JP2024049766A - Liquid envelope type vibration isolation device - Google Patents

Abstract

[Problem] To improve durability of rubber walls on both axial sides of a liquid chamber in a liquid-sealed cylindrical vibration-proof device having two liquid chambers mutually connected by an orifice passage while ensuring the amount of change in volume of the liquid chamber when vibration is input. [Solution] The cross-sectional shapes of rubber walls 40, 40 of a liquid chamber 34 are made different between the circumferential center portion and both end portions, so that the center portion has a compound curved shape smoothly connecting an inner circumferential curved portion 42 that rises from the inner shaft member 12 side toward the outer periphery side and then curves axially outward, and an outer circumferential curved portion 44 that rises from the outer tubular member 14 side toward the inner periphery side and then curves axially inward, while the both end portions have a single curved shape that rises from the inner shaft member 12 side toward the outer periphery side, then curves axially outward and further extends axially outward. [Selected Figure] Figure 2

Description

The present invention relates to a liquid-sealed cylindrical vibration isolation device that has two liquid chambers that are interconnected by an orifice passage.

A liquid envelope type vibration isolation device has been known as a type of vibration isolation device used in vibration transmission systems. It has two liquid chambers that are connected to each other through an orifice passage, and uses the liquid flow through the orifice passage when vibration is input to obtain a vibration isolation effect.

More specifically, as shown in, for example, JP 2006-250340 A, inside the main rubber elastic body that connects the inner shaft member and the outer cylindrical member, two liquid chambers are formed on either side of the inner shaft member, and when vibration is input between the inner shaft member and the outer cylindrical member in the direction perpendicular to the axis, the elastic deformation of the main rubber elastic body causes a relative liquid pressure difference to occur between the two liquid chambers, which causes liquid to flow through an orifice passage.

However, with conventional liquid envelope type vibration isolation devices, it was difficult to ensure sufficient durability for the rubber walls that make up the walls on both sides of the liquid chamber in the axial direction. In particular, depending on the required characteristics of the vibration isolation device, it may be difficult to set the thickness dimension of the rubber walls sufficiently to increase the volume change of the liquid chamber when vibration is input. Making the rubber walls thinner makes it more difficult to ensure durability, and there is a problem that cracks are more likely to occur.

JP 2006-250340 A

The present invention was made against the background of the above-mentioned circumstances, and the problem to be solved is to provide a liquid-envelope type vibration-damping device with a new structure that has two liquid chambers that are interconnected by an orifice passage, and that can improve the durability of the rubber wall portions on both axial sides of the liquid chamber while ensuring the amount of volume change in the liquid chamber when vibration is input.

A first aspect of the present invention is as follows.
A liquid-sealed vibration-proof device in which an inner shaft member and an outer cylindrical member are connected by a main rubber elastic body, and two liquid chambers are formed on both sides of the inner shaft member in a direction perpendicular to the axis thereof and are mutually communicated with each other through an orifice passage,
the axial cross-sectional shapes of the rubber wall portions constituting the wall portions on both axial sides of the liquid chamber in the main rubber elastic body are different between a central portion and both end portions in the circumferential direction of the liquid chamber,
The central portion has a compound curved shape in which an inner circumferential side curved portion that rises from the inner shaft member side toward the outer circumferential side and then curves axially outwardly and an outer circumferential side curved portion that rises from the outer tubular member side toward the inner circumferential side and then curves axially inwardly are smoothly connected,
A liquid envelope type vibration isolation device characterized in that both end portions rise from the inner shaft member side toward the outer periphery, then curve axially outward and further extend axially outward, forming a single curved shape.

First, in order to solve the problems mentioned above, the inventors conducted extensive research into the optimal shape of the rubber wall of the liquid chamber, but as long as the rubber wall had a constant shape over the entire circumference of the liquid chamber, as in the conventional liquid envelope type vibration isolation device described in Prior Art Document 1, cracks and the like were likely to occur near both ends of the circumferential direction of the liquid chamber, making it difficult to ensure durability. Therefore, the inventors devised a new rubber wall that can achieve excellent durability while ensuring the amount of change in the liquid chamber when vibration is input by making the cross-sectional shapes of the rubber wall different between the central part and both end parts of the circumferential direction of the liquid chamber. This enabled the present invention to be realized.

That is, in the liquid envelope type vibration isolator of this embodiment, the circumferential center part of the liquid chamber is a rubber wall part that spreads in the circumferential direction with a cross-sectional shape that is compound curved, such as an S-shape, as shown in the embodiment described later (see FIG. 2, etc.), while the circumferential both end parts of the liquid chamber are rubber wall parts that spread in the circumferential direction with a cross-sectional shape that is single curved, such as an L-shape, as shown in the embodiment described later (see FIG. 4, etc.). As a result, the central part, which occupies a wide circumferential area of the rubber wall part, is made into a compound curved shape, and the change in the liquid chamber volume when vibration is input is secured, and durability can be improved by the large free length. In addition, the circumferential both end parts of the rubber wall part are made into a simpler single curved shape than the central part, so that, as can be understood from the comparison with the comparative example described later, which has a rubber wall part that extends to the end with a constant shape in the circumferential direction (see FIG. 25, etc.), the free length is secured even under conditions where the effective radial length is limited, and the occurrence of cracks due to local stress concentration is suppressed, and durability can be improved.

As a result, in this liquid envelope type vibration isolation device, instead of the conventional constant cross-sectional shape in the circumferential direction for the rubber wall of the liquid chamber, a new specific cross-sectional shape that varies in the circumferential direction is adopted, making it possible to obtain good durability while ensuring the amount of change in the liquid chamber volume when vibration is input.

A second aspect of the present invention is a liquid envelope type vibration isolation device according to the first aspect,
The main rubber elastic body has a pair of connecting arms extending in an axially perpendicular direction between the inner shaft member and the outer cylindrical member between both circumferential ends of the two liquid chambers, and the two liquid chambers are formed between both circumferential ends of the pair of connecting rubber arms.
Each rubber wall portion of the liquid chamber has a continuous curved portion that is concave axially outward, extending from the inner peripheral edge portion along the outer peripheral surface of the inner shaft member to the circumferential ends of the pair of connecting arms toward the outer tubular member.

In this embodiment of the liquid envelope type vibration isolation device, a continuous curved portion that is concave toward the axial outward direction is provided, and extends continuously from the inner peripheral edge of the circumferential center of the rubber wall portion to both circumferential ends. As will be understood from the embodiments described later (see Figures 1, 2, 3-6, etc.), the inclusion of such a continuous curved portion effectively provides a curved portion with a concave cross section that easily tolerates elastic deformation with a large free length over substantially the entire rubber wall portion of the liquid chamber, which contributes to improving durability.

A third aspect of the present invention is a liquid envelope type vibration isolating device according to the first or second aspect,
The two liquid chambers, including the rubber wall portions, are shaped symmetrically in the radial direction sandwiching the inner shaft member.

The liquid envelope type vibration isolation device of this embodiment can be preferably used in situations where the main vibration load is input in the radial direction in which the two liquid chambers face each other, and where there is almost no preload (static load or bias load) in that radial direction, thereby more effectively and stably ensuring the durability of the rubber wall portions on both axial sides of the two liquid chambers.

A fourth aspect of the present invention is a liquid envelope type vibration isolator according to the second aspect,
The pair of connecting rubber arm portions are provided on a line perpendicular to the axis of the inner shaft member, and the circumferential sizes of the two liquid chambers are the same.
The continuous curved portion provided in the rubber wall portion between the two liquid chambers has a direction and length extending from the inner shaft member side toward the outer cylindrical member side that are different from each other at both longitudinal sides.

This type of liquid envelope vibration isolation device can be used, for example, in cases where different input loads or input vibrations are applied to both sides of the radial direction where the two liquid chambers face each other, or where different vibration isolation characteristics, spring characteristics, load characteristics, etc. are required. By making the shapes and lengths of the continuous curved parts in the two liquid chambers different from each other, it is also possible to tune the spring characteristics and durability of the rubber wall parts of the two liquid chambers.

A fifth aspect of the present invention is a liquid envelope type vibration isolator according to any one of the first to fourth aspects,
An intermediate sleeve is fixed to the outer periphery of the main rubber elastic body,
The main rubber elastic body is provided with two pockets, each of which opens to an outer circumferential surface through a window provided in the intermediate sleeve,
An outer peripheral end of the rubber wall portion is fixed to an axial end edge of the window portion of the intermediate sleeve, and the rubber wall portion is provided between the inner shaft member and the intermediate sleeve,
The outer tubular member is fitted onto and fixed to the intermediate sleeve, and the window portion of the intermediate sleeve is covered with the outer tubular member, thereby forming the two liquid chambers.

In this embodiment of the liquid envelope type vibration isolation device, for example, the main rubber elastic body can be constructed as an integrally vulcanized molded product including an inner shaft member and an intermediate sleeve, and the shape stability of the outer peripheral end of the main rubber elastic body can be achieved by the intermediate sleeve, while the fluid tightness of the liquid chamber can be stably achieved by the outer cylindrical member that is fitted onto the intermediate sleeve. Moreover, by giving the outer peripheral portion of the rubber wall of the liquid chamber a shape that extends from the peripheral edge of the window portion of the intermediate sleeve toward the inner peripheral side and the axial direction, excessive constraint of the rubber wall by the intermediate sleeve can be avoided, and the design freedom of the shape of the rubber wall can be advantageously ensured.

1 is a front view showing a liquid envelope type vibration isolation device according to a first embodiment of the present invention. FIG. Cross-sectional view taken along line II-II in FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. IV-IV cross-sectional view in FIG. 2 is a cross-sectional view taken along the line VV in FIG. 1 . VI-VI cross-sectional view in FIG. FIG. 2 is a cross-sectional view taken at the axial center in FIG. 1 . FIG. 4 is a front view showing a liquid envelope type vibration isolation device according to a second embodiment of the present invention. IX-IX cross-sectional view in FIG. 8 . XX cross-sectional view in FIG. 8 . XI-XI cross-sectional view in FIG. 8 . XII-XII cross-sectional view in Figure 8. XIII-XIII cross-sectional view in FIG. 8 . FIG. 9 is a cross-sectional view taken at the axial center in FIG. 8 . FIG. 4 is a front view showing a liquid envelope type vibration isolation device according to a third embodiment of the present invention. Cross-sectional view taken along the line XVI-XVI in FIG. 15 . Cross-sectional view taken along the line XVII-XVII in FIG. 15 . Cross-sectional view taken along line XVIII-XVIII in Figure 15. Cross-sectional view taken along line XIX-XIX in Figure 15. FIG. 16 is a cross-sectional view taken at the axial center in FIG. 15 . FIG. 4 is a front view showing a liquid envelope type vibration isolation device as a comparative example. Cross-sectional view taken along the line XXII-XXII in Figure 21 . Cross-sectional view taken along line XXIII-XXIII in Figure 21. Cross-sectional view taken along line XXIV-XXIV in Figure 21. Cross-sectional view of XXV-XXV in Figure 21. Cross-sectional view taken along line XXVI-XXVI in Figure 21 . FIG. 22 is a cross-sectional view taken at the axial center in FIG. 21 .

Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, a rubber vulcanization molded product having the characteristics of the invention is shown, and the outer cylindrical member (outer cylindrical metal fitting) that is assembled to the rubber vulcanization molded product to form a liquid chamber and constitute a liquid-envelope type vibration-damping device is shown in phantom lines in the representative drawings.

Figures 1 to 7 show a liquid envelope type vibration isolation device 10 as one embodiment of the present invention. This liquid envelope type vibration isolation device 10 is attached to a vibration transmission system and is not limited to a specific application, but can be used, for example, as a member mount, torque rod mount, suspension bush, engine mount, etc. for vehicles such as automobiles.

The liquid envelope type vibration isolator 10 of this embodiment has an inner tubular metal fitting 12 as an inner shaft member and an outer tubular metal fitting 14 as an outer tubular member arranged at a predetermined distance from each other in the radial direction, and the inner tubular metal fitting 12 and the outer tubular metal fitting 14 are elastically connected by a main rubber elastic body 16. This liquid envelope type vibration isolator 10 is mounted between the power unit and the vehicle body by, for example, attaching the inner tubular metal fitting 12 to the power unit side of the vehicle and attaching the outer tubular metal fitting 14 to the body side of the vehicle in a state where the vertical direction in Figures 1 and 2 is approximately the vertical direction of the vehicle and the left-right direction in Figure 1 is approximately the left-right direction of the vehicle. In this mounted state, the main vibration to be damped is input between the inner tubular metal fitting 12 and the outer tubular metal fitting 14 in the vertical direction in Figure 1. In the following description, the vertical direction and the left-right direction generally refer to the vertical direction and the left-right direction in Figure 1.

More specifically, the inner tubular metal fitting 12 has a rod shape that extends straight. In this embodiment, the inner tubular metal fitting 12 has a cylindrical hollow rod shape with an inner hole for mounting, but the shape of the inner tubular metal fitting 12 can be set according to the member to which it is mounted, and it may be a solid rod shape, for example. Furthermore, the inner tubular metal fitting 12 only needs to have the required strength and rigidity, and can be made of metals such as iron and stainless steel, as well as fiber-reinforced resin, and there is no limit to the material.

A middle sleeve 18 is disposed radially away from the outer periphery of the inner tubular metal fitting 12. The middle sleeve 18 is cylindrical and has a larger diameter and a thinner wall than the inner tubular metal fitting 12. The middle sleeve 18 is preferably made of metal, but the material is not limited, and synthetic resins, as with the inner tubular metal fitting, can also be used. In this embodiment, the inner tubular metal fitting 12 and the middle sleeve 18 are disposed on approximately the same central axis, but the inner tubular metal fitting 12 and the middle sleeve 18 may be disposed eccentrically in the radial direction, taking into account the required vibration-proofing performance in a specific direction, load support characteristics, preload load, etc.

A pair of windows 20, 20 are formed on the intermediate sleeve 18, located on both sides that face each other in the up-down direction. Each window 20 is located in the axial middle and extends in the circumferential direction by a length less than halfway around, and in this embodiment has a substantially rectangular outer peripheral shape. Note that the window 20 is set according to the required characteristics and the like in correspondence with the pocket portion of the main rubber elastic body 16 described below, and is not limited to a specific shape or size.

In addition, in the circumferential region of the intermediate sleeve 18 where the window portions 20, 20 are not formed, the axial middle portion is reduced in diameter to form a pair of concave circumferential grooves 22, 22 that open to the outer circumferential surface and extend in the circumferential direction. As a result, a pair of circumferential grooves 22, 22 is provided that spans between the circumferential edge portions of the pair of window portions 20, 20 and connects the pair of window portions 20, 20 to each other on both circumferential sides.

A main rubber elastic body 16 is disposed between the radially opposing surfaces of the inner tubular metal fitting 12 and the intermediate sleeve 18 and is fixed to the inner tubular metal fitting 12 and the intermediate sleeve 18, and the main rubber elastic body 16 elastically connects the inner tubular metal fitting 12 and the intermediate sleeve 18. The main rubber elastic body 16 has a generally thick cylindrical shape, and in this embodiment, is configured as an integrally vulcanized molded product 24 in which the outer circumferential surface of the inner tubular metal fitting 12 is vulcanized bonded to the inner circumferential surface, and the inner circumferential surface of the intermediate sleeve 18 is vulcanized bonded to the outer circumferential surface. A thin seal rubber layer may be formed integrally with the main rubber elastic body 16 to cover the outer circumferential surface of the intermediate sleeve 18.

The main rubber elastic body 16 is formed with a pair of pockets 26, 26 located on both sides of the inner tubular metal fitting 12 in the vertical direction, each extending in the axial middle portion over a circumferential length less than half the circumference, and formed with a recessed shape that opens onto the outer circumferential surface. The pair of pockets 26, 26 each open onto the outer circumferential surface of the intermediate sleeve 18 through a pair of windows 20, 20 in the intermediate sleeve 18.

In this embodiment, the pair of pockets 26, 26 and the pair of windows 20, 20 have the same shape and size that are symmetrical in the vertical opposing direction, but as can be seen from the third embodiment described below, it is also possible to set the pair of pockets 26, 26 and the window portions 20, 20 to different shapes and sizes on both opposing vertical sides depending on the required characteristics, etc.

Then, by forming the pair of pockets 26, 26, a pair of connecting rubber arms 28, 28 that are located between both circumferential ends of the pair of pockets 26, 26 and connect the inner tube fitting 12 and the outer tube fitting 14 in the axially perpendicular direction are formed in the main rubber elastic body 16. Note that the pair of connecting rubber arms 28, 28 in this embodiment are formed on a straight line in one radial direction extending in the left-right direction across the inner tube fitting 12, but it is also possible to make the circumferential sizes of the pair of pockets 26, 26 different from each other, for example, by making the circumferential lengths of the pair of pockets 26, 26 different from each other, so that the elastic central axes of the pair of connecting rubber arms 28, 28 extend radially outward from the inner tube fitting 12 at a predetermined intersection angle (intersection angle).

In this embodiment, each pocket 26 can be considered as a recess that opens upward or downward. If considered in this way, the bottom wall of the pocket 26 can be interpreted as being composed of the outer peripheral surface of the inner and the circumferential end faces of a pair of connecting rubber arms 28, 28 extending from the inner peripheral surface to the left and right. Both circumferential end faces of the pair of connecting rubber arms 28, 28 that constitute the bottom surface of the pocket 26 are inclined surfaces that extend approximately radially from the central axis of the inner tube fitting 12. As a result, the pocket 26 spreads out in an approximately fan shape at a predetermined angle around the central axis on the outer peripheral side of the inner tube fitting 12. In addition, each of the upper and lower pockets 26, 26 has a cushioning rubber protrusion 29 for a stopper that is located at the center of each bottom and protrudes in the vertical direction on the outer peripheral surface of the inner tube fitting 12, with a protruding height smaller than the depth dimension of the pocket 26.

In addition, the intermediate sleeve 18 has orifice-forming rubbers 30, 30 formed inside the circumferential grooves 22, 22 and fixed to the inner surface of the circumferential grooves 22, 22. Each orifice-forming rubber 30 has an orifice groove 32 formed therein that extends in the circumferential direction, and both ends of the orifice groove 32 are connected to one of the pocket portions 26. The orifice-forming rubbers 30, 30 can be formed integrally with the main rubber elastic body 16, for example.

The integrally vulcanized molded product of the main rubber elastic body 16 as described above is press-fitted into the outer tubular metal fitting 14, and assembled in a state in which the outer tubular metal fitting 14 is fixedly fitted on the outside. The outer tubular metal fitting 14 is cylindrical and slightly larger than the intermediate sleeve 18, and is fitted and fixed to the outer peripheral surface of the intermediate sleeve 18 (see Figs. 1-3 and 8).

The specific shape and structure of the outer tube fitting 14 are not limited. For example, the outer tube fitting 14 may have an inward flange portion and an outward flange portion integrally formed at each axial end of the cylindrical portion that is fitted and fixed to the intermediate sleeve 18, and a stopper cushion rubber that protrudes axially outward may be formed on the outer surface of each flange portion. In addition, the outer tube fitting 14 may have a thin seal rubber layer that covers the entire inner circumferential surface, which may be integrally vulcanized and molded, and the seal may be improved by compressing the seal rubber layer at the fitting surface with the intermediate sleeve 18.

In addition, the integrally vulcanized molded main rubber elastic body 16 can be reduced in diameter by drawing before or during the assembly of the outer metal tube 14, if necessary, to reduce residual stress during vulcanization molding.

In this way, the outer tubular metal fitting 14 is fixed to the integrally vulcanized molded product of the main rubber elastic body 16, thereby covering the outer peripheral openings of the pair of pockets 26, 26 and also covering the outer peripheral openings of the orifice grooves 32, 32. In addition, for example, the outer tubular metal fitting 14 is assembled to the intermediate sleeve 18 in a liquid, and thus a specified liquid such as ethylene glycol is sealed in the pair of pockets 26, 26 and the orifice grooves 32, 32.

As a result, a pair of liquid chambers 34, 34 are formed by the pair of pockets 26, 26, and an orifice passage 36, 36 is formed by the pair of orifice grooves 32, 32, which connects the pair of liquid chambers 34, 34 to each other and allows liquid to flow between the liquid chambers 34, 34. In other words, when the liquid envelope type vibration isolator of this embodiment is mounted on an automobile or the like, and vertical vibration is input between the inner tube metal fitting 12 and the outer tube metal fitting 14, relative fluid pressure fluctuations occur between the pair of upper and lower fluid chambers 34, 34 due to the elastic deformation of the main rubber elastic body 16, and fluid flow is generated through the orifice passages 36, 36 based on this fluid pressure fluctuation. Then, by utilizing the resonant action of this fluid, it is possible to improve the vibration isolation performance against input vibration.

The groove length, groove cross-sectional shape, and overall groove length of the orifice passage 36 can be set according to the required vibration-proofing characteristics, and are not limited to these. For example, the orifice passages 36 on both the left and right sides may be of the same shape, or may be of different shapes. Also, the orifice passage 36 may be formed only inside one of the circumferential grooves 22, and the other circumferential groove 22 may be blocked by the orifice-forming rubber 30. Alternatively, a separate orifice member may be attached to the circumferential groove 22, and the orifice passage may be formed by the orifice member.

Here, the wall portions on both axial sides of each liquid chamber 34 are composed of a pair of rubber wall portions 40, 40 in which the main rubber elastic body 16 is thinned by the pocket portion 26. The end faces on both axial sides of the main rubber elastic body 16 are curved surfaces that are concave toward the inside of the axial direction, and the free surface length in the radial direction extending between the inner tube metal fitting 12 and the outer tube metal fitting 14 is increased, thereby improving durability. In particular, the axial end faces of the main rubber elastic body 16 have different shapes (axial cross-sectional shapes) between the pair of connecting rubber arm portions 28, 28 and the pair of rubber wall portions 40, 40. That is, the axial end faces of the connecting rubber arm portions 28 have a relatively simple curved concave shape as shown in FIG. 3, while the axial end faces of the rubber wall portions 40 have a relatively complex curved concave shape as shown in FIG. 2, etc.

The pair of connecting rubber arm portions 28 have a solid structure that extends in the axial direction with a substantially constant cross-sectional shape between both axial end faces. Meanwhile, the circumferential space between the pair of connecting rubber arm portions 28, 28 is hollowed out by the pocket portions 26, 26 in the axial middle portion. The rubber wall portions 40 that form the walls on both axial sides of each pocket portion 26 extend with a substantially constant thickness dimension throughout, because the axial inner surface shape of the pocket portion 26 corresponds to the axial end face shape of the rubber wall portion 40.

Here, the cross-sectional shape of the rubber wall portion 40 in the axial direction varies depending on the circumferential position.

Specifically, in the rubber wall portion 40, the circumferential middle portion that includes the circumferential center of the liquid chamber 34 and spreads outward at a predetermined angle on both sides in the circumferential direction is formed into a compound curved shape that smoothly connects the inner curved portion 42 that rises from the inner tubular member 12 side toward the outer periphery and then curves axially outward, and the outer curved portion 44 that rises from the outer tubular member side toward the inner periphery and then curves axially inward, with an inflection point. In particular, the compound curved shape in this embodiment is formed in such a way that an intermediate stepped portion 50 that extends in the approximate axial direction (slightly inclined toward the outer periphery as it goes outward in the axial direction) and forms the connection portion of the inner and outer periphery curved portions 42, 44 is provided between the inner curved portion 46 that rises outward in the approximate axial direction from the inner tubular member 12 side in the inner curved portion 42, and the outer curved portion 48 that rises inward in the approximate axial direction from the outer tubular member 14 side (intermediate sleeve 18 side) in the outer curved portion 44.

On the other hand, as shown in Fig. 4, both circumferential end portions of the rubber wall portion 40 have a single curved shape that rises from the inner tube fitting 12 side toward the outer periphery, then curves toward the axially outward and further extends axially outward. In particular, in this embodiment, the single curved shape is a shape in which an inner periphery side rising portion 52 that rises outward in a direction substantially perpendicular to the axis from the inner tube fitting 12 side and an outer periphery side extending portion 54 that extends axially inward from the inner peripheral edge portion (axial inner end edge portion) of the window portion 20 of the intermediate sleeve 18 on the outer tube fitting 14 side are connected by a curved connecting portion 56 in the shape of a substantially quarter-circumference arc.

More specifically, the change in the cross-sectional shape of the rubber wall portion 40 in this embodiment can be seen as a change in the cross-sectional shape of the rubber wall portion 40 when the angle is changed to either side of the circumferential center (vertical line) of the liquid chamber 34 around the central axis in FIG. 1, for example.

That is, on the axial outside of each rubber wall portion 40, an axially outer rubber 58 vulcanized and bonded to the outer peripheral surface of the inner tubular metal fitting 12 is formed by the main rubber elastic body 16, and the axially outer rubber 58 is integrally connected to the axially outer surface of the inner peripheral side rising portion 52 of the rubber wall portion 40. And, in the angle range in which the radial thickness dimension of the axially outer rubber 58 connected to the rubber wall portion 40 is the same as that of the coating rubber layer fixed to the outer peripheral surface of the inner tubular metal fitting 12 (the angle range from the up-down line to slightly exceeding the V-V cross-sectional line on both sides in the circumferential direction), the axial cross-sectional shape of the rubber wall portion 40 does not change from the cross-sectional shape of FIG. 2, which is a composite curved shape having the inner peripheral side rising portion 46, the intermediate step portion 50, and the outer peripheral side rising portion 48. Even after that, the axial cross-sectional shape of the rubber wall portion 40 does not substantially change from the compound curved shape, but as the deflection angle from the circumferential center to the circumferential direction increases, the radial thickness dimension of the axially outer rubber 58 connected to the axially outer surface of the inner circumferential side rising portion 52 of the rubber wall portion 40 gradually increases toward the outer periphery. Then, when the deflection angle from the circumferential center to the circumferential direction becomes even larger and the radial thickness dimension of the axially outer rubber 58 connected to the axially outer surface of the inner circumferential side rising portion 52 of the rubber wall portion 40 becomes even larger, the deformation restraint force acting on the inner circumferential side rising portion 52 of the rubber wall portion 40 by the axially outer rubber 58 becomes large, and the effective free length of the rubber wall portion 40 becomes substantially shorter. However, by changing the axial cross-sectional shape of the rubber wall portion 40 in the region of such a circumferential deflection angle, the deformation restraint by the axially outer rubber 58 is reduced or avoided, and the deformation free length of the rubber wall portion 40 is ensured.

Specifically, as the deflection angle from the circumferential center of the liquid chamber 34 in the circumferential direction becomes larger, the axial cross-sectional shape of the rubber wall portion 40 begins to change the inclination angle of the outer peripheral side rising portion 48, which was facing inward in the axial direction perpendicular to the axis, so that it gradually faces inward in the axial direction, and the inclination angle of the intermediate step-shaped portion 50 gradually increases, and it begins to change to a direction extending directly from the inner peripheral side rising portion 46 toward the radial outward direction. Finally, at both circumferential ends of the rubber wall portion 40 where the deflection angle from the circumferential center of the liquid chamber 34 in the circumferential direction becomes maximum, as shown in FIG. 4, the axial cross-sectional shape of the rubber wall portion 40 becomes a single curved shape in which the outer peripheral side extension portion 54 and the inner peripheral side rising portion 52 are connected by the curved connecting portion 56. It is preferable that such a change in the vertical cross-sectional shape of the rubber wall portion 40 in the circumferential direction around the central axis is a smooth change without a clear break line.

In this way, the rubber wall portion 40, whose cross-sectional shape changes in the circumferential direction, is clearly designed to have a large effective free length by forming a compound curved shape in the circumferential central portion. In addition, since the central portion has a stepped region (intermediate stepped portion 50) that extends in the axial direction, when radial vibration is input, the intermediate stepped portion 50 acts like a piston as the inner and outer tubular members 12, 14 move relative to each other in the direction perpendicular to the axis, and volumetric changes or pressure fluctuations are more efficiently and actively generated in the liquid chamber 34.

In addition, near both circumferential ends of the rubber wall portion 40, the longitudinal section is formed into a single curved shape consisting of the outer peripheral extension portion 54 and the inner peripheral rising portion 52, which reduces or avoids the restraining effect of the axially outer rubber 58 and ensures an effective free length, thereby reducing stress concentration during elastic deformation due to radial vibration input and improving durability.

Incidentally, such an action and effect can also be understood by comparing with a conventional liquid envelope type vibration isolator. As a comparative example, Fig. 21-27 shows a conventional liquid envelope type vibration isolator 60 (integrally vulcanized molded product 62) in which the longitudinal cross-sectional shape of the rubber wall portion 40 is formed with a substantially constant compound curved shape over the entire circumferential direction (a compound curved shape having an inner peripheral side rising portion 46, an intermediate step portion 50, and an outer peripheral side rising portion 48, which has the same basic configuration as the first embodiment). Note that, although the shapes of each part of this comparative example are slightly different from those of the liquid envelope type vibration isolator 10 of the first embodiment because the various characteristics set in this comparative example are different from those of the liquid envelope type vibration isolator 10 of the first embodiment, the basic structure is the same, and in order to make it easier to understand the comparison with the liquid envelope type vibration isolator 10 of the first embodiment, the same reference numerals as those of the liquid envelope type vibration isolator 10 of the first embodiment are used for the parts corresponding to those of the liquid envelope type vibration isolator 10 of the first embodiment in each figure of the comparative example.

In this comparative example, the longitudinal section of the rubber wall portion 40 is a substantially constant compound curved shape over the entire circumferential direction, and as can be seen from Figs. 24-25 and the like, at both circumferential ends of the rubber wall portion 40, the inner circumferential side rising portion 46 and the intermediate step portion 50 of the rubber wall portion 40 are restrained by the rise of the axially outer rubber 58. As a result of the axially outer rubber 58 connecting to the inner circumferential portion of the rubber wall portion 40, the only portion of the rubber wall portion 40 that is relatively easily allowed to undergo elastic deformation is the outer circumferential side rising portion 48 that is left on the outer circumferential side of the rubber wall portion 40 and rises in the axis-perpendicular direction. Therefore, at both circumferential ends of the rubber wall portion 40, it is inevitable that the effective free length of the rubber wall portion 40 becomes significantly smaller, and since the remaining outer circumferential side rising portion 48 is substantially compressed/tensile deformed in the vibration input direction perpendicular to the axis, it can be understood that stress concentration is likely to occur during vibration input, which is the main cause of cracks and the like.

Furthermore, in the liquid envelope type vibration isolator 10 of this embodiment in which the rubber wall portion 40 is set to have a different shape in the circumferential direction as described above, a continuous curved portion 66 is formed at the approximate connection portion of the rubber wall portion 40 with the axially outer rubber 58, and is concave toward the axially outward direction so as to extend approximately along the outer peripheral surface of the inner tube metal fitting 12 and the circumferential end portions of the pair of connecting rubber arm portions 28, 28. In other words, the continuous curved portion 66 extends from the inner peripheral edge portion along the outer peripheral surface of the inner tube metal fitting 12 to the circumferential end portions of the pair of connecting rubber arm portions 28, 28 toward the outer tube metal fitting 14 side in the rubber wall portion 40. By forming this continuous curved portion 66, the rubber wall portion 40 has a large degree of deformation freedom and is easily deformed, and the deformation restraining force by the axially outer rubber 58 and the connecting rubber arm portion 28 is reduced. As a result, stress concentration near the boundary portion of the rubber wall portion 40 with the axially outer rubber 58 and the connecting rubber arm portion 28 is reduced, and a decrease in durability due to the occurrence of cracks is more effectively prevented.

Incidentally, the improvement in durability due to the rubber wall portion 40 having the above-mentioned specific structure has also been confirmed by the inventors from the results of stress distribution analysis by simulation. In addition, the improvement in durability due to the rubber wall portion 40 having the above-mentioned specific structure can be confirmed and understood by checking the shape of the rubber wall portion 40 in the up-down direction, which is the vibration input direction, for example.

That is, since the main vibration input direction in the liquid envelope type vibration isolator 10 of this embodiment is the vertical direction, when vibration is input, the inner and outer tubular metal fittings 12, 14 are displaced relative to each other in the vertical direction, and the vibration load on the main rubber elastic body 16 is applied in the vertical direction. Therefore, when considering the effective free length of the rubber wall portion 40 in the vertical direction in FIG. 1, it is clear from FIG. 1 that the effective free length is longest at the center in the horizontal direction and smallest near both ends in the circumferential direction. Therefore, the longitudinal cross-sectional shape of the rubber wall portion 40 near both left and right ends of the liquid chamber 34 is shown in FIG. 6 as the VI-VI cross-section in FIG. 1. As can be seen from FIG. 6, even near both left and right ends, the rubber wall portion 40 firmly maintains a composite curved shape having the inner peripheral side rising portion 46, the intermediate step portion 50, and the outer peripheral side rising portion 48 in the vertical direction, which is the main vibration input direction. As a result, the rubber wall portion 40 maintains an advantageous compound curved shape in the vertical direction, which is the main vibration input direction, over the entire length of the rubber wall portion 40 in the horizontal direction, i.e., over the entire liquid chamber 34, and it can be seen that excellent liquid chamber change amount and durability can be effectively achieved at the same time.

Although the first embodiment of the present invention has been described above, the present invention is not limited to the specific description or structure of the first embodiment. For example, the specific shape of the main rubber elastic body 16, and thus the specific shapes of the two liquid chambers 34, 34, the pair of connecting rubber arm portions 28, 28, the axially outer rubber 58, 58, etc., and the orifice passage 36, etc., are set appropriately according to the load characteristics and vibration isolation characteristics required of the liquid envelope type vibration isolation device, and are not limited thereto.

As for a liquid envelope type vibration isolating device in which the specific shape of the main rubber elastic body 16 is different, a liquid envelope type vibration isolating device 10' as a second embodiment is shown in Figure 8-14, and a liquid envelope type vibration isolating device 10" as a third embodiment is shown in Figure 15-20. Note that in Figures 8-14 and 15-20, components and parts that have the same structure as the liquid envelope type vibration isolating device 10 of the first embodiment are given the same reference numerals as in the first embodiment, and detailed explanations are omitted.

In other words, the liquid envelope type vibration isolator 10' as the second embodiment and the liquid envelope type vibration isolator 10'' as the third embodiment are both examples of devices in which the characteristics are set differently by changing the shape of the continuous curved portion 66 in the rubber wall portion 40 of each liquid chamber 34 compared to the liquid envelope type vibration isolator 10 of the first embodiment.

Specifically, in the second embodiment of the liquid envelope type vibration isolator 10', as can be seen by comparing FIG. 1 of the first embodiment of the liquid envelope type vibration isolator 10 with FIG. 8 of the second embodiment of the liquid envelope type vibration isolator 10', in the first embodiment of the liquid envelope type vibration isolator 10, the continuous curved portion 66 at both circumferential ends of the rubber wall portion 40 extends linearly from the inner tube metal fitting 12 to the intermediate sleeve 18 at the circumferential end of the connecting rubber arm portion 28 in the left-right direction in the figure.

On the other hand, in the second embodiment of the liquid envelope type vibration isolator 10', at both circumferential ends of the rubber wall portion 40, the continuous curved portion 66 extends in the left-right direction in a curved shape that rises obliquely upward (or downward) in an arc shape from the inner tube metal fitting 12 toward the intermediate sleeve 18, so as to follow the circumferential end face (see FIG. 14) of the connecting rubber arm portion 28. Note that in both the first and second embodiments of the liquid envelope type vibration isolator 10, 10', the liquid chambers 34, 34 including the rubber wall portions 40, 40 on both axial sides are symmetrical to each other in the vertical axis-perpendicular direction, and the liquid envelope type vibration isolator 10, 10' as a whole is also symmetrical to each other in the vertical axis-perpendicular direction.

In addition, in the third embodiment of the liquid envelope type vibration isolator 10'', as can be seen by comparing FIG. 1 of the first embodiment of the liquid envelope type vibration isolator 10 with FIG. 15 of the third embodiment of the liquid envelope type vibration isolator 10'', in the first embodiment of the liquid envelope type vibration isolator 10, the upper and lower liquid chambers 34, 34 are symmetrical in shape, including the rubber wall portions 40, 40 on both sides in the axial direction, whereas in the third embodiment of the liquid envelope type vibration isolator 10'', the rubber wall portions 40, 40 of the upper liquid chamber 34 and the rubber wall portions 40, 40 of the lower liquid chamber 34 are different from each other, particularly with respect to the shape of the continuous curved portion 66, and are therefore asymmetrical.

Specifically, the continuous curved portion 66 of the lower rubber wall portion 40 has a shape of the continuous curved portion 66 that is substantially the same as that of the liquid-sealed type vibration-damping device 10' of the second embodiment, while the continuous curved portion 66 of the upper rubber wall portion 40 extends diagonally downward from the inner tube metal fitting 12 toward the intermediate sleeve 18 in a straight line in the left-right direction at both circumferential ends of the rubber wall portion 40, from the circumferential end face of the connecting rubber arm portion 28 (see FIG. 14) toward the further downward (the axial outer surface of the connecting rubber arm portion 28). Note that, as shown in FIG. 15, in the appearance of the liquid-sealed type vibration-damping device 10'' of this embodiment from the axial front, the continuous curved portion 66 of the upper rubber wall portion 40 and the continuous curved portion 66 of the lower rubber wall portion 40 are vertically spaced apart from each other at both circumferential ends of the rubber wall portion 40, and extend diagonally downward from the inner tube metal fitting 12 toward the intermediate sleeve 18 on both the left and right sides.

In these second and third embodiments of the liquid envelope type vibration isolator 10', 10" as well, the vertical cross-sectional shape of each rubber wall portion 40 changes in the circumferential direction as in the first embodiment, with a compound curved shape in the circumferential central portion and a single curved shape at both circumferential ends. In this way, even in the liquid envelope type vibration isolator 10', 10" of each embodiment that employs the same rubber wall portion 40 as in the first embodiment, as in the liquid envelope type vibration isolator 10 of the first embodiment, when vibration is input in the axis-perpendicular direction between the inner and outer cylindrical fittings 12, 14, pressure fluctuations are efficiently generated in the liquid chamber 34, ensuring the amount of fluid flow through the orifice passage 36 and providing good vibration isolating performance, and the effective free length of the rubber wall portion 40 near both circumferential ends of the liquid chamber 34 is ensured, enabling good durability to be achieved, thus achieving the technical effects of the present invention.

Although the embodiments of the present invention have been described in detail above, the present invention is not to be interpreted in a limited manner based on the above specific description. For example, the specific shapes and sizes of the inner and outer tubular metal fittings 12, 14, main rubber elastic body 16, orifice passage 36, connecting rubber arm portion 28, etc. can be appropriately changed depending on the object to which the liquid envelope type vibration isolation device is attached and the required load characteristics and vibration isolation characteristics.

In addition, in the above embodiment, the inner tube metal fitting 12 and the outer tube metal fitting 14 are arranged on approximately the same central axis, but they can also be arranged eccentrically with respect to each other, and further, the elastic main axes of the pair of connecting rubber arm portions 28, 28 can be inclined in the circumferential direction around the central axis of the inner tube metal fitting 12 so as to extend radially at a predetermined crossing angle other than 180 degrees. Such an embodiment can be preferably adopted, for example, when the liquid-sealed type vibration-proof device of the present invention is applied to an engine mount, in which a preload such as the weight of a power unit is applied in one direction perpendicular to the axis, and it is possible to further improve durability by reducing or avoiding the generation of tensile stress in the connecting rubber arm portions 28, 28 and the rubber wall portion 40.

Furthermore, the specific dimensions and shapes of the pair of connecting rubber arms 28, 28 are not limited. For example, in the above embodiment, the circumferential end faces of the pair of connecting rubber arms 28, 28 each extend in a substantially radial direction, so that the circumferential thickness dimension of the connecting rubber arm 28 gradually increases from the inner circumference side to the outer circumference side (see FIG. 7, etc.). However, it is also possible to adopt a connecting rubber arm 28 in which both circumferential end faces are substantially parallel and extend from the inner circumference side to the outer circumference side with a substantially constant thickness dimension, as in the comparative example (see FIG. 27).

In addition, in the above embodiment, a specific cross-sectional shape that differs in the circumferential direction according to the present invention is adopted for all of the rubber wall portions 40, 40 of the two liquid chambers 34, 34. However, taking into consideration, for example, the input load, the magnitude and direction of vibration, and the required durability and vibration-proofing performance, it is also possible to adopt a specific cross-sectional shape that differs in the circumferential direction according to the present invention for only the rubber wall portions 40, 40 of one of the liquid chambers 34.

The inner peripheral rising portion 46 and the outer peripheral rising portion 48 of the rubber wall portion 40 are not limited to being perpendicular to the inner tube metal fitting 12, and may be slightly inclined in the axial direction, and the inclination angle of the intermediate step portion 50 is also greater in the axial direction than the inner peripheral rising portion 46 and the outer peripheral rising portion 48, but is not specifically limited. Furthermore, the specific dimensions such as length of the inner peripheral rising portion 46, the outer peripheral rising portion 48, and the intermediate step portion 50 can be set appropriately according to the required characteristics, etc., and are not specifically limited.

Although we will not list them all here, the present invention can be embodied in various forms that include changes, modifications, improvements, etc. based on the knowledge of those skilled in the art, and it goes without saying that all such embodiments are included within the scope of the present invention as long as they do not deviate from the spirit of the present invention.

10 Liquid envelope type vibration isolation device (first embodiment)
10' Liquid envelope type vibration isolator (second embodiment)
10" Liquid envelope type vibration isolation device (third embodiment)
12 Inner cylindrical metal member 14 Outer cylindrical metal member 16 Main rubber elastic body 18 Intermediate sleeve 20 Window portion 22 Circumferential groove 24 Integral vulcanization molded product (first embodiment)
24' Integral vulcanization molded product (second embodiment)
24" integral vulcanization molded product (third embodiment)
26 Pocket portion 28 Connecting rubber arm portion 29 Cushioning rubber protrusion 30 Orifice forming rubber 32 Orifice groove 34 Liquid chamber 36 Orifice passage 40 Rubber wall portion 42 Inner circumference curved portion 44 Outer circumference curved portion 46 Inner circumference rising portion 48 Outer circumference rising portion 50 Intermediate step portion 52 Inner circumference rising portion 54 Outer circumference extending portion 56 Curved connecting portion 58 Axial outer rubber 60 Liquid envelope type vibration isolator (Comparative example)
62 Integral vulcanization molding (Comparative example)
66 Continuous curved section

Claims (5)

A liquid-sealed vibration-proof device in which an inner shaft member and an outer cylindrical member are connected by a main rubber elastic body, and two liquid chambers are formed on both sides of the inner shaft member in a direction perpendicular to the axis thereof and are mutually communicated with each other through an orifice passage,
the axial cross-sectional shapes of the rubber wall portions constituting the wall portions on both axial sides of the liquid chamber in the main rubber elastic body are different between a central portion and both end portions in the circumferential direction of the liquid chamber,
The central portion has a compound curved shape in which an inner circumferential side curved portion that rises from the inner shaft member side toward the outer circumferential side and then curves axially outwardly and an outer circumferential side curved portion that rises from the outer tubular member side toward the inner circumferential side and then curves axially inwardly are smoothly connected,
A liquid envelope type vibration isolation device characterized in that both end portions rise from the inner shaft member side toward the outer periphery, then curve axially outward and further extend axially outward, forming a single curved shape. The main rubber elastic body has a pair of connecting arms extending in an axially perpendicular direction between the inner shaft member and the outer cylindrical member between both circumferential ends of the two liquid chambers, and the two liquid chambers are formed between both circumferential ends of the pair of connecting rubber arms.
A liquid envelope type vibration isolation device as described in claim 1, wherein each rubber wall portion of the liquid chamber has a continuous curved portion that is concave axially outward, from the inner peripheral edge portion along the outer peripheral surface of the inner shaft member, and extends the circumferential ends of the pair of connecting arms toward the outer cylindrical member. A liquid envelope type vibration isolation device according to claim 1 or 2, in which the two liquid chambers, including the rubber wall portions, are symmetrical in the radial direction sandwiching the inner shaft member. The pair of connecting rubber arm portions are provided on a line perpendicular to the axis of the inner shaft member, and the circumferential sizes of the two liquid chambers are the same.
A liquid envelope type vibration isolation device as described in claim 2, wherein the continuous curved portion provided in the rubber wall portion between the two liquid chambers has different directions and lengths extending from the inner shaft member side toward the outer cylindrical member side at both longitudinal sides. An intermediate sleeve is fixed to the outer periphery of the main rubber elastic body,
The main rubber elastic body is provided with two pockets, each of which opens to an outer circumferential surface through a window provided in the intermediate sleeve,
An outer peripheral end of the rubber wall portion is fixed to an axial end edge of the window portion of the intermediate sleeve, and the rubber wall portion is provided between the inner shaft member and the intermediate sleeve,
A liquid envelope type vibration isolation device as described in claim 1 or 2, wherein the outer cylindrical member is inserted and fixed onto the intermediate sleeve, and the window portion of the intermediate sleeve is covered by the outer cylindrical member, thereby forming the two liquid chambers.

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