JPH01153831A - Fluid sealed type vibration isolating bush - Google Patents

Abstract

PURPOSE:To favorably damp down low frequency- and large amplitude oscillation by providing a side extending portion which forms a defined constricted portion between an orifice for mutually connecting a balance chamber and a pressure receiving chamber and the inner wall of the pressure receiving chamber. CONSTITUTION:An inner cylinder fixture 10 and an outer cylinder fixture 16 are elastically linked together by means of a nearly semicylindrical rubber elastic body 14. A pressure receiving chamber 44 and a pair of balance chambers 46, 48 use a pocket portion 32 and the spaces of recessed portions 40, 42 as fluid housing spaces respectively. Orifices 50, 52 connects the pressure receiving chamber 44 and the balancing chambers 46, 48 respectively. An annular restricted portion 67 is formed between the outer peripheral edge portion of a side extend-out member 66 ana the inner wall of the pressure receiving chamber 44. Thereby, a favorable damping effect for a low frequency- and large amplitude can be obtained while obtaining a favorable cutting effect for a high-frequency small amplitude.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a fluid-filled vibration-isolating bushing, and more specifically, to a fluid-filled vibration-isolating bushing that has good vibration-isolating function against both low-frequency vibrations and high-frequency vibrations input in the radial direction. This invention relates to a fluid-filled anti-vibration bushing that can exhibit the following characteristics.

(Prior art) A type of vibration-proof bushing that is interposed between a predetermined mounting shaft and a cylindrical holding part that constitute a vibration transmission system, and connects them in a vibration-proof manner. Some devices are designed to attenuate or block input vibrations. Examples include suspension bushings for automobiles and cylindrical engine mounts for FF (front engine/front drive) cars.

By the way, such anti-vibration bushings are required to have good isolation performance against high-frequency, small-amplitude input vibrations, but are also required to have good damping performance against low-frequency, large-amplitude input vibrations. However, in conventional anti-vibration bushings, the anti-vibration function against these input vibrations was exclusively based on the elastic deformation of the rubber elastic body. It is difficult to satisfy this requirement, and there is a problem in that a sufficient damping effect cannot be exerted particularly against input vibrations of low frequency and large amplitude.

Therefore, in recent years, in Japanese Patent Publication No. 48-36151 and Japanese Patent Publication No. 52-16554, a pair of fluid chambers are formed in a cylindrical rubber elastic body so as to face each other in the vibration input direction, and the fluid chambers are A fluid-filled vibration-proof bushing has been proposed in which the two fluid chambers communicate with each other through an orifice so that predetermined incompressible fluids contained in each fluid chamber can mutually flow through the orifice when vibration is input in the radial direction. ing.

According to such a fluid-filled vibration-proof bushing, input vibration in a frequency range set (tuned) for the orifice is suppressed based on the inertial mass effect or liquid column resonance effect of the incompressible fluid flowing through the orifice. Therefore, by setting the tuning frequency of the orifice to a low frequency, it is possible to exhibit a good damping effect against low frequency and large amplitude input vibrations.

(Problem to be solved) However, as mentioned above, such conventional fluid-filled vibration-proof bushings cannot provide good damping for input vibrations in the frequency range (tuning frequency range) set for the orifice. However, it is difficult to say that a good vibration isolation function can be obtained against input vibrations in other frequency ranges, especially for input vibrations in a frequency range higher than the tuning frequency range of the orifice. With respect to vibration, there is a problem in that the incompressible fluid becomes difficult to flow through the orifice, and the vibration damping function is rather deteriorated.

(Solution Means) The present invention was made against the background of the above, and is characterized by a fluid-filled type that blocks or damps vibrations input in the radial direction, as described above. The anti-vibration bushing includes (a) an inner cylinder member, (b) an outer cylinder member disposed concentrically or eccentrically on the outside of the inner cylinder member, and (C) a combination of the inner cylinder member and the outer cylinder member. (d) a rubber elastic body having a pocket portion open on the outer circumferential surface, which is interposed between and connects them; and (d) the inner cylinder member and the outer cylinder member are connected by the rubber elastic body. (e
) a pressure receiving chamber filled with a predetermined incompressible fluid, which is formed by fluid-tightly closing the opening of the pocket portion of the rubber elastic body with the outer cylindrical member;
(f) Similar to the pressure-receiving chamber, which is defined at least in part by a thin wall portion that is easily bulged and deformed in a through space provided between the inner cylinder member and the outer cylinder member. (g) an orifice that allows the equilibrium chamber and the pressure receiving chamber to communicate with each other; and (h) an orifice that projects from the bottom of the pocket portion into the pressure receiving chamber. The present invention is configured to include a lateral extending portion extending from the protruding portion to the side of the protruding portion and forming a predetermined narrowing portion with the inner wall of the pressure receiving chamber.

(Operations/Effects) According to the fluid-filled anti-vibration bushing according to the present invention,
As with conventional fluid-filled vibration-isolating bushings, by setting the tuning frequency of the orifice to a low frequency, the pressure receiving chamber is Low frequency input in the direction opposite to the through hole in the direction of the axis of the bushing.
This means that large amplitude vibrations can be well damped.

On the other hand, as mentioned above, if the tuning frequency of the orifice is set to a low frequency, when the vibration applied manually in the opposite direction between the pressure receiving chamber and the through space in the bushing axis direction is of high frequency and small amplitude, , it becomes difficult for an incompressible fluid to flow through the orifice, and therefore the reduction in dynamic spring constant achieved by flowing an incompressible fluid through the orifice is hardly expected. However, in this case,
By allowing the incompressible fluid to flow in the bush radial direction through the constriction formed between the lateral extension and the wall of the pressure receiving chamber, the length and cross-sectional area of the constriction can be increased. By setting (tuning) according to the frequency, high frequency and small amplitude input vibrations can be effectively blocked based on the inertial mass effect or liquid column resonance effect of the incompressible fluid flowing through the constriction. This makes it possible.

In other words, according to the fluid-filled vibration-isolating bushing according to the present invention, low-frequency and large-amplitude vibrations input in the bushing radial direction can be suppressed by the inertial mass effect of the incompressible fluid flowing through the orifice or liquid column resonance. Based on the action, it can exhibit a good damping effect like the conventional fluid-filled vibration-isolating bushing, but it also has a good damping effect against high-frequency and small-amplitude input vibrations.
Better than conventional fluid-filled vibration damping bushings based on the inertial mass effect or liquid column resonance effect of the incompressible fluid flowing through the constriction formed between the lateral extension and the wall of the pressure receiving chamber. Therefore, it becomes possible to exhibit a vibration isolation function superior to the conventional one against human vibration in the radial direction of the bushing.

(Example) Hereinafter, in order to clarify the present invention more specifically,
The present invention is FF (front engine/front drive)
An example of application to a cylindrical engine mount used for anti-vibration support of a vehicle power unit will be described in detail with reference to the drawings.

First, in FIGS. 1 to 3, 10 and 16 are
Each of them includes a cylindrical inner metal fitting as an inner cylinder member and a cylindrical outer metal fitting as an outer cylinder member, which are arranged eccentrically by a predetermined amount in the radial direction of the mount, and are interposed between them. They are elastically connected by a rubber elastic body 14 having a substantially semi-cylindrical shape. The engine mount of this embodiment is fitted on the outer circumferential surface of the outer cylinder fitting 16 into a cylindrical holding part on the side of the power unit containing the engine or on the car body side, and is attached to the inner hole 18 of the inner cylinder fitting 10 on the side of the car body. Alternatively, it is attached by being inserted externally to the mounting shaft on the power unit side, so that the power unit is supported against vibration against the vehicle body.

Here, the rubber elastic body 14 includes the inner cylinder fitting 10 and the outer cylinder fitting 1.
The metal fittings 10.16 are interposed between the two metal fittings 10.16 on the side where the eccentric distance from the tube is larger, and the mount is interposed between the two metal fittings 10. A cavity 34 having a substantially arc-shaped cross section is formed so as to penetrate in the axial direction. When the power unit is installed, the rubber elastic body 14 is compressed and deformed in the eccentric direction between the inner cylinder fitting 10 and the outer cylinder fitting 16, so that when the power unit is installed, In this case, the inner cylindrical metal fitting 10 and the outer cylindrical metal fitting 16 are positioned substantially concentrically.

Further, the rubber elastic body 14 is integrally vulcanized and bonded to the outer circumferential surface of the inner cylindrical fitting 10 on its inner circumferential surface, and the seal sleeve 12 is attached to the outer circumferential surface in a state that includes the cavity 34. It is vulcanized and sealed in one piece. The outer cylindrical fitting 16 is disposed so as to be fluid-tightly fitted onto the outer peripheral surface of the seal sleeve 12.

As shown in FIGS. 4 to 7, the seal sleeve 12 is fixed to the outer peripheral surface of the rubber elastic body 14, and the inner cylinder fitting 10 is sandwiched between the two fittings 10 and 16 in the eccentric direction. A pair of windows 20, 22 are formed so as to face each other, and a pair of circumferential orifices is formed on the outer peripheral surface of the seal sleeve 12, connecting the windows 20, 2. Grooves 24° and 26 are formed. Further, on the outer peripheral surface of the outer cylinder fitting 16 excluding the openings of the orifice grooves 24 and 26, a sealing rubber layer 30 of a predetermined thickness and having sealing lips 28 and 28 at both ends in the axial direction is made of a rubber elastic material. It is vulcanized and disposed integrally with 14.

On the other hand, as shown in FIGS. 4 and 5, the rubber elastic body 14 is formed with a pocket 32 having a predetermined depth and opening into the window 20 of the seal sleeve 12. . Further, the seal sleeve 12 facing the cavity 34
Rubber elastic membranes 36 and 38 are provided as thin wall portions that are easily bulged and deformed in such a manner that both circumferentially separated end portions of the mount of the other window portion 22 of the seal sleeve 12 are closed from the inside. are integrally vulcanized and bonded, thereby forming a pair of recesses 40 and 42 of a predetermined depth, opening into the window portion 22 of the sealing sleeve I2. As is clear from FIGS. 4 and 5, the window portion 22 of the seal sleeve 12 between the recesses 40 and 42 is made of rubber having a predetermined thickness that is integrally formed with the rubber elastic membranes 36 and 38. covered with layers.

And here, as mentioned above, the sealing sleeve 12
By fitting the outer cylinder fitting 16 in a fluid-tight manner, the openings of the window portion 20.22, the pocket portion 32 and the recess 40.42 are respectively fluid-tightly closed, and the pockets are closed. A pressure receiving chamber 44 and a pair of balance chambers 46, 48 are formed, each of which uses the space within the portion 32 and the recess 40, 42 as a fluid storage space. Further, the openings of the orifice grooves 24 and 26 are fluid-tightly closed by the outer cylinder fitting 16, so that the pressure receiving chamber 44 and each equilibrium chamber 46.
An orifice 50° 52 is formed that communicates with 48. Furthermore, here, the fitting operation of the outer cylindrical fitting 16 to the seal sleeve 12 is performed in a predetermined incompressible fluid, so that the pressure receiving chamber 44 and each equilibrium chamber 46
．． A predetermined incompressible fluid such as water, alkylene glycol, polyalkylene glycol, or a low molecular weight polymer is sealed within 48 .

Note that the outer cylindrical metal fitting 16 is fixed to the seal sleeve 12 by being subjected to a helical drawing process. Further, in the engine mount of this embodiment, after the fitting operation of the outer cylinder metal fitting 16, the outer diameter dimension is set to a desired size by passing through a predetermined die. I
After the fitting operation in step 6, it is also possible to tighten the outer cylindrical fitting 16 to set its outer diameter to a desired dimension. Furthermore, the cross-sectional area and length of the orifices 50.52 are set (tuned) in response to vibrations in a predetermined low frequency range, so that the orifices 50.52.
Based on the inertial mass effect or liquid column resonance effect of the incompressible fluid flowing through the orifice 52 or located there, vibrations in the low frequency range corresponding to the tuning frequency of the orifice 50 and 52 are well damped. It is now possible to

By the way, as shown in FIGS. 4 to 6, on the outer circumferential surface of the inner cylindrical fitting 10, there is a portion located at the center in the axial direction, and the longitudinal direction is in the eccentric direction of the fitting 10°16. A stopper metal fitting 54 in the form of a longitudinal block having a predetermined length is press-fitted and fixed in the central hole 56 in a state corresponding to the above. Both ends 58 in the longitudinal direction of this stopper fitting 54.
60 are made to protrude into the pocket portion 32 (pressure receiving chamber 44) and the cavity 34 at a predetermined height, respectively, so that both ends 58 and 60 of the stopper metal fitting 54 are connected to the outer cylindrical metal fitting 16. Based on the contact with the inner circumferential surface, excessive relative displacement between the inner cylinder fitting 10 and the outer cylinder fitting 16 in the eccentric direction is prevented. Note that the surface of the stopper fitting 54 extending into the cavity 34 is covered with a buffering rubber layer of a predetermined thickness that is molded integrally with the rubber elastic body 14.

Here, as shown in FIGS. 4 and 5, a female screw hole 62 is formed in the end surface of the end portion 58 of the stopper fitting 54 extending into the pocket portion 32 (pressure receiving chamber 44). As shown in FIGS. 1 and 2, a male screw 6 is screwed into the female screw 662.
4, so that the outer peripheral edge extends laterally around the end 58, in other words, the outer peripheral edge extends from the side surface of the end 58 of the stopper fitting 54 in a predetermined direction in the mount axis direction and in the mount circumferential direction. A rectangular plate-shaped lateral extending member 66 having a substantially arcuate cross section is fixed in a protruding state.

In this embodiment, an annular narrowed portion 67 is formed between the outer peripheral edge of the side extending member 66 and the inner wall of the pressure receiving chamber 44, substantially perpendicular to the eccentric direction of the metal fittings 10.16. When the inner cylindrical fitting 10 and the outer cylindrical fitting 16 are caused to move relative to each other in their eccentric direction due to vibration input, the incompressible fluid in the pressure receiving chamber 44 passes through the narrowed portion 67 and moves in the radial direction of the mount. It is designed to be made to flow.

Note that the narrowed portion 67 is formed in the vibration input direction (both metal fittings 10
．． The length 21 (see FIGS. 1 and 2) in the eccentric direction of the orifice 50.
The tuning frequency is set to correspond to a frequency higher than the tuning frequency of Based on the resonance effect, input vibrations in a high frequency range corresponding to the tuning frequency of the narrowed portion 67 can be effectively blocked.

Further, as shown in FIGS. 1 and 2, the side extending member 66 is integrated with a reinforcing metal fitting 68 fixed to the stopper part 58 by a male screw 64, and an outer surface of the reinforcing metal fitting 68. It consists of a vulcanized buffer rubber layer 70 of a predetermined thickness, and a through hole 72 is formed in the buffer rubber layer 70 for screwing the male screw 64 into the female screw 662.

Furthermore, as is clear from the above description, in this embodiment, one end 58 of the stopper fitting 54 is connected to the pocket portion 3.
The end portion 5 of the stopper fitting 54 constitutes a protruding portion that protrudes into the pressure receiving chamber 44 from the bottom of the stopper fitting 54.
The outer circumferential edge portion of the lateral extending member 66 that protrudes laterally from the side surface of the pressure receiving chamber 8 constitutes a lateral extending portion that forms a narrowed portion 67 with the inner wall of the pressure receiving chamber 44 .

Therefore, according to the engine mount with this structure,
When low-frequency, large-amplitude vibration in the opposing direction of the pressure receiving chamber 44 and the cavity 34 is input between the inner cylindrical metal fitting 10 and the outer cylindrical metal fitting 16, based on the elastic deformation of the rubber elastic body 14, Pressure receiving chamber 4
4 and each equilibrium chamber 46° 48 between the orifice 50.52
An incompressible fluid is forced to flow through the
Similar to conventional fluid-filled engine mounts, the low frequency and large amplitude of the inertial mass effect or liquid column resonance of the incompressible fluid flowing through or located in the orifices 50, 52 The vibrations will be well damped.

On the other hand, if the vibration input in the opposite direction between the pressure receiving chamber 44 and the cavity 34 is of high frequency and small amplitude, it becomes difficult for the incompressible fluid to flow through the orifice 50, 52. As a result, the reduction in dynamic spring constant achieved by flowing an incompressible fluid through the orifices 50, 52 can hardly be expected. However, in this case, since the incompressible fluid in the pressure receiving chamber 44 is allowed to flow in the radial direction of the mount through the narrowed part 67, the side of the incompressible fluid located in the narrowed part 67 is Based on the inertial mass effect or liquid column resonance effect according to the relative flow action on the horizontally extending member 66,
The high frequency and small amplitude vibrations are effectively blocked. In other words, compared to a conventional fluid-filled engine mount that does not have such a constricted portion 67, high-frequency
This greatly improves the effectiveness of blocking small amplitude vibrations.

As described above, the cylindrical engine mount according to this embodiment has a good damping effect as in the conventional case against low frequency and large amplitude vibrations input in the opposite direction between the pressure receiving chamber 44 and the cavity 34. At the same time, it is also able to exhibit a better isolation effect than conventional mounts against high-frequency, small-amplitude vibrations, so it is more effective than conventional mounts in blocking vibrations input in the radial direction of the mount. It can be attenuated or cut off.

In the engine mount of this embodiment, as described above, when the power unit is installed, the rubber elastic body 14 is compressed in the eccentric direction of the fitting 10.16, and the pressure receiving chamber 44 and the air space are compressed. Since the ends 58 and 60 of the stopper fitting 54 extended into the space 34 come into contact with the outer cylindrical fitting 16, excessive displacement between the inner cylindrical fitting 10 and the outer cylindrical fitting 16 is effectively prevented. Therefore, there is an advantage that both excessive tensile deformation and compressive deformation of the rubber elastic body 14 are effectively prevented, and the durability of the rubber elastic body 14 and, by extension, the engine mount is improved.

Although one embodiment of the present invention has been described in detail above, this is merely an example, and the present invention is not to be construed as being limited to such a specific example, and within the scope of the spirit thereof, It goes without saying that the present invention can be implemented with various changes, modifications, improvements, etc.

For example, in the embodiment described above, the side extending member 66 constituting the side extending portion was configured separately from the stopper fitting 54, but the side extending member 66, that is, the side extending member 66 The reinforcing metal fitting 68 can also be constructed integrally with the strike/seven bar metal fitting 54. Further, the lateral extending portion that forms the narrowed portion 67 with the inner wall of the pressure receiving chamber 44 does not need to extend laterally around the entire circumference of the protruding portion 58 of the stopper fitting 54 as a protruding portion. For example, the end 58 of the stopper fitting 54
It is also possible to form a narrowed portion 67 by providing a lateral extending portion extending only in the circumferential direction of the mount (circumferential direction of the bush) from the side surface of the bushing.

Furthermore, the protrusion that supports the lateral extension includes the rubber elastic body 1
It is also possible to configure it with a rubber block integrated with 4.
Further, the protrusion does not necessarily need to have a stopper function for regulating excessive relative displacement between the inner cylinder fitting 10 and the outer cylinder fitting 16.

Further, in the embodiment described above, the recesses 40.42 constituting the equilibrium chambers 46,48 were formed with openings formed in each of the windows 22 of the seal sleeve 12; The recesses 40 and 42 of .48 can also be formed with mutually independent windows formed in the sealing sleeve 12 as openings, and the recesses 40 and 42 of .
It is also possible to form 6.48 as one equilibrium chamber, and furthermore it is also possible to employ only one of the equilibrium chambers 46.48 as an equilibrium chamber.

Further, in the embodiment described above, the rubber elastic membrane 36, 38 as a thin wall portion defining a part of the equilibrium chamber 46, 48 was provided integrally bonded to the sealing sleeve 12, but the thin wall portion is The thin wall portion does not necessarily have to be integrally bonded to the sealing sleeve, but may be formed separately from the sealing sleeve and mechanically attached to the sealing sleeve to form an equilibrium chamber. is also possible.

Further, in the embodiment described above, the inner tube fitting 10 and the outer tube fitting 16 are arranged eccentrically by a predetermined amount in the radial direction of the mount, but it is also possible to arrange them concentrically.

In addition, in the embodiment described above, the present invention was applied to a cylindrical engine mount for a front-wheel drive vehicle. It can also be applied to bushings and anti-vibration mounts.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of a cylindrical engine mount for a front-wheel drive vehicle according to the present invention, and FIGS. be. FIG. 4 is a sectional view corresponding to FIG. 1 showing an integrally vulcanized product of the rubber elastic body in the engine mount of FIG. 1, and FIGS. 5, 6, and 7 are respectively They are a V-V cross-sectional view, a VT-Vl cross-sectional view, and a ■-■ cross-sectional view. 10: Inner tube fitting (inner tube member) 12: Seal sleeve 14: Rubber elastic body 16: Outer tube fitting (outer tube member) 32: Pocket portion 34: Space 36.38: Rubber elastic membrane (thin wall portion) 40 , 42: Recess 44: Pressure receiving chamber 46. 48: Equilibrium chamber 50.

Claims (1)

[Scope of Claims] An inner cylindrical member, an outer cylindrical member disposed concentrically or eccentrically outside the inner cylindrical member, and an outer cylindrical member interposed between the inner cylindrical member and the outer cylindrical member. a rubber elastic body having a pocket portion opened on the outer circumferential surface, which connects the inner cylinder member and the outer cylinder member, and a bushing provided in a portion not connected by the rubber elastic body between the inner cylinder member and the outer cylinder member in the axial direction of the bush. a pressure-receiving chamber in which a predetermined incompressible fluid is enclosed, which is formed by fluid-tightly closing the opening of the pocket portion of the rubber elastic body with the outer cylindrical member; , a non-contact space similar to the pressure receiving chamber, which is defined at least in part by a thin wall portion that is easily bulged and deformed in a through space provided between the inner cylinder member and the outer cylinder member; an equilibrium chamber in which a compressible fluid is sealed; an orifice that allows the equilibrium chamber and the pressure receiving chamber to communicate with each other; Extended laterally,
A fluid-filled vibration damping bushing comprising: a lateral extending portion forming a predetermined narrowed portion with an inner wall of the pressure receiving chamber.