Anti-vibration structure and Anti-vibration device

Abstract

To provide a vibration control structure and a vibration control device capable of inexpensively improving sound vibration performance and riding comfort performance even with a simple structure.SOLUTION: This vibration control device 1 has a vibration control structure having an elastic body 4 for elastically connecting an outer peripheral surface of an inner cylinder part 2 and an inner peripheral surface of an outer cylinder part 3. The elastic body 4 contains natural rubber and butadiene rubber as a main rubber component at a mass ratio of natural rubber / butadiene rubber = 50 / 50 to 95 / 5, and contains 15 to 50 parts by mass of a butadiene-styrene random copolymer having an average molecular weight (Mn) of 3000 to 12000 as a softener when the total rubber component is 100 parts by mass.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vibration isolation structure for an anti-vibration device that is applied to a motor mount that supports a drive electric motor (hereinafter referred to as motor) of an electric vehicle (hereinafter referred to as vehicle). [Background technology]

[0002] Unlike vibration isolation devices for internal combustion engines, vibration isolation devices for automobile motors are required to have vibration isolation capabilities against torque fluctuations up to about 10,000 Hz, and in consideration of sound and vibration performance at high frequencies, it is common to use elastic materials with low damping properties to minimize changes in radial rigidity of the vibration isolation device.

[0003] However, lowering the damping of the elastic body reduces its ability to suppress motor vibration, raising concerns about its impact on ride comfort, and there are issues with achieving both of these performance characteristics. Furthermore, in the high-frequency range above 100 Hz, resonance occurs due to the shape of the elastic body, generating vibrations in specific frequency bands that have a negative impact on noise and vibration performance and ride comfort.

[0004] Therefore, a method has been adopted in which the inner and outer cylindrical parts of the vibration-damping device are connected by two types of elastic bodies with different hardness, or elastic protrusions are provided on the elastic body connecting the inner and outer cylindrical parts, thereby causing resonance phenomena in multiple frequency bands and canceling out vibrations (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5693386 [Patent Document 2] Patent No. 7364658 [Patent Document 3] JP 2023-145863 A (paragraphs 0031-0062, tables 1 and 2, and figure 2) Summary of the Invention [Problem to be solved by the invention]

[0006] However, the above-mentioned conventional vibration isolators have problems such as increased production costs due to the use of rubber materials with different hardness and special structures and shapes.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a vibration-damping structure and a vibration-damping device that can improve noise and vibration performance and ride comfort performance at low cost even with a simple structure. [Means for solving the problem]

[0008] Therefore, one aspect of the present invention has an elastic body that elastically connects the outer peripheral surface of the inner cylindrical portion and the inner peripheral surface of the outer cylindrical portion, which contains natural rubber and butadiene rubber as main rubber components in a mass ratio of natural rubber / butadiene rubber = 50 / 50 to 95 / 5, and contains 15 to 50 parts by mass of a butadiene-styrene random copolymer with an average molecular weight (Mn) of 3,000 to 12,000 as a softener for 100 parts by mass of the total rubber component. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a vibration-damping structure and a vibration-damping device that can improve noise and vibration performance and ride comfort performance at low cost even with a simple structure. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a front view showing a vibration-proof structure according to a first embodiment of the present invention. [Figure 2] 1 shows the relationship between input vibration frequency and dynamic spring constant for the first embodiment and a conventional elastic body. [Figure 3] FIG. 4 is a front view showing a vibration-proof structure according to a second embodiment of the present invention. [Figure 4] The relationship between amplitude and dynamic magnification (Kd100 / Ks) of the second embodiment and the conventional elastic body. [Figure 5] FIG. 10 is a front view showing a vibration-proof structure according to a third embodiment of the present invention. [Figure 6] 10 shows the relationship between the input vibration frequency and the dynamic spring constant of the elastic body according to the third embodiment and the conventional elastic body. [Figure 7] FIG. 1(a) is a front view showing a vibration-proof structure according to a fourth embodiment of the present invention; FIG. 1(b) is a front view showing a vibration-proof structure according to a fifth embodiment of the present invention; and FIG. 1(c) is a front view showing a vibration-proof structure according to a sixth embodiment of the present invention. [Figure 8] 1 shows the relationship between the loss factor tanδ (10 Hz) and the dynamic magnification (Kd100 / Ks) of rubber compositions of examples and comparative examples that are applied to the elastic body of the vibration-proof structure of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] [Embodiment 1] The vibration-damping device 1 to which the elastic body 4 of embodiment 1, which is one aspect of the present invention shown in Figure 1, is applied elastically connects the motor of an automobile to a member frame, and elastically supports the motor on the member frame.

[0013] The vibration-damping device 1 has an elastic body 4 that elastically connects the outer peripheral surface of the inner cylindrical portion 2 and the inner peripheral surface of the outer cylindrical portion 3. The inner cylindrical portion 2 is connected to the motor main body side (or member frame side), while the outer cylindrical portion 3 is connected to the member frame side (or motor side). The inner cylindrical portion 2 and the outer cylindrical portion 3 are made of a highly rigid material such as metal, and are generally cylindrical in shape. The inner cylindrical portion 2 is inserted into the outer cylindrical portion 3 approximately coaxially with the outer cylindrical portion 3, and the outer peripheral surface of the inner cylindrical portion 2 and the inner peripheral surface of the outer cylindrical portion 3 are elastically connected by the elastic body 4.

[0014] The elastic body 4 is made of a rubber composition disclosed in Patent Document 3, which contains natural rubber and butadiene rubber as the main rubber components in a mass ratio of natural rubber / butadiene rubber = 50 / 50 to 95 / 5, and is fixed to the outer peripheral surface of the inner cylindrical portion 2 and the inner peripheral surface of the outer cylindrical portion 3 by vulcanization adhesion.

[0015] The natural rubber and butadiene rubber are not particularly limited, and ordinary natural rubber and butadiene rubber used in vibration-proof rubbers can be used (see the same patent document). In particular, when the total amount of natural rubber and butadiene rubber is 95% by mass or more of the total rubber components, a rubber composition with high rubber strength, excellent vibration durability, and low dynamic magnification can be obtained.

[0016] The rubber composition may contain rubber components other than the natural rubber and butadiene rubber, such as isoprene rubber, styrene-butadiene rubber, and ethylene-propylene rubber, within the range that does not impair the above-mentioned effects.

[0017] (Butadiene-styrene random copolymer) The rubber composition contains 15 to 50 parts by mass of a butadiene-styrene random copolymer having an average molecular weight (Mn) of 3,000 to 12,000 as a softener when the total rubber component of the elastomer 4 is 100 parts by mass. The inclusion of this copolymer provides both appropriate flexibility, excellent vibration damping, and low dynamic magnification. In particular, when the average molecular weight of the butadiene-styrene random copolymer is 8,000 to 12,000 and the glass transition temperature (Tg) is between -10°C and 0°C, the effect of achieving both low dynamic magnification and high vibration damping is further enhanced (see the same patent document). Note that the butadiene-styrene random copolymer acts as a softener and does not form an elastomer even when used in combination with a sulfur-based vulcanizing agent for ordinary rubber. Therefore, it is not included in the rubber component or resin component in the present invention.

[0018] (carbon black) When the rubber composition contains 15 to 70 parts by mass of carbon black, it becomes easier to obtain an appropriate static spring constant for the vibration-proof rubber to fulfill its supporting function (same patent document). There are no particular limitations on the carbon black, and various well-known furnace blacks for rubber and furnace blacks for coloring can be used. However, it is preferable to use carbon black having a nitrogen adsorption specific surface area of ​​15 to 80 m. 2 / g of carbon black is preferably used.

[0019] (process oil) The rubber composition may contain process oil in addition to the above components (see the same patent document). The amount of process oil added should be set to an amount sufficient to adjust the rubber hardness (for example, a small amount of 5 parts by mass or less).

[0020] (Vulcanizing agent (crosslinking agent)) In addition to the above components, the rubber composition contains a vulcanizing agent (crosslinking agent) (see the same patent document). Known sulfur-based vulcanizing agents can be used as the vulcanizing agent (crosslinking agent). Vulcanization using sulfur or sulfur-based compounds is preferred because it provides excellent durability to the vibration-proof rubber. In the rubber composition, a butadiene-styrene random copolymer with an average molecular weight (Mn) of 3,000 to 12,000 is hardly crosslinked by sulfur or sulfur-based compounds, and can therefore function as a softener.

[0021] (filler) The rubber composition may contain fillers other than carbon black (see the same patent document). Examples of the fillers include inorganic fillers such as silica, clay, and calcium carbonate, and organic fillers such as polymer fillers. These may be used alone or in combination of two or more.

[0022] (Vulcanization accelerator) When a sulfur compound is used as a vulcanizing agent added to the rubber composition, a well-known vulcanization accelerator can be used in combination (see the same patent document). Specific examples of vulcanization accelerators include sulfenamide compounds, thiazole compounds, guanidine compounds, and thiuram compounds. These vulcanization accelerators may be used alone or in combination of two or more types, and different types may be used in combination.

[0023] (vulcanization aid) When using a sulfur compound as a vulcanizing agent, it is advisable to use a vulcanization aid such as zinc oxide (ZnO) such as zinc white or activated zinc white, or complex zinc white, in combination with a vulcanization aid such as stearic acid or zinc stearate (see the same patent document).

[0024] (anti-aging agent) Since the rubber composition uses natural rubber and butadiene rubber, if the ozone resistance or heat resistance is poor, it is recommended to add a well-known antioxidant (see the same patent document). Examples of antioxidants include carbamate-based antioxidants, phenylenediamine-based antioxidants, phenol-based antioxidants, diphenylamine-based antioxidants, quinoline-based antioxidants, imidazole-based antioxidants, and waxes. These can be used alone or in combination of two or more.

[0025] (processing aids) The rubber composition may contain a processing aid to improve processability (see the same patent document). Compounds typically used in rubber processing may be used as processing aids. Specific examples include higher fatty acids such as ricinoleic acid, stearic acid, palmitic acid, and lauric acid; salts of higher fatty acids such as barium stearate, zinc stearate, and calcium stearate; esters of higher fatty acids such as ricinoleic acid, stearic acid, palmitic acid, and lauric acid; and tackifiers such as terpene resins and coumarone resins for the purpose of imparting tack. These may be used alone or in combination of two or more.

[0026] (coupling agent) In order to adjust vibration characteristics, the rubber composition may contain additives such as a coupling agent between a rubber component and carbon black, a silane coupling agent between a rubber component and silica, or known rubber additives such as a reversion inhibitor, in combination of two or more of them (see the same patent document).

[0027] (Manufacturing of Elastic Body 4) Natural rubber, butadiene rubber, and butadiene-styrene random copolymer are placed in a well-known kneading device, and the above-mentioned additives are further blended together with a vulcanizing agent. The mixture is then kneaded appropriately to obtain an elastic body 4 made from the rubber composition.

[0028] (Manufacture of vibration isolation device 1) First, the outer peripheral surface of the inner cylindrical portion 2 and the inner peripheral surface of the outer cylindrical portion 3 are roughened. Next, a vulcanization adhesive is applied to the bonding area of ​​the elastic body 4 on the outer and inner peripheral surfaces and allowed to dry. Next, the inner cylindrical portion 2 and the outer cylindrical portion 3 are placed in predetermined locations within a cavity heated to a temperature suitable for vulcanizing the elastic body 4. Next, the rubber composition is injected into the cavity and heated for a certain period of time. This causes the vulcanization (crosslinking) reaction of the rubber composition and the reaction of the vulcanization adhesive on the outer and inner peripheral surfaces to proceed simultaneously. As a result, the elastic body 4 is fixed to the outer and inner peripheral surfaces, and the inner cylindrical portion 2 and the outer cylindrical portion 3 are elastically connected by the elastic body 4. When the inner cylindrical portion 2 and the outer cylindrical portion 3, with the elastic body 4 interposed therebetween, are removed from the cavity, the vibration-damping device 1 of this embodiment is obtained.

[0029] Figure 8, which is an excerpt from Figure 2 in the patent document, shows the relationship between the loss factor tanδ (10 Hz) and the dynamic magnification ratio (Kd100 / Ks) at a frequency of 100 Hz for the rubber compositions of Examples 1-9 of the present invention applied to elastic body 4 and the conventional rubber compositions of Comparative Examples 1-6 that do not contain the butadiene-styrene random copolymer. Table 1 below shows the dynamic spring constants Kd100 (N / mm) at a frequency of 100 Hz for the rubber compositions of Examples 1 and 9 and Comparative Examples 4 and 5 in Tables 1 and 2 disclosed in the patent document.

[0030] [Table 1]

[0031] As is clear from the vibration characteristic test results in Figure 8, Examples 1 to 9 provide rubber compositions for elastic body 4 that are superior in low dynamic magnification and high damping properties compared to Comparative Examples 1 to 9. In particular, as shown in the results in Table 1, the rubber composition of Example 1 has a 28% reduction in dynamic spring constant Kd100 (N / mm) compared to the rubber composition of Comparative Example 4. Furthermore, the rubber composition of Example 9 has a 38% reduction in dynamic spring constant Kd100 (N / mm) compared to the rubber composition of Comparative Example 5.

[0032] As described above, with the elastic body 4 of this embodiment, the dynamic magnification is reduced by about 28 to 38% compared to the conventional elastic body for the same damping properties (FIG. 8 and Table 1). Therefore, even if the elastic body 4 does not have a special structure or shape, by using the rubber composition with low dynamic magnification and high damping of this embodiment, it is possible to obtain the effects of low dynamic magnification and high damping properties superior to those of the conventional elastic body, as shown in FIG. 2. Therefore, with the vibration-damping device 1 including the elastic body 4, both low dynamic magnification and high damping properties of the motor mount can be achieved at low cost even with a simple structure, and both ride comfort and noise and vibration performance of the automobile can be achieved at a high level.

[0033] In particular, by changing the average molecular weight and mass portion of the butadiene-styrene random copolymer applied to the elastic body 4 (see the same patent document), it is possible to arbitrarily adjust the characteristics of the vibration-damping device 1 while maintaining the sound vibration performance (rigidity of the motor mount) of the elastic body 4. For example, it is possible to improve ride comfort by increasing the damping performance of the motor mount, or to reduce the rigidity of the motor mount while maintaining the damping performance.

[0034] [Embodiment 2] 3, a vibration-damping device 1 according to a second embodiment of the present invention has a plurality of recessed holes 41 formed in the elastic body 4 of the first embodiment, which penetrate along the axial direction of the inner cylindrical portion 2 and the outer cylindrical portion 3. The openings of the recessed holes 41 at both ends of the elastic body 4 are formed in a substantially V-shape, line-symmetrically with respect to the radial direction of the inner cylindrical portion 2 and the outer cylindrical portion 3.

[0035] Figure 4 shows the relationship between amplitude and dynamic magnification (Kd100 / Ks) for elastic body 4 of the present invention and the conventional elastic body. Table 2 below shows the dynamic magnifications for elastic body 4 of the present invention and the conventional elastic body at an amplitude of 0.01 mm, surrounded by a dotted line where the difference in dynamic magnification becomes large in the amplitude dependency of dynamic magnification in Figure 4. Condition 1 means that the elastic body was prepared so that the loss factor (loss coefficient) at a vibration frequency of 10 Hz, which is an index of damping characteristics, is 0.1. Condition 2 means that the elastic body was prepared so that the loss factor at a vibration frequency of 10 Hz is 0.2.

[0036] [Table 2]

[0037] Regarding the amplitude dependency shown in FIG. 4, when comparing the dynamic magnification of elastic body 4 of the present invention with that of the conventional elastic body at an amplitude of 0.01 mm, where the difference in dynamic magnification becomes large, as shown in Table 2, the dynamic magnification of elastic body 4 of the present invention is reduced by 17 to 20% compared to the conventional elastic body.

[0038] According to the elastic body 4 of the second embodiment, even if the cross-sectional areas of the adjacent elastic blocks 42 separated by the recessed holes 41 are the same, it is possible to obtain effects of low dynamic magnification and high damping properties superior to those of the conventional elastic body, as shown in Fig. 4 and Table 2. Furthermore, by including the butadiene-styrene random copolymer, the motor mount is able to achieve both low dynamic magnification and high damping properties, as in the first embodiment, thereby achieving both a high level of ride comfort and sound and vibration performance.

[0039] [Embodiment 3] 5, the openings of the recessed holes 41a and 41b are formed asymmetrically with respect to the radial direction of the inner and outer cylindrical portions 2 and 3. As a result, the cross-sectional areas S1 and S2 of the elastic blocks 42a and 42b of the elastic body 4 separated by the recessed holes 41a and 41b are different. That is, the cross-sectional area S1 of the elastic block 42a is set larger than the cross-sectional area S2 of the elastic block 42b.

[0040] Figure 6 shows the relationship between input vibration frequency and dynamic spring constant for elastic body 4 of this embodiment and a conventional elastic body. The conventional elastic body is identical to elastic body 4 of this embodiment, except that it is made of the rubber composition of Comparative Examples 1-6, which does not contain the butadiene-styrene random copolymer. Frequency f1 indicates the vibration frequency of elastic block 42a with cross-sectional area S1. Frequency f2 indicates the vibration frequency of elastic block 42b with cross-sectional area S2.

[0041] According to the elastic body of this embodiment, resonance occurs due to the different frequencies of the elastic blocks 42 a and 42 b, reducing the vibrations that occur. In particular, the inclusion of the butadiene-styrene random copolymer further reduces the vibrations caused by the resonance, thereby further improving sound and vibration performance while maintaining damping properties.

[0042] Further, other variations of the third embodiment include the elastic bodies 4 of the fourth, fifth and sixth embodiments shown in FIG.

[0043] In the elastic body 4 of the fourth embodiment shown in Fig. 11(a), the openings thereof extend radially of the inner and outer cylindrical portions 2 and 3, and recessed holes 41c and 41d are formed asymmetrically with respect to the radial direction and are disposed through the inner cylindrical portion 2. Therefore, the elastic blocks 42c and 42d of the elastic body 4 separated by the recessed holes 41c and 41d have different cross-sectional areas S3 and S4.

[0044] In the elastic body 4 of the fifth embodiment shown in Fig. 11(b), one of the recessed holes 41e has a different opening area from the other recessed holes 41f, 41g among a plurality of recessed holes 41e, 41f, 41g formed asymmetrically in the radial direction of the inner cylindrical portion 2 and the outer cylindrical portion 3. Therefore, the cross-sectional areas S5, S6, S7 of the elastic blocks 42e, 42f, 42g of the elastic body 4 separated by the recessed holes 41e, 41f, 41g are different.

[0045] In the elastic body 4 of the sixth embodiment shown in Fig. 11(c), the opening areas of all of the plurality of recessed holes 41h, 41i, 41j, and 41k formed asymmetrically in the radial direction of the inner cylindrical portion 2 and the outer cylindrical portion 3 are different. Therefore, the cross-sectional areas S8, S9, S10, and S11 of the elastic blocks 42h, 42i, 42j, and 42k of the elastic body 4 separated by the recessed holes 41h, 41i, 41j, and 41k are different.

[0046] It is clear that the elastic body 4 of the fourth, fifth and sixth embodiments described above provides the same effects as the elastic body 4 of the third embodiment. [Explanation of symbols]

[0047] 1...Vibration isolation device 2...Inner cylinder 3...Outer cylinder 4...Elastic body 41, 41a, 41b, 41c, 41d, 41e, 41f, 41g, 41h, 41i, 41j, 41k...Currant Hole 42, 42a, 42b, 41c, 41d, 41e, 41f, 41g, 42h, 42i, 42j, 42k...Elastic blocks S1,S2,S3,S4,S5,S6,S7,S8,S9,S10,S11…Cross-sectional area

Claims

1. an elastic body that elastically connects the outer peripheral surface of the inner cylindrical portion and the inner peripheral surface of the outer cylindrical portion; The elastic body contains natural rubber and butadiene rubber as its main rubber components in a mass ratio of natural rubber / butadiene rubber = 50 / 50 to 95 / 5, and when the total rubber component is 100 parts by mass, it contains 15 to 50 parts by mass of a butadiene-styrene random copolymer having an average molecular weight (Mn) of 3,000 to 12,000 as a softener.

2. 2. The vibration-proof structure according to claim 1, wherein the elastic body has a plurality of recesses formed along the axial direction of the inner and outer cylindrical portions.

3. 3. The vibration-proof structure according to claim 2, wherein the elastic blocks of the elastic body separated by the recess have different cross-sectional areas.

4. A vibration isolation device comprising the vibration isolation structure according to claim 1.

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