JP2507404Y2 - Fluid-filled mounting device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fluid-filled mount device, and more particularly to a fluid-filled mount device that can be preferably used as an automobile engine mount or the like.

(Prior Art) Conventionally, in an engine mount for supporting an automobile engine unit in a vibration-proof manner, generally, in order to prevent vibration due to a shake or a bounce phenomenon, a high damping performance against an input vibration of a low frequency and a large amplitude, and idling. In order to prevent noise and vibration during running, traveling, etc., low dynamic spring performance against high-frequency, small-amplitude input vibration is required.

Therefore, in recent years, as a type of such an engine mount, in JP-A-57-9340, etc., first and second supports disposed at a predetermined distance in the vibration input direction, and the first and second supports are provided. A partition wall extending in a direction substantially perpendicular to the vibration input direction is provided inside the device provided with a rubber elastic body that elastically connects the two supports, and the incompressible fluid is provided on both sides of the partition wall. Forming two fluid chambers (pressure-receiving chamber and equilibrium chamber) in which the fluid is enclosed, and an orifice passage between the pressure-receiving chamber and the equilibrium chamber for communicating the two fluid chambers with each other, and a fluid pressure difference There has been proposed a so-called fluid-filled mount device having a structure in which a movable member arranged so as to be displaced or deformed by a predetermined amount in the direction of absorbing is provided.

That is, in the fluid-filled mount device having such a structure, when a low-frequency, large-amplitude vibration is input, the movable member is displacement-controlled and does not function, and a fluid flow occurs through the orifice passage. The high damping effect can be exerted by the flow action or the liquid column resonance action of the above, and on the other hand, at the time of the vibration input of the high frequency small amplitude, the liquid pressure increase in the pressure receiving chamber due to the closing of the orifice passage. The low dynamic spring characteristics can be exhibited by being absorbed by the displacement or deformation of the movable member.

(Problem to be Solved) However, in the antivibration mount device having such a structure, the hydraulic pressure absorption effect of the movable member in the pressure receiving chamber can be effectively exhibited only in a relatively narrow tuned frequency range, and particularly When vibration is input in a frequency range that is higher than the tuning frequency range, the hydraulic pressure in the pressure receiving chamber cannot be effectively exerted on the movable member, and virtually no function can be achieved. However, there was an inherent problem that the anti-vibration effect was significantly reduced due to the significant increase in

(Solution) Here, the present invention has been made in view of the above-mentioned circumstances, and is characterized in that a first support body is arranged at a predetermined distance in a vibration input direction. And a second support body are elastically connected by a rubber elastic body, and a partition wall that is arranged in a direction substantially perpendicular to the vibration input direction is sandwiched between them to receive the vibration to be isolated. A chamber on the side of the first support and a variable volume equilibrium chamber defined at least in part by a flexible film on the side of the second support, and forming a pressure-receiving chamber and a balance chamber. While enclosing a predetermined incompressible fluid, between the pressure receiving chamber and the equilibrium chamber, an orifice passage that connects the two fluid chambers to each other and a predetermined amount of displacement in the direction that absorbs the fluid pressure difference between the two fluid chambers. Is a fluid filled with a movable member that is arranged to be deformable. In the mounting device, the rubber elastic body is formed into a solid substantially circular truncated cone shape, and the small diameter side thereof is connected to the first support body, and the large diameter side thereof is connected to the second support body, respectively, By forming a concave portion having an opening on the large-diameter side end surface and a concave portion having a predetermined depth which is opened at the central portion of the concave portion and extends in the vibration input direction, the concave portion and the concave portion include Between the large-diameter side end surface and the partition wall, from the opening of the recess to the top of the recessed portion as the inner surface length of the free length portion of the peripheral wall of the pressure receiving chamber, the peripheral wall of the pressure receiving chamber vibrates. This is to enable shear deformation in the direction of eliminating the internal pressure of the pressure receiving chamber when inputting.

(Examples) 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 shows an example in which the present invention is applied to an automobile engine mount. In this figure, 10 and 12 are first and second support fittings, respectively, which are arranged facing each other with a predetermined distance in the main vibration input direction (vertical direction in the drawing). And
The first support fitting 10 is formed in a substantially flat plate shape having a plurality of mounting holes 14 in the outer peripheral edge portion.
Further, the second support fitting 12 is a tubular fitting 18 having a substantially cylindrical shape,
By the bottom metal fitting 20 having a substantially bottomed cylindrical shape, the opening peripheral edge portion of the bottom metal fitting 20 is formed by being caulked and integrated with the peripheral edge portion of the tubular metal fitting 18 on the one axial end side. A mounting bolt 22 projecting on the bottom surface of the bottom metal fitting 20 is integrally provided.

Then, the first support metal fitting 10 and the second support metal fitting 12
As shown in the drawing, with respect to the first support fitting 10, in a state where the internal space of the second support fitting 12 is open,
The first support fitting 10 and the second support fitting 12 are elastically coupled by a rubber elastic body 24 in such a state that they are opposed to each other at a predetermined distance. It is integrated as one. And
Such an engine mount is the first such support bracket.
The mounting holes 14 of 10 and the mounting bolts 22 of the second support bracket 12 are mounted on one of the vehicle body side and the power unit side including the engine, respectively, thereby protecting the power unit from the vehicle body. It is designed to support shaking.

Here, the rubber elastic body 24 has a solid substantially frustoconical shape in which a slightly recessed concave portion 25 is formed on the large-diameter side end surface, and the first support fitting is formed on the small-diameter side end surface. It is formed as an integrally vulcanized molded product which is vulcanized and adhered to the tubular metal fitting 18 constituting the second support metal fitting 12 and at the peripheral portion on the large diameter side.

In addition, the rubber elastic body is attached to the second support fitting 12.
The outer peripheral edge portion is fluid-tightly sandwiched between the tubular metal fitting 18 and the bottom metal fitting 20 so as to face the large-diameter side end surface of the 24 at a predetermined distance, and is used as a flexible film. Diaphragm 26
Are provided, whereby a sealed space is formed between the rubber elastic body 24 and the diaphragm 26.
A space 28 that allows the deformation of the diaphragm 26 is formed between the diaphragm 26 and the bottom fitting 20.

In addition, a predetermined incompressible fluid such as water, polyalkylene glycol, silicone oil, etc. is enclosed in this closed space.

Further, in the closed space, a partition member 30 having a substantially disc shape is superposed on the diaphragm 26 on the side of the first support fitting 10, and together with the diaphragm 26,
Between the cylindrical metal fitting 18 and the bottom metal fitting 20 constituting the second support metal fitting 12, by sandwiching the peripheral edge portion, the enclosed space is partitioned in a direction perpendicular to the vibration input direction. As a result, such a sealed space is formed on the rubber elastic body 24 (first support metal fitting 10) side into which the pressure-receiving chamber 32 to which the vibration to be isolated is inputted and the diaphragm 26 (second support metal fitting). It is divided into two fluid chambers, the equilibrium chamber 34 having a variable volume on the 12) side by elastic deformation of the diaphragm 26.

Here, the partition member 30 is formed of a hard material such as metal or resin, and has a thick outer peripheral portion that is open to one side in the axial direction and extends for less than one round in the circumferential direction. A circumferential groove 36 is formed to extend, and a shallow circular recess 38 that opens to the other side in the axial direction is formed in the thin central portion.

When the partition member 30 is assembled to the second support fitting 12 as described above, the opening of the circumferential groove 36 is closed, and as a result, the circumferential groove 36 is closed.
At 36, both ends are communicated with the pressure receiving chamber 32 or the equilibrium chamber 34 through the communication holes 39, respectively, and the pressure receiving chamber 32 and the equilibrium chamber 34 are communicated with each other. The orifice passage 40 having a length is formed.

On the other hand, at the time of assembling to the second support fitting 12, the closing member 42 that closes the opening of the circular recess 38 is assembled to the partition member 30, so that the accommodation space in the circular recess 38. 44 is formed, and a thin disk-shaped movable plate 46 is provided in the accommodation space 44.
However, it is accommodated and arranged so as to be displaceable by a predetermined amount in the vibration input direction in a state where the moving end can be regulated by contact with the inner wall surface of the accommodation space 44. Further, each of the partition member 30 and the closing member 42 is provided with a plurality of communication holes 48 of a predetermined size that communicate the inside of the accommodation space 44 with the pressure receiving chamber 32 or the equilibrium chamber 34, respectively. Through the hole 48, the hydraulic pressure in the pressure receiving chamber 32 and the equilibrium chamber 34 is exerted on the accommodation space 44.

Then, in such an engine mount, when the vibration is input, the internal pressure fluctuation is induced in the pressure receiving chamber 32 based on the elastic deformation of the rubber elastic body 24, while the internal pressure of the balance chamber 34 is changed. Since the volume change is allowed by the deformation of the diaphragm 26, the internal pressure fluctuation can be substantially avoided, and thus the pressure receiving chamber 32 and the equilibrium chamber 34
Based on the internal pressure difference between the orifice passage 40 and the fluid passage through the communication hole 48 due to the displacement of the movable plate 46, the fluid flow through the orifice passage 40 and the flow passage of the orifice passage 40 are well known. The vibration damping characteristics due to the flow resistance or liquid column resonance of the fluid flowing through and the low dynamic spring characteristics due to the absorption of hydraulic pressure in the pressure receiving chamber 32 due to the displacement of the movable plate 46 are respectively the vibration input of the tuned frequency. It can be demonstrated in time.

In the present embodiment, the orifice passage 40
The cross-sectional area and length in the case where the input vibration in the low frequency range corresponding to the generated frequency of engine shake or bounce, specifically, in the frequency range around 10 Hz, can exhibit excellent damping ability. On the other hand, the flow cross-sectional area and the length of the communication hole 48 in the hydraulic pressure absorbing mechanism including the movable plate 46 are set in a high frequency range where vibration isolation capability is required for the mount, specifically, With respect to the input vibration in a predetermined frequency range within the range of about 50 to 200 Hz, it is set so that a low dynamic spring can be achieved, and the displacement amount of the movable plate 46 relative to the inner surface of the accommodation space 44. It is set so as not to substantially function as a decompression absorption mechanism when a low-frequency large-amplitude vibration is input, which is regulated to a predetermined amount by abutment and which requires vibration damping capability of the orifice passage 40. It, the vibration damping capacity by the orifice passage 40 with respect to the input vibrations of such a low frequency range is adapted to be secured.

By the way, here, in such an engine mount, as shown in FIG. 1, in the rubber elastic body 24 formed with the above-mentioned solid truncated cone shape, in the central portion of the large diameter side end face thereof. A circular hole-shaped recessed portion 50 extending at a predetermined depth in the axial direction that is the vibration input direction is formed. Then, by the recessed portion 50, the large-diameter side end surface that constitutes the inner wall surface of the pressure receiving chamber 32 in the rubber elastic body 24 is formed with a stepped inner surface shape in the axial direction,
The rubber elastic body 24 constitutes a wall portion of the pressure receiving chamber 32 on the side of the first support fitting 10, and the pressure receiving chamber 32 has the concave portion 50.
It is also configured to include.

That is, in the hydraulic pressure absorption mechanism including the movable plate 46, when the vibration input in a frequency range higher than the set frequency, the communication hole 48 is closed, so that it cannot substantially function, and therefore However, in the engine mount according to the present embodiment, which is provided with the rubber elastic body 24 having the above-described shape, the rubber elastic body 24 is used. Configured pressure receiving chamber
By positively utilizing the transverse wave surging phenomenon caused in the wall portion of 32, it is possible to avoid an increase in the mount dynamic spring constant.

More specifically, in such an engine mount, both ends of the wall portion of the pressure receiving chamber 32 formed of the rubber elastic body 24 are restrained by the first support metal fitting 10 and the second support metal fitting 12. It is possible to consider that the shear wave phenomenon, which is a kind of resonance phenomenon, is generated at a predetermined frequency on the basis of the fluctuation of the internal pressure of the pressure receiving chamber 32 when the vibration is input to the wall portion. It will be born in the area. Then, under the condition that such a surging phenomenon occurs, when the vibration is input, the rubber elastic body 24 forming the wall portion of the pressure receiving chamber 32 is sheared and deformed in the direction to eliminate the internal pressure in the pressure receiving chamber 32. Therefore, the reduction of the vibration transmissibility and the dynamic spring constant can be effectively achieved.

By the way, the frequency f that causes such a surging phenomenon is set according to the following equation.

l: Free length of the rubber elastic body 24 forming the wall of the pressure receiving chamber 32 G: Transverse elastic coefficient (dynamic shear modulus) of the rubber elastic body 24 forming the wall of the pressure receiving chamber 32 ρ: Rubber elastic body 24 In the engine mount of the present embodiment, the inner surface length of the wall of the pressure receiving chamber 32: l ₂ can be set to a large value by the recess 50, so that the rubber elastic body 24 is free. Long: l can be large.

Therefore, in the engine mount configured as described above, the free length of the wall portion of the pressure receiving chamber 32 can be changed without changing the material surface such as the lateral elastic coefficient: G and the density: ρ of the rubber elastic body 24. : l can be set to a large value, so that the frequency at which the shear wave surging phenomenon occurs can be reduced while ensuring the durability and load bearing characteristics of the rubber elastic body 24, and the surging occurrence frequency can be reduced. , The frequency range where the anti-vibration performance is required for the mount, specifically 200
It is possible to set it up to about 800Hz.

Then, the hydraulic pressure absorption mechanism including the movable plate 46 cannot substantially function because the communication hole 48 is closed, and the frequency is higher than the frequency set for the hydraulic pressure absorption mechanism. When the vibration of the area is input, the internal pressure in the pressure receiving chamber 32 rises, and the pressure receiving chamber is formed by the rubber elastic body 24.
This can be effectively reduced by the surging phenomenon in the wall portion of 32, and thus, the reduction of the mount spring constant can be effectively achieved at the time of such vibration input in the high frequency range. In addition, in particular, in the engine mount according to the present embodiment, the inner surface length: l ₂ of the wall portion of the pressure receiving chamber 32 is set to have substantially the same length as the outer surface length: l _1, and the surging phenomenon Can be exhibited more effectively.

By the way, in the engine mount having the structure according to the present embodiment, the surging occurrence frequency of the wall portion of the pressure receiving chamber 32 is
The result of measuring the frequency characteristic of the dynamic spring (absolute spring: | ^* K |) when set to 600 Hz is shown in FIG. In this figure, as a case where the surging phenomenon of the wall portion is not exhibited, the results of a similar experiment using an engine mount in which the fluid is not sealed in the pressure receiving chamber 32 are also shown as a comparative example. Has been done. Also from this figure, it is easy to understand the effect of reducing the mount dynamic spring characteristic due to the surging phenomenon in the wall portion of the pressure receiving chamber 32 constituted by the rubber elastic body 24.

Further, in such an engine mount, when the inner surface length: l ₂ of the rubber elastic body 24 forming the wall portion of the pressure receiving chamber 32 is set to be large so that the free length: l is set to be large, the rubber In the elastic body 24, the thickness of the large-diameter side portion, which will generate a large stress when a vibration is input, can be advantageously secured, so that the durability and load bearing characteristics of the mount can be more advantageously secured. It will be.

Further, in the engine mount according to this embodiment, the cylindrical metal fitting 18 to which the large-diameter side peripheral portion of the rubber elastic body 24 is fixed.
Inner flange part whose end peripheral edge is bent inward in the radial direction
52, the adhesion surface of the rubber elastic body 24 is formed with a surface perpendicular to the main vibration input direction, whereby the rubber elastic body is locally deformed by the input load in the vicinity of the fixed portion. And stress concentrations can be effectively avoided.

In addition, in such an engine mount, by increasing the free length: l of the wall portion of the pressure receiving chamber 32, the shear component exerted on the rubber elastic body 24 at the time of load input will be increased. In particular, in this embodiment,
A thin tapered cylindrical restraint fitting 54 is integrally embedded in the center of the wall of the pressure receiving chamber 32, and the restraint fitting 54 increases the compression component exerted on the rubber elastic body 24 at the time of vibration input. By doing so, the deterioration of durability and creep property of the rubber elastic body 24 can be alleviated or prevented.

Hereinafter, the embodiments of the present invention have been described in detail, but this is a literal example, and the present invention should not be construed as being limited to such specific examples.

For example, the specific structure such as the hydraulic pressure absorption mechanism including the orifice passage 40 and the movable plate 46 is not limited to that of the above-described embodiment, and may be changed according to the characteristics of vibration to be isolated. Should be changed accordingly.

Further, it goes without saying that the present invention as described above can be advantageously applied as a vibration isolation mount device in various devices other than the above-mentioned automobile engine mount.

Although not listed one by one, the present invention can be implemented in variously modified, modified, improved, etc. modes based on the knowledge of those skilled in the art. It goes without saying that all of them are included in the scope of the present invention without departing from the spirit.

(Operation / Effect) As is apparent from the above description, in the present invention, for example, a portion forming the wall portion of the pressure receiving chamber while maintaining its durability and load bearing characteristics with respect to the rubber elastic body. It is possible to set a sufficiently large free length in the pressure receiving chamber wall portion formed by such a rubber elastic body, which can advantageously cause surging as a resonance phenomenon against input vibration. It is possible to set the generated frequency to a practical frequency range in which a vibration damping function is required for the mount device.

Therefore, in the mounting device having the structure according to the present invention, the surging frequency in the pressure receiving chamber wall is
By setting the high frequency range in which the movable member cannot substantially function, it is possible to effectively avoid a significant increase in the internal pressure in the pressure receiving chamber at the time of vibration input in the high frequency range. The increase of the mount dynamic spring constant at the time of vibration input can be suppressed to a low level, and thus the vibration transmissibility can be effectively reduced.

The idea of reducing the mount dynamic spring constant by positively utilizing the surging phenomenon in the rubber elastic body that constitutes the wall portion of the hydraulic pressure increase in the pressure receiving chamber in this way to reduce or eliminate it. Has not been realized in the past.By realizing this idea, it is possible to effectively improve the anti-vibration characteristics at high frequency vibration input without adding new mount components. The great technical significance of the present invention lies in the achievement of the above.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional explanatory view showing an example in which the present invention is applied to an automobile engine mount, and FIG. 2 shows a result of measuring a frequency characteristic of an absolute spring in the engine mount together with a comparative example. It is a graph. 10: First support metal fitting, 12: Second support metal fitting 24: Rubber elastic body, 26 ... Diaphragm 30: Partition member, 32: Pressure receiving chamber 34: Equilibrium chamber, 40: Orifice passage 46: Movable plate, 48: Communication Hole 50: Recess, 52: Inner flange 54: Restraint

Claims (1)

(57) [Scope of utility model registration request] 1. A rubber elastic body for elastically connecting a first support and a second support, which are arranged at a predetermined distance in the vibration input direction, and which are substantially perpendicular to the vibration input direction. With a partition wall disposed in the direction, a pressure-receiving chamber into which vibration to be isolated is input is provided on the side of the first support, and at least a part of which is defined by a flexible membrane, which is a variable volume balance. Chambers are respectively formed on the side of the second support, and a predetermined incompressible fluid is enclosed in the pressure receiving chamber and the equilibrium chamber, while the fluid chambers are mutually connected between the pressure receiving chamber and the equilibrium chamber. A fluid-filled mount device, comprising: an orifice passage that communicates with the movable member; and a movable member that is displaceable or deformable by a predetermined amount in a direction that absorbs a fluid pressure difference between the two fluid chambers. Formed in the shape of a real truncated cone,
The small-diameter side is connected to the first support and the large-diameter side is connected to the second support, respectively, and a concave portion is opened on the large-diameter side end face and a central portion of the concave portion is opened to vibrate. By forming a recess having a predetermined depth extending in the input direction, the pressure receiving chamber is formed between the partition wall and the large-diameter side end surface of the rubber elastic body, including the recess and the recess. The inner wall length of the pressure receiving chamber from the opening of the recess to the top of the recess is defined as the inner surface length of the free length portion of the peripheral wall of the pressure receiving chamber. A fluid-filled mount device characterized by being capable of being shear-deformed in the direction.