JP5693386B2 - Vibration isolator - Google Patents

Description

  The present invention provides a rubber member having respective rubber leg portions for connecting the outer and inner cylinders at two locations in the circumferential direction between the outer cylinder and the inner cylinder arranged inside the outer cylinder. This is related to a so-called “C” -shaped vibration isolator, and particularly to a vibration isolator suitable for use as an engine mount or a motor mount, and in particular, when using the apparatus, the outer cylinder and the inner cylinder The present invention proposes a technique that effectively suppresses a so-called surging phenomenon that may occur in a rubber member disposed between them, and allows the apparatus to always exhibit the anti-vibration function as expected.

  For example, in this type of vibration isolator that may be used by attaching an outer cylinder and an inner cylinder to each of an engine side member and a vehicle body side member, input vibration from the engine side member is not received. A spring-mass in which each rubber leg part connecting the outer cylinder and the inner cylinder made of a rigid material is used as a spring and a mass for absorbing the elastic member mainly by elastic deformation of two rubber leg parts. In the system, when a vibration having a natural vibration frequency, for example, a frequency around 1000 Hz is input, each rubber leg portion self-excites and the amplitude increases rapidly, resulting in so-called surging. A phenomenon may occur, and the device may not be able to perform the anti-vibration function as expected.

In order to cope with such a surging phenomenon, in Patent Document 1, “a first mounting member attached to one member to be vibration-isolated and a second attachment member attached to the other member to be anti-vibrated and connected” is disclosed. Are spaced apart from each other, and the first attachment member and the second attachment member are elastically connected by the main rubber elastic body, and are separated from both the first attachment member and the second attachment member. A hollow cylindrical housing member is fixed to the main rubber elastic body at the position, and the cylindrical housing member is displaced along with elastic deformation of the main rubber elastic body. An independent mass member is accommodated and disposed, and the independent mass member jumps with respect to the cylindrical housing member due to the displacement of the cylindrical housing member accompanying the deformation of the main rubber elastic body at the time of vibration input. In the vibration isolator configured to repeatedly strike, a peripheral wall portion against which the independent mass member abuts is formed integrally with a housing main body having an opening at at least one axial end portion. The cylindrical housing member is configured by assembling and covering the lid, and the outer peripheral surface of the housing main body is vulcanized and bonded to the rubber elastic body of the main body, and the housing member and the lid An anti-vibration device is proposed in which the butted portion on the outer peripheral surface is covered and sealed with the main rubber elastic body in close contact over the entire circumference.
According to this vibration isolator, “the cylindrical housing member is displaced along with the elastic deformation of the main rubber elastic body, and the independent mass member that jumps in the cylindrical housing member is separated from the cylindrical housing member. Based on the contact of the independent mass member against the cylindrical housing member, an effective vibration damping action is exerted on the main rubber elastic body, and as a result, against the surging that is a problem in the main rubber elastic body. Effective suppression effect is demonstrated. "

JP 2007-270925 A

By the way, in the vibration isolator described in Patent Document 1, since the “independent mass member” made of a metal material or the like and having a large specific gravity is provided in the “main rubber elastic body”, the weight of the entire device increases. When used as an engine mount or a motor mount, there is a problem in that the fuel consumption of the vehicle is reduced.
Further, in this vibration isolator, the hitting sound generated when the “independent mass member” hits the “housing member” may deteriorate the silent performance of the vehicle, etc. There is also a problem that the manufacturing cost increases due to an increase in the number of members accompanying the arrangement of the “housing member”.

  The object of the present invention is to solve such problems of the prior art, and the object of the present invention is to increase the weight of the apparatus and reduce the quiet performance while keeping the manufacturing cost relatively low. Accordingly, it is an object of the present invention to provide a vibration isolator capable of effectively preventing the occurrence of a surging phenomenon and constantly exhibiting the anti-vibration performance as expected without incurring deterioration of the above.

The inventor conducted a numerical analysis by the finite element method, and conducted earnest research on the behavior of the “C” -shaped elastic body in front view as shown in the front view in FIG. 1 at the time of vibration input. As a result, the elastic body is composed of two types of elastic elements having different rubber hardness, which are fixed integrally with each other at least partially, so that the dynamic spring constant of the elastic body has a peak value at the resonance frequency. Can be greatly reduced compared to an elastic body made of one type of elastic element, and the peak frequency of the dynamic spring constant can be shifted to a higher frequency side or a lower frequency side than the resonance frequency. I found.
And it was thought that the occurrence of surging can be effectively prevented by applying this to the vibration isolator.

Based on such knowledge, the vibration isolator of the present invention includes an outer cylinder, an inner cylinder disposed inside the outer cylinder, a covering rubber part surrounding the inner cylinder, and an outer cylinder continuously with the covering rubber part. An anti-vibration device comprising a rubber member made of a rubber leg portion extending to the cylinder side and connecting the outer cylinder and the inner cylinder at two locations in the circumferential direction of the outer cylinder. The member is constituted by integrally fixing at least part of two types of rubber elastic bodies having different rubber hardness, and the two types of rubber elastic bodies having different rubber hardness of the rubber member are respectively The outer cylinder and the inner cylinder are connected to each other .

  Preferably, each rubber leg portion of the rubber member is positioned with a plane including the central axis of the outer cylinder interposed therebetween, and each of the two types of rubber elastic bodies having different rubber hardnesses of the rubber member is disposed on the plane. The rubber elastic bodies are fixed to each other over the axial direction of the outer cylinder at the covering rubber portion.

  Preferably, each of the two types of rubber elastic bodies having different rubber hardness of the rubber member is disposed on each of the one side and the other side in the axial direction of the outer cylinder, and the rubber elastic bodies are mutually connected. In a cross section perpendicular to the central axis of the outer cylinder, the rubber member is fixed to the entire region in the direction.

Preferably, both rubber hardnesses of the two types of rubber elastic bodies are within the range of 40 to 60 in terms of JIS A hardness, and the difference in rubber hardness between the two types of rubber elastic bodies is 5 to 5 in terms of JIS A hardness. Within the range of 15.
Here, “JIS A hardness” refers to durometer hardness obtained by a durometer hardness test using a type A durometer as defined in JIS K6253.

FIG. 2 shows an analysis result using the finite element method as a graph of the change of the dynamic spring constant with respect to the frequency of the input vibration.
In this numerical analysis, as shown in the front view of FIG. 1, an elastic body having a letter “C” in front view, a through-hole provided in a substantially central region, a peripheral surface to which the inner cylinder is fixed, and an outer surface A state in which each of the outer peripheral surfaces of the elastic body to which the inner peripheral surface of the cylinder is fixed is used as a fixed end is modeled, and an arrangement area of two types of elastic elements having different rubber hardnesses with JIS A hardnesses 44 and 55 is illustrated. As shown in FIG. 3, the change in the dynamic spring constant when vibration was input was calculated for each change.

Here, in the elastic body shown in the front view in FIG. 3A, elastic elements having different hardnesses are arranged on one side and the other side of the plane indicated by the phantom line in the figure, and the elastic elements are mutually connected. , Fixed in the contact area on the imaginary line. The elastic bodies shown in side views in FIGS. 3B to 3D have elastic elements having different hardnesses arranged on one side and the other side in the axial direction, and the elastic elements are mutually connected. These are fixed at positions indicated by virtual lines in the figure. Here, in FIGS. 3B to 3D, the volume ratio of the elastic elements of hardness 55 and hardness 45 is made different as shown in the figure.
For the sake of reference, FIG. 2 also shows the analysis results of each elastic body composed of only one elastic element having a rubber hardness of 45 or 55.

  As shown in FIG. 2, in the elastic body in which two kinds of elastic elements having different rubber hardnesses shown in FIGS. 3A to 3D are fixed to each other, the rubber hardness is either 45 or 55. There are two peaks corresponding to the dynamic spring constant peaks of the elastic body composed of only the elastic elements (hereinafter referred to as “elastic body with hardness 45” and “elastic body with hardness 55”, respectively). However, in the elastic body shown in FIGS. 3A to 3D, the two corresponding peaks are greatly reduced as compared with the respective peaks of the elastic body having a hardness of 45 and the elastic body having a hardness of 55. You can see that

  Therefore, according to the vibration isolator of the present invention, the rubber member that connects the outer cylinder and the inner cylinder is made of two types of rubber elastic bodies having different rubber hardness, such as the elastic body illustrated in FIG. The structure is made by fixing them together at least partially so that the required static spring characteristics required for engine mounts or motor mounts can be exhibited, while the dynamic spring constant of the rubber member itself is at its peak. Therefore, the surging phenomenon can be achieved without increasing the manufacturing cost, increasing the mass of the apparatus, and deteriorating the quiet performance due to the arrangement of the “independent mass member” or the like in the prior art. Can be effectively prevented.

Here, from the analysis result shown in FIG. 2, in the elastic body in which the hardness of the elastic element is differentiated between the one side and the other side divided by the plane including the central axis shown in FIG. It can be seen that the two corresponding peaks are reduced to about half with respect to the dynamic spring constant peaks of the elastic body and the elastic body of hardness 55, respectively.
This is due to the fact that the elastic area on one side and the elastic element on the other side, which are divided by the plane including the central axis, are different from each other, so that the mutual fixing area of these elastic elements is small. Then, the two legs extending from the inner cylinder side to the outer cylinder side with respect to the input vibration vibrate independently of each other without greatly affecting each other. It can be considered that the frequency of the two peaks is not shifted greatly to the low frequency side or the high frequency side, and the peak value decreases.

  Therefore, in the above-described vibration isolator, like the elastic body shown in FIG. 3A, each rubber leg portion of the rubber member is positioned with a plane including the central axis of the outer cylinder, and the rubber member Each of the two types of rubber elastic bodies having different rubber hardness is disposed on each of the one side and the other side divided into the plane, and the rubber elastic bodies are connected to each other by the covering rubber portion and the outer cylinder. When fixed over the axial method, both of the two peaks are greatly increased without significantly shifting the frequency of the two dynamic spring constant peaks based on the self-excited vibration of the rubber leg portions of different hardness. Can be reduced.

  Further, from the results shown in FIG. 2, the elastic spring constant shown in FIGS. 3B to 3D is an elastic body in which elastic elements having different hardness are arranged on one side and the other side in the axial direction. In addition to the reduction of the two peaks, at least one of the frequencies at which the two peaks are generated is the frequency at which the corresponding peak is generated for each of the elastic body having a hardness of 45 and the elastic body having a hardness of 55. It turns out that it has shifted to the low frequency side or the high frequency side.

  This means that an elastic element having a rubber hardness of 45 and an elastic element having a rubber hardness of 55, which are integrally fixed to a large area, constitute an elastic body as shown in FIGS. 3 (b) to 3 (d). However, when the vibration is input, the two elastic elements exert a great influence on each other, thereby suppressing the amplification of the vibration of the elastic element itself. This is probably due to this.

  Therefore, in the above-described vibration isolator, each of the two types of rubber elastic bodies having different rubber hardness of the rubber member, such as the elastic bodies shown in FIGS. When the rubber elastic bodies are fixed to each other over the entire area of the rubber member in a cross section orthogonal to the central axis of the outer cylinder, the dynamic spring constant of the rubber member In addition, the peak generation frequency can be shifted to a higher frequency side or a lower frequency side than the frequency of the input vibration in which surging occurs in the conventional apparatus.

  2, among the elastic bodies shown in FIGS. 3B to 3D, the smaller the volume occupied by the elastic element having a rubber hardness of 55, the closer to the peak frequency of the elastic body having a hardness of 55. While the peak of the generated dynamic spring constant decreases, the peak of the dynamic spring constant generated near the peak frequency of the elastic body having a hardness of 45 tends to increase, and two rubber hardnesses differ from each other. It can be seen that the frequency at which two peaks corresponding to the peaks of the elastic body with hardness 45 and the elastic body with hardness 55 shift to the high frequency side or the low frequency side according to the volume ratio of the elastic elements.

  Here, in the above-described vibration isolator, the rubber hardness of each of the two types of rubber elastic bodies is set within a range of 40 to 60 in JIS A hardness, and the difference in rubber hardness between the two types of rubber elastic bodies. When the JIS A hardness is in the range of 5 to 15, the required static spring constant of the rubber member is secured, the dynamic magnification (ratio of the static spring constant to the static spring constant) is reduced, and the durability The effect of reducing the dynamic spring constant peak of the rubber member and the effect of suppressing the input vibration by the rubber member are high based on the rubber member being composed of two types of rubber elastic bodies. It can be made compatible in dimension.

In other words, when the rubber hardness of at least one rubber elastic body is less than 40, the vibration generation side member and the transmission side member cannot be connected sufficiently firmly due to the lack of the static spring constant of the rubber member. On the other hand, when the rubber hardness is more than 60, there is a concern that the vibration isolation performance is lowered and the durability of the rubber member is deteriorated due to an increase in the dynamic magnification of the rubber member.
Further, when the difference in rubber hardness is less than 5, the difference in rubber hardness is small, so that the effect of reducing the peak of the dynamic spring constant of the rubber member based on the difference in rubber hardness is not sufficiently exhibited during vibration input. As a result, a surging phenomenon may occur depending on the input vibration. On the other hand, if the difference in rubber hardness exceeds 15, the rubber hardness of one of the two types of rubber elastic bodies is too small. Or, since it is too large, there is a possibility that the input vibration due to the shear deformation of the rubber member is not properly absorbed.

It is a front view which shows the elastic body model used for the numerical analysis by a finite element method. It is a graph showing the analysis result by a finite element method by the change of the dynamic spring constant with respect to the frequency of input vibration. It is a figure which shows the arrangement | positioning aspect of two types of elastic elements of each elastic body model used for the numerical analysis. 1 is a cross-sectional view of an apparatus showing an embodiment of the present invention. It is a longitudinal cross-sectional view containing the center axis line of the apparatus which shows other embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
The vibration isolator 1 illustrated in FIG. 4 is arranged, for example, in a cylindrical outer cylinder 2 and the inner side of the outer cylinder 2, with the center axis position slightly shifted above that of the outer cylinder 2 in the figure. The inner cylinder 3 has a rectangular rectangular tube shape in the cross-sectional view shown in the figure, and the outer cylinder 2 and the rubber member 4 that connects the inner cylinder 3 to each other.
In addition, although illustration is abbreviate | omitted, an inner cylinder can also be made into the cylindrical shape which makes | forms a circle by a cross sectional view.

Here, the rubber member 4 includes a thin covering rubber portion 4a surrounding the inner tube 3 and covering the inner tube 3, and two pieces extending to the outer tube 2 side continuously to the covering rubber portion 4a. The outer cylinder 2 and the inner cylinder 3 are connected at two locations in the circumferential direction of the outer cylinder 2 by the two rubber leg parts 4b.
In the rubber member 4 configured in this manner, two spaces 5a and 5b are formed between the outer cylinder 2 and the inner cylinder 3 in the axial direction of the inner and outer cylinders in the figure. .

  Such a vibration isolator can attach the outer cylinder 2 to a member on either the vibration generation side or the vibration transmission side, and attach the inner cylinder 3 to the other member for use. In FIG. 4, the input vibration in the vertical direction in FIG. 4 from the vibration generation side is mainly absorbed by the shear deformation of the rubber member 4, thereby functioning to prevent the input vibration from being transmitted to the vibration transmission side member.

  Here, in a spring-mass system in which the rubber leg portions 4b that connect the outer cylinder 2 and the inner cylinder 3 to each other are used as a spring and a mass, and a vibration having a natural vibration frequency, for example, a frequency around 1000 Hz is input. In the embodiment shown in FIG. 4, in order to cope with the surging phenomenon, each of the rubber leg portions 4b may cause a surging phenomenon in which the amplitude and the dynamic spring constant increase due to self-excited vibration. Each rubber leg portion 4b of the member 4 is positioned with a plane P including the central axis of the outer cylinder 2 separated, and half of the covered rubber portion 4a existing on one side of the rubber member 4 divided by the plane P. The rubber part 4b and the half part of the covering rubber part 4a existing on the other side and the rubber leg part 4b are composed of two types of rubber elastic bodies Rh1, Rh2 having different rubber hardness, Mutual beam elastic body Rh1, Rh2, with the coating rubber portion 4a, to fix over the axial direction of the outer cylinder 2.

  4, a stopper rubber member 6 that functions as a stopper when the rubber member 4 is greatly deformed in the vertical direction in the figure is provided on the entire inner peripheral surface of the outer cylinder 2. The stopper rubber member 6 is provided continuously with each of the portions 4b, and the hardness of the stopper rubber member 6 is also different between the one side and the other side of the plane P, but this is not an essential configuration of the present invention.

In the vibration isolator 1 shown in FIG. 4, the rubber elastic body Rh <b> 1 and the rubber elastic body Rh <b> 2 have a sufficiently small mutual sticking area, and therefore, when the vibration is input, the rubber elastic body Rh <b> 1 extends from the inner cylinder 3 side to the outer cylinder 2 side. The two rubber leg portions 4b independently vibrate independently without greatly affecting each other.
As a result, according to the vibration isolator 1, the peak value of the dynamic spring constant of the rubber member 4 is not greatly shifted, for example, the rubber member is made of one type of rubber elastic body. Since it can be reduced to about half of the peak value in the apparatus, it is necessary for the engine mount or motor mount based on the rubber member 4 comprising two types of rubber elastic bodies Rh1 and Rh2 of high hardness and low hardness. The surging phenomenon can be effectively prevented while the required static spring characteristics are exhibited.

  Here, preferably, the rubber hardness of the rubber member Rh1 having a relatively low hardness and the rubber member Rh2 having a high hardness are both in the range of 40-60 in terms of JIS A hardness, The difference in rubber hardness between the rubber elastic bodies Rh1 and Rh2 is set within the range of 5 to 15 with the same hardness.

By the way, although manufacture of said vibration isolator is abbreviate | omitted illustration, for example, first, each of an outer cylinder and an inner cylinder are arrange | positioned in the mold which opened the mold, and then the mold is clamped, Each of two types of viscous fluid raw rubber is injected into the cavity formed inside from two injection ports to fill the cavity, and then the raw rubber is vulcanized.
By manufacturing the device 1 in this manner, the rubber elastic bodies Rh1 and Rh2 having different rubber hardness can be integrally fixed to each other in their contact areas.

FIG. 5 shows another embodiment in a longitudinal sectional view including the direction of the central axis of the apparatus. The apparatus 10 shown in FIG. 5 has two types of rubber elastic bodies constituting the rubber member arranged in a different mode from the apparatus 1 shown in FIG. 4, and the apparatus 10 has a configuration other than the arrangement mode of the rubber elastic bodies. The configuration is the same as that of the apparatus 1.
That is, the rubber member 14 of the apparatus 10 shown in FIG. 5 has two types of rubber elastic bodies Rh1 and Rh2 having different rubber hardness respectively disposed on one side and the other side of the outer cylinder 2 in the axial direction. The rubber elastic bodies Rh <b> 1 and Rh <b> 2 are configured to be fixed over the entire area of the rubber member 14 in a cross section orthogonal to the central axis C of the outer cylinder 2.

In the vibration isolator 10 shown in FIG. 5, the rubber elastic bodies Rh1 and Rh2 that are integrally fixed to each other with a large area exhibit different behaviors in amplitude and phase from each other when vibration is input. Two types of elastic bodies Rh1 and Rh2 having different hardnesses exert a great influence on each other and function to suppress the vibration amplitude of the rubber elastic body itself.
Thereby, according to this vibration isolator 10, the peak of the dynamic spring constant of the rubber member 14 is reduced, and the frequency of the peak is higher than the frequency of the input vibration that causes surging in the conventional device. Alternatively, since the shift is to the low frequency side, it is possible to effectively eliminate the possibility of the surging phenomenon without significantly reducing the required static spring constant.

In FIG. 5, the volume ratio of the two types of rubber elastic bodies Rh1 and Rh2 arranged on one side and the other side in the axial direction of the outer cylinder 2 is 1: 1, but this ratio is limited to this. Therefore, the two types of rubber elastic bodies Rh1 and Rh2 can be arranged in a volume ratio of 1: 4 or 4: 1, for example, although not shown.
According to the analysis results described above, in the vibration isolator 10 as shown in FIG. 5, two dynamic spring constant peaks occur in a predetermined frequency range, and the volume of two types of rubber elastic bodies. By changing the ratio, the frequency of occurrence of at least one peak can be shifted to a lower frequency side or a higher frequency side with the increase or decrease of the two peaks, so the volume ratio of the two types of rubber elastic bodies can be increased. By selecting appropriately, the occurrence of surging can be prevented more reliably.

  In the device 10 shown in FIG. 5, the stopper rubber member 16 covering the inner peripheral surface of the outer cylinder 2 is also made to have a different rubber hardness between the one side part and the other side part in the axial direction of the outer cylinder. ing.

DESCRIPTION OF SYMBOLS 1, 10 Vibration isolator 2 Outer cylinder 3 Inner cylinder 4, 14 Rubber member 4a, 14a Cover rubber part 4b Rubber leg part 5a, 5b Space Rh1 Low hardness rubber elastic body Rh2 High hardness rubber elastic body

Claims (4)

An outer cylinder, an inner cylinder disposed inside the outer cylinder, a covering rubber portion surrounding the inner cylinder, and extending continuously toward the outer cylinder side of the covering rubber portion. An anti-vibration device comprising a rubber member composed of respective rubber legs connected at two locations in the circumferential direction of the outer cylinder,
The rubber member is constituted by integrally fixing at least a part of two types of rubber elastic bodies having different rubber hardness ,
The two types of rubber elastic bodies having different rubber hardnesses of the rubber member are respectively connected to the outer cylinder and the inner cylinder .   While each rubber leg portion of the rubber member is positioned across a plane including the central axis of the outer cylinder, each of the two types of rubber elastic bodies having different rubber hardnesses of the rubber member is divided by the plane. 2. The vibration isolator according to claim 1, wherein the anti-vibration device is disposed on each of the first side and the second side, and the rubber elastic bodies are fixed to each other over the axial direction of the outer cylinder at the covering rubber portion.   Each of the two types of rubber elastic bodies having different rubber hardnesses is arranged on one side and the other side in the axial direction of the outer cylinder, and the rubber elastic bodies are arranged at the center of the outer cylinder. The anti-vibration device according to claim 1, wherein the rubber member is fixed over the entire area in a cross section perpendicular to the axis.   Each of the two types of rubber elastic bodies has a rubber hardness in the range of 40 to 60 in JIS A hardness, and the difference in rubber hardness between the two types of rubber elastic bodies in the range of 5 to 15 in JIS A hardness. The vibration isolator according to any one of claims 1 to 3, wherein the anti-vibration device is provided inside.

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