed and set as appropriate, and is not limited. For example, the orifice passage allows a high damping effect to be exerted at the time of vibration input in a low frequency range of about 10 Hz.
Of course, it is also possible to tune these orifice passages and constrictions so that a low dynamic spring effect is exerted at the time of vibration input in the middle or high frequency range before and after.

Further, the protruding member forming the constricted portion in the fluid chamber may be integrally formed by a rubber elastic body. Further, the projecting member does not necessarily need to have a stopper function.

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

In the above-described embodiment, the orifice passage is formed along the outer peripheral surface of the inner cylindrical member. However, the position and structure of the orifice passage are not limited, and the inner peripheral surface of the outer cylindrical member is not limited. Or along the partition wall.

In addition, in the above-described embodiment, a specific example in which the present invention is applied to a suspension bush for an automobile has been described. However, the present invention is not limited to this and may be applied to an engine mount, a differential mount, a body mount, or various types other than an automobile. Any of the above can be advantageously applied to the bush.

In addition, although not enumerated one by one, the present invention
Based on the knowledge of those skilled in the art, the present invention can be implemented in a form in which various changes, modifications, improvements, and the like are made.
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 clear from the above description, in the fluid-filled bush having the structure according to the present invention, when a low-frequency, large-amplitude vibration is input, the prevention based on the resonance action of the fluid caused to flow through the orifice passage. 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 the two fluid chambers based on the bulging deformation of the thin film portion. Thereby, the vibration damping effect based on the resonance action of the fluid caused to flow through the constriction can be effectively exhibited.

Therefore, in such a fluid-filled bush, an effective vibration damping effect against input vibrations in a wide frequency range can be exhibited by the resonance action of the fluid flowing through the orifice passage and the constricted portion.

[Brief description of the drawings]

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

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

FIG. 3 is a graph showing measurement results of vibration isolation characteristics of a 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.

FIG. 5 is a sectional view taken along line VV in FIG. 4;

[Explanation of symbols]

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

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-193431 (JP, A) JP-A-1-116330 (JP, A) JP-A-1-126452 (JP, A) JP-A-56- 16242 (JP, A) JP-A-3-194237 (JP, A) JP-A-59-164428 (JP, A) JP-A-1-234635 (JP, A) JP-B-52-16554 (JP, B2) (58) Field surveyed (Int. Cl. ⁶ , DB name) F16F 13/00

Claims (1)

(57) [Claims] An inner cylinder and an outer cylinder, which are arranged at a predetermined distance from each other in a radial direction, are connected by a rubber elastic body.
In a fluid-filled bush, a pair of fluid chambers facing each other in one radial direction are formed between the inner cylinder and the outer cylinder, and an orifice passage communicating the pair of fluid chambers is provided. Protruding from the inner cylinder side toward the outer cylinder side;
A projecting member for forming a constricted portion is provided at a predetermined position in the circumferential direction of the fluid chamber, and a partition of the rubber elastic body that partitions the pair of fluid chambers on both sides of the inner cylindrical fitting has a shear force of 1 kgf / mm or less. A fluid-filled bush, wherein thin-film portions each having a spring constant are provided, and the deformation rigidity in the bulging direction of the partition portion is substantially smaller than the side walls on both axial sides of the fluid chamber. .