JPH0470497B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluid-filled bushing that performs the function of damping vibrations by utilizing the elastic deformation of an elastic body and the flow resistance of the fluid, and in particular, the damping function of the fluid can be adjusted according to the vibration characteristics. It concerns a changing fluid-filled bush.

Conventionally, a fluid-filled bushing that combines the functions of elastic deformation of an elastic body and fluid flow resistance has been developed using an inner cylinder member and an outer cylinder member disposed at a predetermined distance outside the inner cylinder member. , an elastic body made of rubber or something similar provided between the inner cylinder member and the outer cylinder member, and a plurality of fluid chambers formed in the elastic body and filled with a predetermined incompressible fluid; Some devices are known that include a communication path (orifice) that allows the plurality of fluid chambers to communicate with each other.

However, in conventional fluid-filled bushes of this type, the flow cross-sectional area of the orifice remains substantially unchanged, and as a result, there is a limit to the damping characteristics that can be obtained. Generally, when the cross-sectional area of the orifice is selected to be small, the damping coefficient in the low-frequency vibration range becomes large, which is effective in suppressing low-frequency vibration, but the dynamic spring constant against vibration in the high-frequency range increases. , it becomes difficult to obtain a low dynamic spring constant in high wind and wave regions. On the other hand, if the cross-sectional area of the orifice is chosen to be large, the vibration frequency at which the damping effect is maximum shifts to a high frequency range, and the dynamic spring constant around that frequency becomes low, resulting in soft spring characteristics against high-frequency vibrations. The attenuation function in the frequency range cannot be fully fulfilled. Because of this antinomic relationship, no matter how the cross-sectional area of the orifice was chosen, it was difficult to satisfy both high attenuation characteristics in the low frequency range and low dynamic spring constant in the high frequency range. . Therefore, in the past, the anti-vibration function in the high frequency range was often sacrificed.

The present invention was made based on these circumstances, and its purpose is to ensure a low dynamic spring constant in the high frequency range while exhibiting high attenuation performance in the low frequency range. The object of the present invention is to realize a fluid-filled bush with a simple structure.

In order to achieve this object, the present invention allows the cross-sectional area of the orifice to change depending on whether low-frequency vibrations are applied or high-frequency vibrations, and the orifice cross-sectional area is optimized for both frequency ranges. The gist of this is to provide the following. That is, a plurality of elastic bodies made of rubber or the like are interposed between the inner cylinder member and the outer cylinder member as described above, and a predetermined incompressible fluid is sealed in the elastic body. In a fluid-filled bush having a structure in which a fluid chamber is formed and a plurality of fluid chambers are communicated with each other by a communication passage, the plurality of fluid chambers are arranged so as to extend along the bush axis and in the axial direction of the elastic body. The plurality of fluid chambers are arranged symmetrically with respect to the bush axis, and the openings of the fluid chambers at one end in the axial direction of the elastic body are connected. , the communicating path is provided, and at least one of the fluid chambers and the communicating path is provided at a connecting portion with a position where the fluid chamber and the communicating path are blocked by closing the opening, and a position where the fluid chamber and the communicating path are blocked by not closing the opening. A movable member movable in the axial direction of the elastic body is provided between the chamber and a position where communication with the communication path is not interrupted, and the movable member has a flow cross-sectional area smaller than the flow cross-sectional area of the communication path. With this, a communication passage was formed that communicated the communication passage with the fluid chamber.

In this way, by simply moving the movable member disposed at the connecting portion between the fluid chamber and the communication path, the movable member is brought to a position where communication between the fluid chamber and the communication path is cut off when low frequency vibration is applied. As a result, fluid circulation is performed through the communication portion of the movable member having a smaller flow cross-sectional area than the communication path, and high attenuation characteristics in the low frequency range are exhibited. On the other hand, when high-frequency vibrations act, the movable member is kept in a position where it does not block communication between the communication path and the fluid chamber, and the fluid flows through the cross-sectional area of the communication path. A low dynamic spring constant is obtained. In other words, by adopting a simple structure of inserting a movable member, it is possible to provide a larger flow cross-sectional area when high-frequency vibration is applied compared to when low-frequency vibration is applied, and it is as if two types of orifices were used. This means that it has become possible to perform a good damping function from the high frequency range to the low frequency range, and as a result, a multi-functional fluid-filled bushing with excellent compactness can be advantageously realized. I got it.

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

In FIGS. 1 and 2, 2 is a cylindrical inner tube fitting, and a cylindrical outer tube fitting 4, which functions as an outer tube member, is provided on the outside of this metal fitting 2, which functions as an inner tube member. They are placed concentrically and spaced apart. And those inner cylinder fittings 2 and outer cylinder fittings 4
An annular rubber sleeve 6 is fixed and interposed between the two by known vulcanization molding. As is clear from FIG. 1, this rubber sleeve 6, which functions as an elastic member, has a pair of fluid chambers 8 and 10 formed at symmetrical positions with respect to the center line (bush axis) of the inner cylinder fitting 2. . These fluid chambers 8 and 10 have an arcuate cross-sectional shape centered on the center line of the rubber sleeve 6, and as is clear from FIG. long) One end of the fluid chambers 8 and 10 in the axial direction is a dead end within the rubber sleeve 6, while the other end is opened at one end surface of the rubber sleeve 6.

and fluid chambers 8 and 10 of the rubber sleeve 6.
A flat bottomed cylindrical fixing plate 12 is fixed at the bottom of the open end face. This fixing plate 12 has approximately the same diameter as the rubber sleeve 6, and is fitted concentrically to one end of the inner cylindrical metal fitting 2 in a center hole formed at its bottom, using known vulcanization bonding.
It is integrated with the rubber sleeve 6. Furthermore, through holes 14 having shapes corresponding to the openings of the fluid chambers 8 and 10 are formed in the bottom wall portion of the fixing plate 12 at positions corresponding to the openings of the fluid chambers 8 and 10.
These through holes 14 form the openings of the fluid chambers 8 and 10, and therefore, regardless of the elastic deformation of the rubber sleeve 6, the opening area of the openings is always kept constant.

A thin rubber layer 16 is adhered to the entire inner surface of the fixing plate 12 except for the portion of the through hole 14, and an annular spacer plate 18 is attached to the inner surface of the cylindrical portion of the fixing plate 12. 12 and is disposed in a state in which it is in close contact with the bottom wall portion of the inner cylinder fitting 2 and in a state in which it is fitted into one end portion of the inner cylinder fitting 2. This spacer plate 18 functions as a first member and is made of a material that does not easily deform elastically, such as metal or resin.As is clear from FIG. Portions 20 and 22 are formed to penetrate in the thickness direction. As is clear from FIG. 2, these windows 20 and 22 are formed in similar shapes that are slightly larger than the respective through holes 14 of the fixing plate 12, in other words, at positions corresponding to the openings of the fluid chambers 8 and 10. ,
A stepped surface perpendicular to the axis of the inner cylindrical fitting 2 is formed on the opening periphery of the through hole 14 .

The outer surface of this spacer plate 18 has a spacer plate 1 between it and the bottom of the fixing plate 12.
8, hold the metal grooved plate 2
4 is placed. This grooved plate 24 is
Its outer peripheral edge is fitted inside the cylindrical part of the fixing plate 12, while its center hole is fitted into one end of the inner cylindrical metal fitting 2, and the one end is caulked in the direction of diameter expansion, and fixed. plate 12
By caulking the outer peripheral edge of the tip inward, it is integrated with the fixed plate 12 with the spacer plate 18 in between, and the liquid tightness between the three plates 12, 18 and 24 is maintained by the rubber layer 16.
It is maintained by.

The grooved plate 24 closes the windows 20 and 22 of the spacer plate 18 from the side opposite to each through hole 14 of the fixing plate 12, but the surface that is aligned with the outer surface of the spacer plate 18 has a groove on both sides. An annular groove 26 is formed along the circumference passing through the windows 20 and 22, and this annular groove 26 is covered by the outer surface of the spacer plate 18, thereby providing communication between the windows 20 and 22. A passage 28 is formed. That is, in this embodiment, the spacer plate 1 functioning as the first member
8 and a grooved plate 24 functioning as a second member, a communication passage 28 is formed that allows the two fluid chambers 8 and 10 to communicate with each other through the windows 20 and 22. .

The fluid chambers 8 and 10 are each filled with an incompressible fluid such as water or polyalkylene glycol.
allows the incompressible fluid in both fluid chambers 8 and 10 to flow from one to the other and from the other to one.

Windows 20 and 2 of the spacer plate 18
Reference numerals 2 correspond to connecting portions between the communication path 28 and the fluid chambers 8 and 10, respectively. A movable piece 30 in the shape of an arc plate as shown in FIG. 4 is accommodated in one of the window portions 20 that connects the fluid chamber 8 and the communication path 28. As shown in FIG.

This movable piece 30, which functions as a movable member, is made of an elastic body such as metal, resin, or rubber, and is thinner than the spacer plate 18 and has a similar shape that is slightly smaller than the window portion 20. , the through hole 1 serving as the opening of the fluid chamber 8
It has a size that allows it to sit on the peripheral edge of the opening of the hole 4 and close the through hole 14 thereof. Also, this movable piece 3
0 is maintained in a floating state in the axial direction of the inner cylinder fitting 2 between the opening periphery of the through hole 14 and the inner surface of the grooved plate 24, and is located at a position where the through hole 14 is closed and then It is said that it can be moved between a position where it floats up and does not become blocked.

When the movable piece 30 is seated on the peripheral edge of the opening of the through hole 14 and closes it, the fluid chamber 8 and the communication path 2 are closed.
8, this movable piece 30 is formed with a communication hole 32 that penetrates in the thickness direction at a portion facing the through hole 14. The communication hole 32 communicates the fluid chamber 8 and the communication path 28 with a flow cross-sectional area smaller than the flow cross-section area of the communication path 28, and the movable piece 30 communicates with the through-hole 14.
When sitting on the periphery of the opening, the communication hole 32
The cross-sectional area of the orifice becomes the cross-sectional area of the orifice, and when the fluid chamber 8 and the communicating passage 28 are allowed to communicate with each other through the window portion 20 without being seated, the cross-sectional area of the communicating passage 28 becomes the orifice cross-sectional area. Note that even when the movable piece 30 is in contact with the inner surface of the grooved plate 24 , since the movable piece 30 is smaller than the window portion 20 , communication between the fluid chamber 8 and the communication path 28 is limited to the peripheral wall surface of the window portion 20 . and the outer circumferential surface of the movable piece 30.

Such a fluid-filled bush 34 is manufactured, for example, according to the following steps.

First, the inner cylindrical metal fitting 2 and the outer cylindrical metal fitting 4 are placed concentrically in a predetermined mold. Note that the fixing plate 16 is fitted into one end of the inner cylinder fitting 2 without being caulked. Such an inner tube fitting 2 and an outer tube fitting 4
A rubber sleeve 6 having fluid chambers 8 and 10 is filled with a rubber material between the fixing plate 12 and the fixing plate 12.
is vulcanized and bonded to the inner cylindrical fitting 2, outer cylindrical fitting 4, and fixing plate 12 at the same time.
Further, a rubber layer 16 for sealing is vulcanized and molded on the inner surface of the fixing plate 12.

Next, the thus obtained bushing assembly 36 as shown in FIG. 3 is immersed in a liquid tank containing the above-mentioned incompressible fluid. Assembly 36,
The spacer plate 18, movable piece 30, and grooved plate 24 are assembled in sequence, and the inner cylindrical metal fitting 2 and fixed plate 12 are caulked. As a result, the incompressible fluid is sealed in the fluid chambers 8 and 10, the fixed plate 12, the spacer plate 18, and the grooved plate 24 are integrated, and the movable piece 30 is accommodated within the window portion 20. hand,
The result is a fluid-filled bush 34 as shown in FIGS. 1 and 2. Note that, for example, reducing the diameter of the outer cylindrical fitting 4 and applying preliminary compression to the rubber sleeve 6 is effective in increasing its durability.

Such a fluid-filled bush 34 is, for example,
It can be suitably used as a suspension bush in an automobile suspension system. In that case,
The outer cylindrical metal fitting 4 is fitted into the arm eye (boss part) of the control arm, while the inner cylindrical metal fitting 2 has a
As the axle for the vehicle body or wheel side is inserted,
The pair of fluid chambers 8 and 10 are used in a state where they face each other in the direction in which they receive the main vibration load.

When a vibration load of low frequency and large amplitude is applied, the elastic deformation of the rubber sleeve 6 causes the volume of one of the fluid chambers 8 and 10 to decrease and the volume of the other to increase, for example. , the incompressible fluid flows out from the fluid chamber 8 whose volume has decreased, and flows through the communication path 28 to the fluid chamber 10 whose volume has increased.
It flows in the direction of the flow. Furthermore, if the volume decreasing side and volume increasing side are switched, the fluid will flow in the opposite direction to the above, and such behavior will be repeated thereafter. At this time, the movable piece 30 provided on the fluid chamber 8 side is pushed toward the grooved plate 24 side when the fluid flows out from the fluid chamber 8, but when the fluid flows into the fluid chamber 8, the movable piece 30 is pushed toward the grooved plate 24 side.
4 and closes the opening periphery of the movable piece 30. As a result, fluid flows in through the communication hole 32 of the movable piece 30. Therefore, when low-frequency vibrations that cause large displacements act, the flow resistance when the fluid flows through the communication holes 32, which have a smaller flow cross-sectional area than the communication passages 28, provides a large damping function against the low-frequency vibrations. Such vibrations can be effectively damped.

On the other hand, when vibrations in the high frequency range act, the amount of elastic deformation of the rubber sleeve 6 and the amount of flow of incompressible fluid are small, and the force applied to the movable piece 30 is also small, so the movable piece 30 does not move inside the window part 20. It is kept in a floating state and does not close the opening periphery of the through hole 14. Therefore, when high-frequency vibrations are input, the effective flow cross-sectional area of the incompressible fluid is converted to the cross-sectional area of the communication passage 28, which has a larger cross-sectional area than the communication hole 32, compared to when low-frequency vibration is input. Therefore, in the high frequency range, a low dynamic spring constant, in other words, a spring characteristic suitable for absorbing high frequency vibrations can be obtained.

In this way, the cross-sectional area of the orifice that communicates the fluid chambers 8 and 10 is small in the low frequency range and large in the high frequency range, so it is possible to achieve high attenuation characteristics in the low frequency range and high frequency range, which were previously considered difficult. This made it possible to achieve both a low dynamic spring constant and a low dynamic spring constant.

Incidentally, in the embodiment described above, the movable piece 30 was housed only on the side of the window 20 among the windows 20 and 22 of the spacer plate 18, but the movable piece 30 was housed in both the windows 20 and 22, respectively. It is also possible to arrange 30. In this way, in the low frequency vibration range, the communication hole 32 of the movable piece 30 will act as an orifice for both the peaks and troughs of the amplitude, resulting in more effective high damping characteristics. is obtained.

However, the movable piece 30 is not only moved to a position where it closes the opening of the fluid chamber 8 by the incompressible fluid flowing into the fluid chamber 8, but also moved by the incompressible fluid flowing out from the fluid chamber 8 to the opposite side. If the configuration is such that the fluid chamber 8 and the communication path 28 are communicated only through the communication hole 32 when the fluid chamber 8 is moved to the position shown in FIG.
Substantially the same effect as when the movable pieces 30 are provided in each of the two parts can be obtained. In that case, the neutral position of the movable piece 30 is the non-blocking position, and the positions moved to both sides of the neutral position are respectively blocking positions.

Further, in the above embodiment, the space for accommodating the movable piece 30 is formed by the spacer plate 18, and the stepped surface on which the movable piece 30 is seated is formed by the fixed plate 12, but the rubber 6
A space for accommodating such a stepped surface and the movable piece 30 is formed at the end of the side where the fluid chamber 8 opens, and the opening of the space is closed from the outside with a suitable plate member. It is also possible to do so.

Furthermore, it is also possible to form a plurality of communication holes 32 in the movable piece 30 in a range where the sum of their cross-sectional areas is smaller than the cross-sectional area of the communication path 28, or alternatively, instead of the communication holes 32, a plurality of communication holes 32 can be formed in the movable piece 30. It is also possible to form a notch or slit that enters the inside from the outer peripheral edge of the tube to function as a communication section. Note that the movable member is not limited to a small plate-like piece, and for example, a spherical body with a hole can also be employed.

Furthermore, instead of providing two fluid chambers at symmetrical positions, the number of fluid chambers can be increased. In addition to suspension bushes, the present invention can also be applied to fluid-filled bushes as other anti-vibration supports. It goes without saying that the present invention can be practiced with various changes, improvements, combinations, etc. based on knowledge.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of a fluid-filled bushing according to an embodiment of the present invention;
The figure is a - sectional view in FIG. 1. FIG. 3 is a sectional view of a bush assembly obtained in the process of manufacturing the fluid-filled bush shown in FIGS. 1 and 2. FIG. FIG. 4 is an exploded perspective view showing how the main components are assembled to the bush assembly shown in FIG. 3. FIG. 2... Inner tube fitting (inner tube member), 4... Outer tube fitting (outer tube member), 6... Rubber sleeve (elastic body), 8,
10...Fluid chamber, 12...Fixing plate, 14...
...Through hole, 18... Spacer plate (first member), 20, 22... Window portion, 24... Grooved plate (second member), 26... Annular groove, 28... Communication path, 30... Movable piece (movable member), 32... communicating hole (communicating part), 34... fluid filled bush.

Claims (1)

[Scope of Claims] 1. An elastic body made of rubber or its analog is interposed between an inner cylinder member and an outer cylinder member, and a plurality of elastic bodies in which a predetermined incompressible fluid is sealed. In a fluid-filled bush having a structure in which a fluid chamber is formed and the plurality of fluid chambers are communicated with each other by a communication passage, the plurality of fluid chambers are arranged so as to extend along the axis of the bush and along the axis of the elastic body. The plurality of fluid chambers are arranged symmetrically with respect to the bush axis by opening at one end in the axial direction, and further, the openings of the fluid chambers at one end in the axial direction of the elastic body are connected. , the communication passage is provided, and at a connecting portion between at least one of the fluid chambers and the communication passage, there is a position where communication between the fluid chamber and the communication passage is cut off by closing the opening, and a position where the opening is not blocked. A movable member movable in the axial direction of the elastic body is provided between a position where communication between the fluid chamber and the communication path is not interrupted, and the movable member is provided with a movable member that is movable in the axial direction of the elastic body. A fluid-filled bushing characterized in that a communication portion having a small flow cross-sectional area for communicating the communication path and the fluid chamber is formed. 2. The fluid chamber has an opening at one end in the axial direction of the elastic body, and a first member having a larger window corresponding to the opening is configured to inject liquid into the end of the elastic body on the opening side. the movable member is housed in the window in a state where it can be seated on the periphery of the opening of the fluid chamber, and the second member is disposed liquid-tightly outside the first member; 2. The fluid-filled bushing according to claim 1, wherein the communication passage is formed in the mating surfaces of the first member and the second member. 3. The fluid-filled fluid according to claim 1 or 2, wherein the movable member is a plate-shaped member, and the communication path is a communication hole passing through the plate-shaped movable member in the thickness direction. Butsuyuu.