JP5606892B2 - Vibration isolator - Google Patents

Description

  The present invention relates to a vibration isolator, and more particularly to a vibration isolator capable of reducing a dynamic spring constant in a high frequency range.

  Conventionally, as an anti-vibration device such as an engine mount that supports the vibration of a vibration source such as an automobile engine so as not to be transmitted to the vehicle body side, a cylindrical first mounting tool and a first fitting disposed above the shaft core portion are used. A substantially conical anti-vibration device comprising two attachments and an anti-vibration base that is interposed between the two attachments and has a tapered wall shape with a small diameter from the first attachment to the second attachment; Are known. Such a conical vibration isolator generally has a first enclosure and a second liquid chamber formed by attaching a diaphragm to a first fixture to form a liquid enclosure chamber with the anti-vibration base. The liquid chamber is configured as a liquid-filled vibration isolator by partitioning the two liquid chambers through an orifice channel. The vibration damping function and the vibration insulation function are achieved by the liquid column resonance effect caused by the liquid flow in the orifice flow path and the vibration damping effect of the vibration isolation base.

  In such a conventional vibration isolator, even for the purpose of reducing vibrations in the high frequency range, vibrations up to 1 kHz are targeted, and the dynamic spring constant in the high frequency range of 1 kHz or higher is reduced. It was not something that could be done.

  For example, in Patent Document 1 below, a thin wall portion is formed by a concave portion on the inner peripheral surface of a vibration-damping base having a tapered wall shape, and the vibration is caused by membrane resonance at the thin wall portion with respect to vibration input in the middle frequency range of 100 to 500 Hz. A minimum value is given to the spring characteristics, and for a vibration input in the high frequency range of 500 to 1000 Hz, a minimum value is set for the dynamic spring constant by an intermediate-frequency device made of an umbrella-shaped metal member provided in the main liquid chamber. A configuration is provided that is provided. Similarly, Patent Document 2 below discloses that a thin portion and a thick portion are provided by providing a concave portion on the inner peripheral surface side of a vibration-proof base having a tapered wall shape. However, in these documents, attention is paid to the film resonance, which is a resonance phenomenon as an elastic film that occurs when the thin wall portion of the vibration-proof substrate is elastically deformed with a spring property due to the liquid flow in the liquid chamber. Resonance is not disclosed. That is, in the high frequency range of 1 kHz or higher, liquid flow no longer substantially occurs, and the increase of the dynamic spring constant due to resonance of the vibration isolating base itself is dominant, but the resonance phenomenon of the vibration isolating base itself is controlled. There is no disclosure about what to do.

  In Patent Document 3 below, a conical mount portion provided with an elastic main body that performs membrane resonance and a cylindrical bush portion provided with an end wall and elastic partition wall that perform membrane resonance are integrated, and resonance by both membrane resonances occurs. It is disclosed that the dynamic spring constant is reduced by coupling characteristics. Also in this document, the dynamic spring constant is reduced by membrane resonance, and the frequency is also in the frequency range of 200 to 1000 Hz, and the resonance phenomenon of the vibration-proof base itself in the higher frequency range is controlled. Is not disclosed.

JP 10-339348 A JP 2008-232364 A JP 2002-310222 A

  In recent years, with motors becoming quieter, and especially motor-driven vehicles that have been developed recently, it may be required to reduce the dynamic spring constant in a high frequency range of about 1 kHz or more. As described above, it is difficult for the conventional vibration isolator to sufficiently satisfy such a demand.

  This invention is made | formed in view of the above point, and it aims at providing the vibration isolator which can reduce the dynamic spring constant in a high frequency range.

The vibration isolator according to the present invention includes a cylindrical first fixture that is attached to one of the vibration source side and the support side, and a vibration source side and a support side that are disposed on the shaft core portion of the first fixture. A second fixture attached to the other, and a vibration isolating base made of a rubber-like elastic material interposed between the first fixture and the second fixture. In the vibration isolator formed on the tapered wall portion that decreases in diameter from the first fixture toward the second fixture, the tapered wall portion changes the thickness in the circumferential direction, It is formed in a thin portion, and the thick portion is thickened mainly on the second fixture side in the axial direction on the inner surface side of the tapered wall portion with respect to the thin portion, and the outer surface side of the tapered wall portion. in a shape that the thickness increase of the first fixture side in mainly axial direction, with respect to the axis of the first fixture The inclination angle of KiAtsu meat portion is one that is set smaller than the inclination angle of the thin portion with respect to said axis.

  In a preferred aspect of the present invention, the thickness of the thick part is formed to be greater than the thickness of the thin part, and the length along the inclination direction of the thick part is the length along the inclination direction of the thin part. The cross-sectional area of the thick part may be set larger than the cross-sectional area of the thin part in the cross section including the shaft core. In another preferred embodiment, the thick part and the thin part may be provided at positions symmetrical with respect to the axis in the circumferential direction. In still another preferred embodiment, the formation range in the circumferential direction of the thick portion may be set larger than the formation range in the circumferential direction of the thin portion. Alternatively, the formation range in the circumferential direction of the thick portion may be set smaller than the formation range in the circumferential direction of the thin portion. In another preferred embodiment, the peak of the dynamic spring constant in the resonance characteristic of the thick part and the bottom of the dynamic spring constant in the resonance characteristic of the thin part interfere with each other in a frequency range of 500 Hz or more. The resonance characteristic by the thick part and the resonance characteristic by the thin part may be coupled. In still another preferred embodiment, a diaphragm made of a rubber-like elastic film that is attached to the first fixture and forms a liquid sealing chamber with the vibration isolating substrate; and the liquid sealing chamber on the vibration isolating substrate side You may provide the partition body divided into the 1st liquid chamber and the 2nd liquid chamber on the said diaphragm side, and the orifice flow path which connects the said 1st liquid chamber and a 2nd liquid chamber.

  In the vibration isolator according to the present invention, the thick wall portion and the thin wall portion are provided on the tapered wall portion of the vibration isolating substrate, and the inclination angle of both is set as described above, so that the vibration isolating substrate itself resonates. It is possible to effectively reduce the dynamic spring constant in the high frequency range where the is dominant.

It is a longitudinal cross-sectional view (II sectional view taken on the line of FIG. 2) of the vibration isolator which concerns on embodiment. It is a horizontal sectional view (II-II line sectional view of Drawing 1) of the vibration isolator. It is sectional drawing which shows the structure around the vibration proofing base | substrate of the vibration isolator which concerns on a comparative example. It is a graph which shows the dynamic spring characteristic of the vibration isolator which concerns on a comparative example. It is explanatory drawing which shows the resonance mode of the vibration isolator base | substrate in each frequency range. It is a graph which shows the change of the dynamic spring characteristic by the thickness of a vibration proof base. It is a figure for demonstrating the motion of the vibration isolator base | substrate with respect to the displacement of a 2nd fixture. It is a graph which shows the change of the dynamic spring characteristic by the length of a vibration proof base. It is a graph which shows the dynamic spring characteristic which concerns on embodiment.

  Hereinafter, a vibration isolator 10 according to an embodiment of the present invention will be described with reference to the drawings.

  1 and 2 show a vibration isolator 10 according to an embodiment. The vibration isolator 10 is a mount that is interposed between a vibration source such as an automobile engine or motor and a support side such as a vehicle body frame and supports the vibration source in an anti-vibration manner, and is attached to the support side. A lower cylindrical first fixture 12, an upper second fixture 14 attached to the vibration source side, and a rubber-like elastic material interposed between the fixtures 12, 14. And a base 16. In this example, the vibration isolator 10 further includes a diaphragm 18 made of a rubber-like elastic film attached to the first fixture 12, and between the vibration isolator base 10 and the diaphragm 18 inside the first fixture 12. A formed liquid enclosure chamber 20, a partition 22 that divides the liquid enclosure chamber 20 into an upper first liquid chamber 20A and a lower second liquid chamber 20B, a first liquid chamber 20A, and a second liquid chamber 20B; Therefore, the vibration isolator 10 is a so-called conical liquid-filled vibration isolator.

  The first fixture 12 is a cylindrical main body bracket in which the vibration-proof base 16 is vulcanized and bonded to the inner peripheral surface. In this example, the first fixture 12 includes an upper-side large-diameter cylindrical portion 12A and a lower-side small-diameter cylindrical portion 12C whose diameter is set small via a tapered cylindrical portion 12B. The first fixture 12 is configured to be attached to the vehicle body via a bracket (not shown) or the like.

  The second fixture 14 is a boss fitting disposed above the axial center portion of the first fixture 12, that is, on the axial center O of the first fixture 12 in the axial direction Z from the first fixture 12. It is arranged above a predetermined distance. The second fixture 14 is interposed via the vibration isolation base 16 so that the axial direction Z (that is, the vertical direction) of the first fixture 12 is the main load direction (that is, the main load input direction) of the vibration isolation device 10. The first fixture 12 is connected. A stopper portion 26 is formed on the peripheral surface of the second fixture 14 so as to protrude outward in the radial direction in a flange shape. Further, a female screw portion 28 is provided on the upper surface, and a bolt (not shown) is screwed to the upper surface to be attached to a member of a vibration source.

  The anti-vibration base 16 has a tapered wall shape (which can also be referred to as a truncated cone shape or a substantially umbrella shape) gradually decreasing in diameter from the first fixture 12 toward the second fixture 14, that is, the second fixture. A tapered wall portion 30 having a small diameter toward the fixture 14 is provided over the entire circumference, and the first fixture 12 and the second fixture 14 are connected via the tapered wall portion 30. The anti-vibration base 16 is vulcanized and bonded at its lower end to the upper end opening of the first fixture 12 (ie, the large diameter cylindrical portion 12A) and at its upper end to the lower portion of the second fixture 14. The upper end portion covers the entire convex portion 14A and covers the stopper portion 26 so that the convex portion 14A protruding downward from the stopper portion 26 of the second fixture 14 is embedded. The stopper rubber portion 32 is continuous. A rubber film-like seal wall portion 34 covering the inner peripheral surface of the first fixture 12 is connected to the lower end portion of the vibration isolation base 16.

  The diaphragm 18 is a flexible rubber film that is disposed opposite to the vibration isolating base 16 in the axial direction Z and forms a liquid sealing chamber 20 with the inner surface of the vibration isolating base 16. A reinforcing metal fitting 19 is provided, and is fixed by caulking to the caulking portion 35 at the lower end of the first fixture 12 through the reinforcing metal fitting 19. A liquid such as water, ethylene glycol, or silicone oil is sealed in the liquid sealing chamber 20. The liquid enclosure 20 is divided into a first liquid chamber (main liquid chamber) 20A in which the vibration isolation base 16 forms part of the chamber wall and a second liquid chamber (in which the diaphragm 18 forms part of the chamber wall). The first liquid chamber 20A and the second liquid chamber 20B are communicated with each other via an orifice channel 24 as a throttle channel.

  The partition body 22 includes an annular orifice forming member 36 provided inside the small-diameter cylindrical portion 12C of the first fixture 12 and an outer peripheral portion vulcanized and bonded to the inner peripheral surface of the orifice forming member 36. It consists of an elastic wall 38 made of a rubber elastic body that closes between the surfaces, and a pair of upper and lower partition plates 40 and 42 that sandwich the elastic wall 38 in the axial direction Z.

  The orifice forming member 36 is a rigid member that forms the orifice channel 24 extending in the circumferential direction C between the inner peripheral surface of the first fixture 12 and is fitted to the seal wall 34. The pair of partition plates 40 and 42 are connected to each other via a columnar connecting portion 44 that penetrates the central portion in the radial direction of the elastic wall 38 having a circular shape in plan view. Among them, the upper partition plate 40 constitutes a part of the chamber wall of the first liquid chamber 20A, and the lower partition plate 42 constitutes a part of the chamber wall of the second liquid chamber 20B. The displacement amount in the axial direction Z of the pair of partition plates 40 and 42 is configured to be regulated by the elastic wall 38. Further, the elastic wall 38 is provided with a through hole 46, and the first liquid chamber 20 </ b> A and the second liquid chamber 20 </ b> B are connected via the through hole 46 at a neutral position of the pair of partition plates 40 and 42 so that the liquid can flow. In addition, the through hole 46 is configured to be closed by the partition plates 40 and 42 due to the displacement of the pair of partition plates 40 and 42 in the axial direction Z.

  Thereby, for large amplitude vibrations in a low frequency range, the displacement amount of the pair of partition plates 40 and 42 is restricted by the elastic wall 38 and the through hole 46 is closed by the partition plates 40 and 42. Thus, high attenuation performance can be ensured by the liquid flow effect by the orifice channel 24. In addition, for fine amplitude vibration in a higher frequency region (but lower than 1000 Hz), the dynamic spring constant is reduced by reciprocating the pair of partition plates 40 and 42. Can do. At this time, since both liquid chambers 20A and 20B are connected to each other through the through hole 46 so that the liquid can flow, this portion can act as a high-frequency orifice, and the resonant action of the flowing liquid can be achieved. Based on this, a low dynamic spring effect can be exhibited.

  In this embodiment, in the present embodiment, the thick wall portions 48 and the thin wall portions 50 are alternately provided in the circumferential direction C on the tapered wall portion 30 of the vibration-isolating base 16, and different frequency characteristics are obtained in the respective shapes. By providing it, the dynamic spring constant in the high frequency region is reduced. That is, the tapered wall portion 30 is formed in the thick portion 48 and the thin portion 50 by changing the thickness in the circumferential direction C, and the inclination angle θ1 of the thick portion 48 with respect to the axis O is a thin portion. It is set smaller than the inclination angle θ2 of 50 (θ1 <θ2).

  Specifically, each of the thick portion 48 and the thin portion 50 is formed over the entire axial direction Z of the tapered wall portion 30, and the thickness T 1 of the thick portion 48 is larger than the thickness T 2 of the thin portion 50. It is set large (T1> T2). Further, the length L1 along the inclination direction of the thick portion 48 is set to be larger than the length L2 along the inclination direction of the thin portion 50 (L1> L2). Thereby, in the cross section including the axis O shown in FIG. 1, the cross sectional area (S1) of the thick part 48 is larger than the cross sectional area (S2) of the thin part 50 (S1> S2).

  Here, the thicknesses T1 and T2 of the thick portion 48 and the thin portion 50 are average thicknesses from the upper end to the lower end, respectively. In addition, the inclination angles θ <b> 1 and θ <b> 2 of the thick portion 48 and the thin portion 50 are angles formed by a line passing through the approximate center in the thickness direction of the tapered wall portion 30 with respect to the axis O. Moreover, the length along the inclination direction of the thick part 48 and the thin part 50 is the length along the inclination direction of the range in which the respective resonance modes appear. Therefore, the length L1 of the thick part 48 is the axial center. It is the length in the direction inclined by θ1 with respect to O, and the length L2 of the thin portion 50 is the length in the direction inclined by θ2 with respect to the axis O (see FIG. 1).

  In general, the longer the inclination angle of the tapered wall portion 30 is, the more the shape of the tapered wall portion 30 is laid down, the longer the length of the tapered wall portion 30 is due to the radial difference between the first fixture 12 and the second fixture 14. Since it tends to approach, the length along the inclination direction becomes shorter. For this reason, the thick portion 48 has a shape caused by reducing the inclination angle θ1, so that the length L1 along the inclination direction is long, and the thin portion 50 has a shape in which the inclination angle θ2 is increased and laid down. As a result, the length L2 along the tilt direction is shortened.

  As shown in the right half sectional view of FIG. 1, the thick portion 48 is thickened mainly on the lower side on the inner peripheral side (liquid sealing chamber 20 side) with respect to the thin portion 50, and the outer peripheral side (outside air side). ) Mainly has a shape with an increased thickness on the upper side, whereby the thickness (T1> T2), the inclination angle (θ1 <θ2), the length (L1> L2), and the cross-sectional area (S1> S2). ) Is set.

  In plan view of the vibration-proof base 16, as shown in FIG. 2, a plurality of thick portions 48 and thin portions 50 are provided at positions symmetrical to the axis O. Specifically, in this example, thick portions 48 are provided symmetrically at two locations facing the first radial direction X across the axis O, and between these two thick portions 48, that is, the first Thin portions 50 are provided symmetrically at two locations facing the second radial direction Y perpendicular to the radial direction X. Further, the formation angle θ3 that is the formation range in the circumferential direction C of the thick portion 48 is set to be the same as the formation angle θ4 that is the formation range in the circumferential direction C of the thin portion 50 (θ3 = θ4).

  By arranging the thick part 48 and the thin part 50 in this way, the spring is high in the X direction where the thick part 48 is opposed, and the spring is low in the Y direction where the thin part 50 is opposed. The spring ratio can be applied. For example, by setting the X direction as the vehicle front-rear direction and the Y direction as the vehicle left-right direction, the front-rear direction spring can be set high and the left-right direction spring can be set low. On the contrary, by setting the X direction as the vehicle left-right direction and the Y direction as the vehicle front-rear direction, the left-right spring may be set higher and the front-rear spring may be set lower.

  By forming the tapered wall portion 30 in the thick portion 48 and the thin portion 50 as described above, the dynamic spring constant can be reduced in a high frequency range where the resonance of the vibration isolating base 16 itself is dominant. The reason will be described in detail.

  As for the anti-vibration device of the comparative example having the anti-vibration base 16 (thickness T, length L) including the thick wall portion 48 and the tapered wall portion 30 without the thin wall portion 50 as shown in FIG. When the dynamic spring characteristics in the high frequency range up to were measured, the dynamic spring characteristics as shown in FIG. 4 were obtained. As shown in the figure, up to 2000 Hz, four peaks of A region, B region, C region and D region were recognized. Among these, in the B region, the C region, and the D region, the reason that the dynamic spring constant has a jumping peak (maximum value) is that the reaction force increases due to the resonance of the vibration-proof base itself as shown in FIG. It turns out that. That is, the peak in the B region of about 600 to 800 Hz is due to the primary mode of resonance of the vibration-proof substrate as shown in FIG. 5A, and the peak in the C region of about 950 to 1250 Hz is As shown in FIG. 5 (b), this is due to the secondary mode of resonance of the vibration-proof substrate, and the peak in the D region of about 1450 to 1850 Hz is 3 of the resonance of the vibration-proof substrate as shown in FIG. This is due to the next mode. Among these, the peaks in the C region and the D region (about 800 Hz to about 2 kHz) are particularly large, and particularly in the high frequency region of 1 kHz or more, the liquid flow no longer substantially occurs in the liquid sealing chamber. Since the increase of the dynamic spring constant due to the resonance of the vibration base itself becomes dominant, it is desired to control the resonance phenomenon of the vibration isolation base.

  Therefore, various studies were made to control the resonance phenomenon of the vibration isolating substrate. By changing the thickness T (volume) of the vibration isolating substrate (tapered wall), the resonance frequency of the vibration isolating substrate changed, It was confirmed that the peak frequency of the dynamic spring constant in each of the above-mentioned areas B to D (frequency when the peak was reached) was changed.

  That is, the peak frequency f of the dynamic spring constant is expressed by f = (1 / 2π) × √ (k / m) using the static spring constant k and the mass m of the vibration-proof base. Here, when the wall thickness T of the vibration-proof substrate increases, the mass m increases, so the peak frequency f decreases. Originally, when the wall thickness T increases, the static spring constant k also increases. However, in the vibration isolator, the static spring constant k is made constant by adjusting the rubber hardness and the like, so the peak frequency f depends only on the mass m. Is done. Also, the resonance level (energy) is small when the rubber volume increases due to the increase in the thickness of the vibration-proof substrate under the condition that the static spring constant is constant, because the rubber hardness needs to be lowered. Become. Accordingly, as shown in FIG. 6, when the thickness T (volume) of the vibration-proof base is increased from the curve (1) indicated by the solid line, the peak frequency of the dynamic spring constant is increased as indicated by the curve (2) indicated by the dotted line. It becomes smaller and the peak size also decreases. That is, the larger the rubber volume, the smaller the peak frequency, and the smaller the rubber volume, the larger the peak frequency.

  On the other hand, it has been found that the magnitude of the peak of the dynamic spring constant due to the resonance of the vibration isolating base itself can be increased or decreased by the inclination angle of the tapered wall portion 30 of the vibration isolating base 16. That is, as shown in FIG. 7A, when the inclination angle θ of the tapered wall portion 30 is largely lying, the tapered wall portion 30 is located above and below the second fixture 14 in the C region and the D region. It moves to repel the movement. In detail, for the movement in which the upper fixture 14 is displaced downward (s), the tapered wall portion 30 is moved obliquely upward (u) on the outer side, and the upper fixture 14 is displaced upward (r). For the movement to be performed, the tapered wall portion 30 moves toward the inside obliquely downward (t). Since it moves so as to repel, the peak of the dynamic spring constant becomes high. Therefore, as shown in FIG. 7B, when the inclination angle θ of the tapered wall portion 30 is reduced, the repulsion of the tapered wall portion 30 can be released in the left-right direction, and the peak of the dynamic spring constant is obtained. It was found that can be reduced.

  Further, when the tapered wall portion 30 is formed in such a shape that the inclination angle θ of the tapered wall portion 30 is reduced as described above, the length L of the tapered wall portion 30 along the inclined direction is long as described above. Therefore, the rubber volume increases accordingly. On the contrary, when the inclination angle θ is increased and the tapered wall portion 30 is laid down, the length L of the tapered wall portion 30 along the inclination direction is shortened, so that the rubber volume is reduced accordingly. Therefore, as shown in FIG. 8, when the tapered wall portion 30 becomes longer from the curve (3) indicated by the solid line, the peak frequency of the dynamic spring constant becomes smaller as indicated by the curve (4) indicated by the dotted line. When the tapered wall portion 30 is shortened, the peak frequency of the dynamic spring constant increases as shown by the curve (5) indicated by the chain line.

  From the above, according to the present embodiment, in the thick portion 48, the cross-sectional area S1 (and hence the rubber volume) is large because the thickness T1 is large and the length L1 is long. Becomes lower. On the other hand, in the thin portion 50, since the cross-sectional area S2 (and hence the rubber volume) is small due to the small thickness T2 and the short length L2, the peak frequency of the dynamic spring constant increases. Therefore, it is possible to disperse the resonance mode frequency of the vibration isolating substrate 16 and to make the two resonance characteristics of the thick portion 48 and the thin portion 50 latent.

  FIG. 9 shows this relationship, and the curve of the embodiment shows the dynamic spring characteristic of the vibration isolator 10 according to the embodiment in which the thick portion 48 and the thin portion 50 are provided. Comparative Example 1 is an example in which the thick wall portion 48 and the thin wall portion 50 are not provided, and the tapered wall portion is formed with a constant intermediate wall thickness over the entire circumference, and Comparative Example 2 is the above thick wall over the entire circumference. This is an example in which the tapered wall portion is formed by the portion 48, and the comparative example 3 is an example in which the tapered wall portion is formed by the thin wall portion 50 over the entire circumference.

  As shown in FIG. 9, in Comparative Example 2, the peak frequency of the dynamic spring constant was decreased by increasing the rubber volume compared to Comparative Example 1. In Comparative Example 3, the peak frequency of the dynamic spring constant was increased by reducing the rubber volume compared to Comparative Example 1. On the other hand, in this embodiment, by providing the thick portion 48 and the thin portion 50 as described above, the peak of the dynamic spring constant is divided into two, and the resonance level is reduced. The reason for this is that in the embodiment, both the thick portion 48 and the thin portion 50 are about half of the comparative example in terms of the rubber volume, so that the resonance energy is also halved by halving the rubber volume. The resonance level of the part 48 and the thin part 50 is considered to be smaller than that of the comparative example. As described above, in this embodiment, the peak frequency of the dynamic spring constant is determined by dividing the peak frequency due to the resonance of the antivibration base 16 into the resonance characteristic due to the thick part 48 and the resonance characteristic due to the thin part 50 having different peak frequencies. Can be reduced in size.

  In addition, according to the present embodiment, the thick wall portion 48 has a shape in which the inclination angle θ1 is reduced and the tapered wall portion 30 is raised, so that the second fixture 14 moves in the left-right direction. You can escape power. Therefore, the peak of the dynamic spring constant in the resonance characteristics due to the thick portion 48 can be reduced. On the other hand, in the thin wall portion 50, the inclination angle θ2 is increased and the tapered wall portion 30 is laid down, so that the repulsive force against the vertical movement of the second fixture 14 increases, but the rubber volume is increased. Since it is small, the repulsive force can be reduced. Therefore, an increase in the peak of the dynamic spring constant in the resonance characteristics due to the thin portion 50 can also be suppressed. Therefore, the dynamic spring constant peak due to the two resonance characteristics can be further reduced.

  In the present embodiment, since the thick portion 48 having a large cross-sectional area (that is, the rubber volume) is further raised, a high static spring constant can be secured in this portion. Since the rubber hardness of the base body 16 can be lowered as compared with the conventional case and the resonance level (energy) can be reduced, the dynamic spring constant peak size can be reduced also in this respect.

  On the other hand, since the thin portion 50 has a laid shape, the input in the axial direction Z mainly becomes a shear input, so that deterioration in durability due to the thinning can be suppressed. Moreover, the problem that the expansion spring increases in the region of 500 Hz or less due to the thick portion 48 and the dynamic spring constant increases due to rebound after liquid resonance can be suppressed by providing the thin portion 50.

  In the present embodiment, in addition to the reduction of the dynamic spring constant due to the dispersion described above, the dynamic spring constant can be further reduced by setting the resonance modes of the thick portion 48 and the thin portion 50 to cancel each other. Have gained. More specifically, as shown in FIG. 9, in the frequency range of 800 Hz or higher, particularly 1000 Hz or higher, the peak (maximum value) of the dynamic spring constant in the resonance characteristics due to the thick portion 48 having a lower peak frequency, and the peak The resonance characteristic by the thick part 48 and the resonance characteristic by the thin part 50 are coupled so that the bottom (minimum value) of the dynamic spring constant in the resonance characteristic by the thin part 50 having a higher frequency interferes with each other. Yes. As a result, the resonance modes of the thin portions 50 located on the high frequency side cancel each other, and the resonance modes of the mutual resonance modes are reversed. Thus, the effect of reducing the larger dynamic spring constant is reduced. can get. In order to say that the two resonance characteristics are coupled as described above, the two peaks of the dynamic spring constant do not appear as independent peaks in each region of C and D, but are shown in FIG. As shown, it is sufficient that two peaks are connected. For this purpose, the cross-sectional areas S1 and S2 (thicknesses T1 and T2 and lengths L1 and L2) between the thick part 48 and the thin part 50 and the dimensional differences such as the inclination angles θ1 and θ2 may be set as appropriate.

  The reduction of the dynamic spring constant by such coupling may be applied in the B region (primary mode). Therefore, in the frequency range of 500 Hz or more, the thick portion 48 so that the peak of the dynamic spring constant in the resonance characteristic of the thick portion 48 and the bottom of the dynamic spring constant in the resonance characteristic of the thin portion 50 interfere with each other. The resonance characteristics due to and the resonance characteristics due to the thin wall portion 50 may be coupled.

  In the present embodiment, the formation range θ3 of the thick portion 48 and the formation range θ4 of the thin portion 50 are set to be equal (θ3 = θ4). However, due to the relationship between these θ3 and θ4, the X direction and the Y direction that are perpendicular to the axis The spring ratio in the direction can be changed. At this time, for example, when the formation range θ3 of the thick portion 48 is set to be larger than the formation range θ4 of the thin portion 50 (θ3> θ4), the formation range of the thick portion 48 having a shape in which the inclination angle θ1 is raised greatly. Therefore, since the force repelling the vertical movement of the second fixture 14 is reduced, an increase in the peak of the dynamic spring constant can be suppressed. On the other hand, when the formation range θ3 of the thick portion 48 is set to be smaller than the formation range θ4 of the thin portion 50 (θ3 <θ4), the formation range of the thin portion 50 becomes large. Since the thin portion 50 has a small expansion spring (spring that pushes out the liquid), the reaction force from the liquid on the liquid sealing chamber 20 side is reduced by increasing this formation region, and the overall spring constant is reduced. Also in this case, an increase in the peak of the dynamic spring constant can be suppressed. As described above, the spring ratio in the X direction and the Y direction can be tuned by the above θ3 and θ4 while suppressing an increase in the peak of the dynamic spring constant. Thus, since the relationship between θ3 and θ4 can be set freely, the spring ratio in the vehicle front-rear direction and the left-right direction can be set freely.

  As described above, according to the present embodiment, the dynamic spring constant is effectively reduced in a high frequency range of 800 Hz or more, more specifically 1000 to 2000 Hz, in which the resonance of the vibration isolating base 16 itself is dominant. Can do. Moreover, in this embodiment, since the said effect is acquired only by the shape of the anti-vibration base | substrate 16, without changing the internal structure of a liquid-filling type anti-vibration apparatus, it does not deteriorate manufacturability, but by low dynamic spring formation. High performance can be realized. Therefore, the high-quality vibration isolator 10 can be obtained at a low cost.

  In the above-described embodiment, the thick portion 48 and the thin portion 50 are provided at two positions on the circumference. However, the arrangement of the thick portion 48 and the thin portion 50 is not limited to this, and various changes can be made. Is possible. For example, the thick portions 48 may be provided at four positions on the circumference at equal intervals, and the thin portions 50 may be provided between the thick portions 48. Moreover, the cross-sectional shape of the thick part 48 and the thin part 50 is only what showed the preferable example, and various changes are possible. Moreover, although the said embodiment demonstrated what the 1st fixture 12 was attached to the support side, and the 2nd fixture 14 was attached to the vibration source side, on the contrary, the 1st fixture 12 is the vibration source side, The second fixture 14 may be attached to the support side. In the above embodiment, the liquid-filled vibration isolator has been described. However, since the present invention is effective in reducing the dynamic spring constant due to the resonance of the vibration isolator base itself, the vibration isolator having no liquid chamber is also used. Can be applied. Although not enumerated one by one, various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 ... Vibration isolator 12 ... 1st fixture 14 ... 2nd fixture 16 ... Anti-vibration base | substrate 20 ... Liquid enclosure 20A ... 1st liquid chamber 20B ... 2nd liquid chamber 22 ... Partition body 24 ... Orifice flow path 30 ... Tapered wall part 48 ... thick part 50 ... thin part T1 ... thick part T2 ... thin part thickness L1 ... thick part length L2 ... thin part length θ1 ... thick part inclination Angle θ2 ... Inclination angle of thin part θ3 ... Formation angle of thick part θ4 ... Formation angle of thin part O ... Shaft core

Claims (7)

A cylindrical first fixture that is attached to either the vibration source side or the support side, and a second that is disposed on the shaft core portion of the first fixture and attached to either the vibration source side or the support side. And a vibration isolating base made of a rubber-like elastic material interposed between the first mounting tool and the second mounting tool, and the vibration isolating base from the first mounting tool to the second mounting tool. In the anti-vibration device formed in the tapered wall portion having a diameter smaller toward the
The tapered wall portion is formed into a thick portion and a thin portion by changing the thickness in the circumferential direction, and the thick portion is mainly on the inner surface side of the tapered wall portion with respect to the thin portion. The thickness of the second fixture side in the axial direction is increased, the outer surface side of the tapered wall portion is mainly thickened on the first fixture side in the axial direction, and the thickness with respect to the axis of the first fixture is increased. An anti-vibration device characterized in that an inclination angle of the meat part is set smaller than an inclination angle of the thin part with respect to the axis.   The thickness of the thick part is formed to be thicker than the thickness of the thin part, and the length along the inclination direction of the thick part is set larger than the length along the inclination direction of the thin part, The vibration isolator according to claim 1, wherein a cross-sectional area of the thick portion is set to be larger than a cross-sectional area of the thin portion in a cross section including the shaft core.   The vibration isolator according to claim 1 or 2, wherein the thick part and the thin part are provided symmetrically with respect to the axis.   The vibration isolator according to any one of claims 1 to 3, wherein a formation range in the circumferential direction of the thick portion is set larger than a formation range in the circumferential direction of the thin portion.   The vibration isolation device according to any one of claims 1 to 3, wherein a formation range in the circumferential direction of the thick portion is set smaller than a formation range in the circumferential direction of the thin portion.   In the frequency range of 500 Hz or more, the resonance characteristics of the thick wall portion so that the peak of the dynamic spring constant in the resonance characteristic of the thick wall portion and the bottom of the dynamic spring constant in the resonance property of the thin wall portion interfere with each other. The vibration isolator according to any one of claims 1 to 5, wherein resonance characteristics by the thin wall portion are coupled.   A diaphragm made of a rubber-like elastic film that is attached to the first fixture and forms a liquid sealing chamber between the vibration isolating base and the first liquid chamber on the side of the vibration isolating base and the diaphragm. The barrier according to any one of claims 1 to 6, further comprising: a partition that partitions the second liquid chamber on the side, and an orifice channel that communicates the first liquid chamber and the second liquid chamber. Shaker.

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