JPH0681974B2 - Fluid filled anti-vibration bush - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fluid filled type vibration damping bush, and particularly to both low frequency vibration and high frequency vibration input in a radial direction (a direction perpendicular to an axis). The present invention relates to a fluid-filled type vibration damping bush capable of exhibiting a good vibration damping effect.

(Prior Art) In a bush type vibration-proof support (vibration-proof bush) that is used by being inserted in a vibration system of an automobile or the like, vibrations mainly input in the radial direction thereof are attenuated or blocked. There is something. Examples include suspension bushes for automobiles and cylindrical engine mounts for FF (front engine / front drive) vehicles.

By the way, such an anti-vibration bush is required to exhibit good damping characteristics for low-frequency, large-amplitude vibrations that are input in the radial direction, while providing good isolation for high-frequency, small-amplitude vibrations. Generally, it is required to show the characteristics, but in the conventional vibration-proof bushing, the vibration-proof function against the input vibration was obtained only based on the elastic deformation of the rubber elastic body. Therefore, it is difficult to satisfy those requirements at the same time, and there is a problem that a sufficient damping effect cannot be obtained particularly for vibrations of low frequency and large amplitude.

On the other hand, in contrast, in recent years, (a) the inner tubular member and (b)
An outer cylinder member arranged concentrically or eccentrically outside the inner cylinder member, and (c) facing each other with the inner cylinder member interposed between the inner cylinder member and the outer cylinder member. And a cylindrical rubber elastic body having a pair of pocket portions that are open to the outer peripheral surface and are located in the region where (d) the pair of pocket portions of the rubber elastic body are fluid-tightly closed by the outer cylindrical member. A first and a second fluid chamber, in which a predetermined incompressible fluid is enclosed, and (e) a predetermined throttle passage that allows the first and second fluid chambers to communicate with each other. In addition, so-called fluid-filled vibration damping bushes have been proposed.

According to such a fluid filled type vibration damping bush, the incompressible fluids filled in the first and second fluid chambers flow mutually through the throttle passage, so that the cross sectional area and the length of the throttle passage are increased. The input vibrations in the frequency range corresponding to the ratio can be effectively suppressed (damped or cut off), and therefore the cross-sectional area and length of the throttle passage are set corresponding to the low frequency range ( Tuning)
A good damping effect can be obtained for low-frequency, large-amplitude input vibration.

(Problem) However, although such a conventional fluid-filled type vibration damping bush has a good vibration damping function for input vibration in the frequency range corresponding to the tuning frequency of the throttle passage, It cannot be said that a good vibration-damping function is necessarily obtained with respect to input vibration in the frequency range.In particular, for input vibration in the frequency range higher than the tuning frequency range of the throttle passage, incompressible fluid will pass through the throttle passage. Since it becomes difficult to flow, there is a problem that the anti-vibration function deteriorates. Therefore, as described above, when the ratio of the cross-sectional area to the length of the throttle passage is set to correspond to the low frequency range, there is a problem that the cutoff function for high frequency small amplitude vibration is deteriorated.

(Solution) Against such a background, the present invention is a fluid-filled type capable of exhibiting a good vibration damping effect on both low-frequency large-amplitude vibration and high-frequency small-amplitude vibration input in the radial direction. It was made to provide an anti-vibration bush,
The gist thereof is, as described above, (a) inner cylinder member, (b) outer cylinder member, (c) rubber elastic body, (d) first and second fluid chambers, and (e) ) In a fluid-filled type vibration damping bush including a throttle passage, a predetermined amount is provided in a state in which it extends toward the outer cylinder member side into at least a first fluid chamber of the first and second fluid chambers. Is provided on the inner cylinder member, and in a state of protruding laterally from the tip end side portion of the projection member, a predetermined distance is provided between the corresponding inner wall surface of the rubber elastic body extending in the vibration input direction of the corresponding fluid chamber. While providing a flange portion that forms a gap portion, a through hole penetrating in the bush axial direction is formed in at least one of the rubber elastic body portions that separate the first and second fluid chambers in the circumferential direction, and the through hole is formed. Swelling the rubber elastic body part separating the hole and the second fluid chamber Of the rubber elastic body portion forming the partition wall of the second fluid chamber by configuring the rubber thin film as an effective rubber thin film so as to bridge between the inner cylinder member and the outer cylinder member. At least a part thereof is made of a bulgeable rubber thin film.

(Operation / Effect) With such a fluid filled type vibration damping bush, as in the conventional fluid filled type vibration damping bush, the non-compressible fluid filled in the first and second fluid chambers flows through the throttle passage. Based on this, it is possible to effectively isolate (attenuate or block) the input vibration in the frequency range corresponding to the ratio of the cross-sectional area and the length of the throttle passage.

According to the fluid filled type vibration damping bush according to the present invention,
In at least the first fluid chamber of the first and second fluid chambers, the projecting member is provided on the inner tubular member in a state of extending toward the outer tubular member side, and from the tip end side portion of the projecting member to the lateral side. Since the flange portion is formed in a projecting state and a predetermined gap is formed between the flange portion and the inner wall surface of the corresponding fluid chamber extending in the vibration input direction, the flange portion is enclosed in the corresponding fluid chamber. Since the incompressible fluid flows through the gap in the radial direction of the bush, the input vibration in the frequency range corresponding to the ratio of the sectional area to the length of the gap can be effectively damped.

That is, according to the fluid filled type vibration damping bushing according to the present invention, by setting (tuning) the cross-sectional area and the length of the throttle passage communicating with the first and second fluid chambers in correspondence with a low frequency, Similar to the fluid filled type vibration damping bush, it is possible to obtain good damping characteristics for low frequency and large amplitude vibrations, and by setting the cross-sectional area and length of the gap to correspond to high frequencies. Therefore, it is possible to obtain a good cutoff characteristic against vibration of high frequency and small amplitude.

Moreover, in the fluid filled type vibration damping bushing according to the present invention, at least a part of the rubber elastic body portion forming the partition wall of the second fluid chamber is made of a rubber thin film capable of bulging by the through hole penetrating in the bush axial direction. The rubber thin film connected to the inner cylinder member is positively expanded and contracted by the relative displacement of the inner cylinder member with respect to the outer cylinder member, so that the second fluid chamber of the second fluid chamber against the input vibration load is While the volume change is positively made, the volume change amount, and thus the volume change amount of both the first and second fluid chambers, can be effectively made large, and the incompressible fluid flowing in the throttle passage can be changed. Since the flow rate for the same vibration input load is made larger than before, the anti-vibration function based on the positive flow of the incompressible fluid in the throttle passage is
That is, there is also an advantage that the second fluid chamber is greatly improved as compared with a case where a part of the second fluid chamber is not defined by a rubber thin film.

(Examples) In order to more specifically clarify the present invention,
An embodiment will be described in detail with reference to the drawings.

In addition, although the case where the present invention is applied to a cylindrical engine mount for an FF vehicle will be described here, not only the engine mount for an FF vehicle according to the present invention, but also other protections such as a suspension bush in an automobile suspension are described. Of course, it can be applied to the swing bush.

That is, FIGS. 1 to 3 show an example of a cylindrical engine mount for an FF vehicle according to the present invention.

In these figures, 10 and 12 are an inner tubular metal member as an inner tubular member and an outer tubular metal member as an outer tubular member, respectively, which are arranged eccentrically by a predetermined amount in the mount radial direction (bushing radial direction). , Are elastically connected by a cylindrical rubber elastic body 14 interposed therebetween. Further, the engine mount of the present embodiment is externally mounted on the mounting shaft of the inner tubular metal fitting 10 on the vehicle body side or the power unit side including the engine, while the outer tubular metal fitting 12 is mounted on the power unit side or the vehicle body side tubular holding portion. It is inserted into and attached to the vehicle, so that the power unit can be supported in a vibration-proof manner with respect to the vehicle body.

The rubber elastic body 14 is integrally vulcanized and bonded to the inner cylindrical metal fitting 10, while the rubber elastic body 14 is integrally vulcanized and adhered to the outer peripheral surface of the outer cylindrical metal fitting 12 in a substantially cylindrical seal sleeve 16. It is integrally assembled, and by this, the metal fittings 10 and 12 are elastically connected.

In addition, the engine mount of this embodiment is usually an inner cylinder metal fitting.
The eccentric direction of 10 and the outer tubular metal fitting 12 is the input direction of the vibration load, and when the weight of the power unit is loaded, the inner tubular metal fitting 10 and the outer tubular metal fitting 12 are substantially concentric,
It will be interposed between the vehicle body and the power unit.
In addition, in a usage mode in which the weight of the power unit is not loaded, it is possible to arrange the both metal fittings 10 and 12 concentrically in advance.

Here, the seal sleeve 16 integrally vulcanized and bonded to the outer peripheral surface of the rubber elastic body 14 has an eccentricity between the inner tubular metal fitting 10 and the outer tubular metal fitting 12 as shown in FIGS. 4 to 6. A pair of rectangular windows 18 and 18 are formed so as to face each other in the direction, and the windows 18 and 18 are formed on the outer peripheral side in a state in which the corresponding circumferential ends of the windows 18 and 18 communicate with each other. A pair of groove portions 20, 20 having the same width and the same depth to be opened are formed. Then, in the rubber elastic body 14, the first and second pocket portions 22 of a predetermined depth having a rectangular cross section corresponding to the window portions 18 are formed with the window portions 18 and 18 serving as openings, respectively. , 24 are formed, and the first pocket portion 24 is located at a portion adjacent to the second pocket portion 24 in the mount circumferential direction, and is easily bulged and deformed between the second pocket portion 24 and the second pocket portion 24. A rubber thin film 26 is formed. A pair of through holes 28, 28 penetrating in the axial direction are formed, and the second pocket portion 24 is located at a portion sandwiching the axial direction of the mount,
A pair of recesses 32, 32 that form a second rubber thin film 30 that is easily bulged and deformed are formed between the recesses 32 and 32, respectively.

In this embodiment, the rubber elastic body 14 is housed in each groove 20, 20 of the rubber elastic body 14 (seal sleeve 16) as shown in FIGS. 1 to 3. In this state, arc-shaped orifice members 36 each having a predetermined orifice groove 34 on the outer peripheral surface are assembled, and
The outer cylindrical metal fitting 12 is fitted and integrally assembled to the rubber elastic body 14 in which the orifice members 36, 36 are assembled, and thus the first and second pocket portions 22, 24 are formed. First and second fluid chambers 38, 40 respectively serving as fluid storage spaces are formed, and a pair of orifice passages 42, 42 serving as throttle passages each having an orifice groove 34 of each orifice member 36 as a fluid passage are formed. Has been formed.

More specifically, the orifice groove 34 of each orifice member 36
As shown in FIGS. 7 to 9, in a state where both ends of the orifice member 36 in the circumferential direction are communicated with each other, the orifice member 36 has an S-shape with a length approximately three times the circumferential length. When the orifice member 36 is bent, the pocket portions 22 and 24 of the rubber elastic body 14 are communicated with each other when the orifice member 36 is assembled to the groove portion 20. In the present embodiment, such an orifice groove 34
Rubber elastic body assembled with orifice member 36 having
The outer cylinder metal fitting 12 integrally provided with a seal rubber layer 44 having a predetermined thickness on the inner peripheral surface of 14 is press-fitted, subjected to octagonal drawing, and then drawn using a predetermined die, and fitted. The pocket portions 22, 24 of the rubber elastic body 14 and the orifice grooves 34 of the orifice members 36, 36 are fluid-tightly closed by this, and the first and second fluid chambers 38 are formed. , 40 and a pair of orifice passages 42, 42 are formed.

The press-fitting of the outer cylinder fitting 12 and the eight-way drawing operation, which are performed prior to the drawing process using the die, are usually performed in a predetermined incompressible fluid. This allows each fluid chamber 3
At the same time as the formation of 8, 40, a predetermined incompressible fluid such as water, polyalkylene glycol, silicone oil, etc. is enclosed in the fluid chambers 38, 40.

Further, here, the pair of orifice passages 42 (orifice grooves 34) serving as the throttle passages are set (tuned) corresponding to a frequency having a low ratio of the sectional area (total sectional area) to the length.
The engine shake corresponding to the tuning frequency is based on the flow action or the inertial mass effect when the incompressible fluid enclosed in each fluid chamber 38, 40 flows through these orifice passages 42, 42. Vibrations in the low frequency range, such as, are properly isolated (attenuated or blocked).

Further, although not shown, annular seal lips are formed on the inner peripheral surfaces of both ends in the axial direction of the seal rubber layer 44, and the seal lips are pressed against the seal sleeve 16. Each fluid chamber 38,40
The fluid tightness of the orifice passages 42, 42 is ensured.

By the way, as shown in FIGS. 4 to 6, a longitudinal stopper block 48 is integrally fitted in the central hole of the inner cylindrical metal member 10 in the axial center direction. As a result, each one end portion (50, 50) of the stopper block 48 in the longitudinal direction is projected into the first and second fluid chambers 38, 40 with a predetermined height.
As a result, when an excessive vibration load is input in the eccentric direction between the inner tubular metal fitting 10 and the outer tubular metal fitting 12, the stopper block 4 is projected into the respective fluid chambers 38, 40.
When the protruding portions 50, 50 of 8 come into contact with the outer cylindrical metal fitting 12, excessive displacement of the both metal fittings 10, 12 in the eccentric direction is prevented.

Further, in this embodiment, as shown in FIGS. 1 and 2, with respect to the tip end surface of each protruding portion 50 of the stopper block 48 protruding into each of the fluid chambers 38, 40, as shown in FIGS. A rectangular stopper plate 52 having a predetermined thickness is integrally fixed in a state in which the peripheral portions of the projecting portion 50 project from the respective side surfaces in a predetermined dimension, and the stopper plates 52 are thereby fixed.
A rectangular annular gap 54 having a predetermined cross-sectional area is formed between the peripheral edge of 52 and the wall surface of each corresponding fluid chamber.

When the inner tubular member 10 and the outer tubular member 12 relatively move in their eccentric directions, the incompressible fluids enclosed in the first and second fluid chambers 38, 40 are mounted through the corresponding gaps 54. It is designed to flow in the radial direction.
The vibrations input in the eccentric direction between the inner tubular member 10 and the outer tubular member 12 are also dampened (damped or blocked) based on the flow of 4, 54. Further, as apparent from the above description, in the present embodiment, the protruding portions 50 of each stopper block 48 including a part of each corresponding stopper plate 52 constitute protruding members,
Further, the peripheral edge portion of the stopper plate 52 protruding laterally from the side surface of each protruding portion 50 constitutes a flange portion.

In this embodiment, as shown in FIGS. 1 and 2, the wall surfaces of the fluid chambers 38, 40 that form the gap 54 between the peripheral edge of the corresponding stopper plate 52 ( The side wall surfaces of the pocket portions 22 and 24 are formed so as to extend parallel to the eccentric direction of the inner tubular metal member 10 and the outer tubular metal member 12, respectively. When relatively moved in the eccentric direction, the cross-sectional area of each gap 54 formed between them is kept as constant as possible. In this embodiment, the ratio of the cross-sectional area to the length of each of the gaps 54 is set (tuned) corresponding to the relatively high same frequency, and the incompressible fluid is applied to the gaps 54, 54. Through the gaps 54, 54 when tuning the gaps 54, 54 based on the flow action of the incompressible fluid flowing through the gaps 54, 54 or the inertial mass effect. Vibrations in a relatively high frequency range corresponding to the frequency are well isolated.

Further, as shown in FIG. 1 and FIG. 2, each stopper plate 52 in this case is in a state of covering the metal plate 56 bent in a substantially arc shape and the outer surface of the metal plate 56. The buffer block 58 is integrally vulcanized and formed, and the stopper block 48 is formed on the metal plate 56.
Each protrusion 50 is fixed with a screw 60.

Further, each protruding portion 50 of the stopper block 48 has a rectangular cross section here, and each side surface is made to face the side wall surface of the corresponding pocket portion 22, 24 at a predetermined distance. ing. Further, as is apparent from the above description, each protruding portion 50 of the stopper block 48 is brought into contact with the outer cylindrical metal fitting 12 via the stopper plate 52 as described above.

In the engine mount having such a structure, in the first and second fluid chambers in the eccentric direction of the inner tubular metal fitting 10 and the outer tubular metal fitting 12.
When vibration is input in the opposite direction of 38, 40, those fluid chambers 3
Since the orifice passages 42, 42 that connect the 8 and 40 to each other are tuned to correspond to the low frequency such as the engine shake, as described above, the input vibrations are in the low frequency range such as the engine shake. In such a case, the incompressible fluids enclosed in the fluid chambers 38, 40 are caused to flow to each other through the orifice passages 42, 42. Therefore, similar to the conventional fluid filled engine mount, based on the flow action or the inertial mass effect of the incompressible fluid flowing through the orifice passages 42, 42,
Input vibrations of low frequency and large amplitude such as engine shake corresponding to the tuning frequencies of the orifice passages 42, 42 are advantageously damped.

Then, in the present embodiment, as described above, the second fluid chamber 40
A part of the partition wall is composed of a pair of first and second rubber thin films 26 and 30 which are easily bulged and deformed, and the first rubber thin film 26 among such rubber thin films is the inner tubular metal fitting 10 Is connected to the outer tubular fitting 12 and therefore the inner tubular fitting 10 is connected to the outer tubular fitting 12.
According to the relative displacement of the first rubber thin film 26, positive expansion and contraction are applied to the first rubber thin film 26. Therefore, such a rubber thin film is not used as the partition wall of the second fluid chamber 40. In comparison with the above, while the volume change of the second fluid chamber 40 with respect to the vibration input load is positively performed, the volume change amount, and by extension, both the first and second fluid chambers 38, 40.
Since the volume change amount of the orifices can be effectively made large, and the flow rate of the incompressible fluid flowing through the orifice passages 42, 42 with respect to the same vibration input load is made larger than that of the conventional orifices. The anti-vibration function based on the flow action or the inertial mass effect of the incompressible fluid flowing through the passages 42, 42 is remarkably superior to the conventional one.

On the other hand, when the vibration input in the eccentric direction between the inner tubular metal fitting 10 and the outer tubular metal fitting 12 is in a relatively high frequency range such as muffled sound or engine transmitted sound, the orifice passages 42, 42 have low frequencies. Since the non-compressible fluid is prevented from flowing through the orifice passages 42, 42 because it is tuned to the above, in this case, as described above, in each fluid chamber
Since the gaps 54, 54 in the 38, 40 are tuned to a relatively high frequency range, the incompressible fluids in the fluid chambers 38, 40 are elastically deformed in accordance with the elastic deformation of the rubber elastic body 14. Since the incompressible fluid flows through the gaps 54, 54, the input vibration in the high frequency range is effectively blocked.

That is, according to the engine mount of the present embodiment, while ensuring good damping characteristics for low-frequency, large-amplitude input vibrations such as engine shake, it is possible to reduce high-frequency, small-amplitude input vibrations such as muffled sound and engine transmitted sound. On the other hand, a good cutoff characteristic can be obtained, and further, the damping characteristic with respect to input vibration of low frequency and large amplitude can be greatly improved as compared with the conventional case.

In the present embodiment, as described above, the side wall surfaces of the pocket portions 22 and 24 that form the gap portion 54 with the corresponding stopper plate 52 are formed by the inner tubular metal fitting 10 and the outer tubular metal fitting 12, respectively. It is formed so as to extend in the eccentric direction, and both metal fittings 10,1
When the 2 is relatively moved in the eccentric direction by the input vibration, the cross-sectional area of each gap 54 is kept as constant as possible. There is an advantage that the anti-vibration function based on the flow of the fluids 54 and 54 can be stably obtained against the vibration in the frequency range targeted for anti-vibration.

Further, in the present embodiment, as described above, the throttle passage is formed by being divided into two orifice passages 42, 42, and each orifice passage 42 is bent in an S shape to form each orifice member 36. Since the length of the throttle passage (orifice passage 42) is made as long as possible by this, the flow rate of the incompressible fluid (orifice passages 42, 42) with respect to the vibration input load is Increased by
Therefore, this also has an advantage that the vibration isolation function for the input vibration in the low frequency range is improved.

Although one embodiment of the present invention has been described in detail above, it should be understood that this is a literal example and the present invention should not be construed as being limited to such a specific example.

For example, in the above-described embodiment, the stopper plate 52 is constructed as a member separate from the stopper block 48, but it is also possible to construct them as an integral member.

Further, in the above embodiment, both the first and second fluid chambers 38, 4
Although the case where the gap portions 54, 54 in 0 are tuned to the same frequency has been described, it is also possible to tune the gap portions 54, 54 to frequencies different from each other, and only one of the fluid chambers 38 is It is also possible to form a large gap 54.

Furthermore, in the above-mentioned embodiment, each pair of first and second rubber thin films 26, 30 are used as the rubber thin films that define the second fluid chamber 40.
However, it is also possible to use only the first rubber thin film 26 as the rubber thin film.

In addition, although it is omitted to enumerate specific examples one by one, such as the formation of the throttle passage, the present invention is based on the knowledge of those skilled in the art, and various changes, modifications and improvements are made within the scope not departing from the spirit thereof. It goes without saying that the present invention can be carried out in a mode in which the above is applied.

[Brief description of drawings]

FIG. 1 is a cross-sectional view (I-I cross-sectional view in FIG. 2) showing an example of a cylindrical engine mount for an FF vehicle according to the present invention.
2 and 3 are a II-II sectional view and a III-III sectional view in FIG. 1, respectively. Fourth
FIGS. 5, 5 and 6 are sectional views corresponding to FIG. 1, a sectional view corresponding to FIG. 1 and a sectional view corresponding to FIG. 2, respectively, showing an integrally vulcanized molded article of a rubber elastic body in the engine mount of FIG. It is sectional drawing corresponding to FIG. 7 and 8 are a side view and a plan view showing the orifice member in the engine mount of FIG. 1, respectively, and FIG. 9 is a sectional view taken along line IX-IX in FIG. 10: Inner tube fitting (inner tube member) 12: Outer tube fitting (outer tube member) 14: Rubber elastic body, 16: Seal sleeve 22, 24: Pocket part 26,30: Rubber thin film, 28: Through hole 32: Concave Place: 36: Orifice member 38: First fluid chamber, 40: Second fluid chamber 42: Orifice passage (throttle passage) 48: Stopper block, 50: Projection portion 52: Stopper plate, 54: Gap portion

Claims (1)

[Claims] 1. An (a) inner cylinder member, and (b) an outer cylinder member concentrically or eccentrically arranged outside the inner cylinder member.
(C) A tubular shape provided with a pair of pocket portions that are interposed between the inner tubular member and the outer tubular member and that are located at positions facing each other with the inner tubular member sandwiched therebetween and that open to the outer peripheral surface. A rubber elastic body, and (d) a first and a second sealed with a predetermined incompressible fluid formed by fluid-tightly closing a pair of pocket portions of the rubber elastic body by the outer cylinder member. Of the first and second fluid chambers, wherein (e) a predetermined throttle passage for communicating the first and second fluid chambers with each other is provided. In a state of extending toward the outer cylinder member side in at least a first fluid chamber of the inner cylinder member, and in a state of protruding laterally from a tip side portion of the protrusion member. , In the vibration input direction of the corresponding fluid chamber in the rubber elastic body While providing a flange portion that forms a predetermined gap with the extending inner wall surface, at least one of the rubber elastic body portions that separate the first and second fluid chambers in the circumferential direction penetrates in the bush axial direction. A through-hole is formed, and a rubber elastic body part that separates the through-hole and the second fluid chamber is made into a bulgeable rubber thin film, and the rubber thin film is provided between the inner cylinder member and the outer cylinder member. Is configured so as to bridge, and at least a part of the rubber elastic body portion forming the partition wall of the second fluid chamber is formed of a swellable rubber thin film. bush.