Soundproof member, and soundproof structure and vehicle provided with same

Abstract

[Problem] To provide a means capable of reducing noise caused by vibration of a soundproof member in a structure in which the soundproof member is mounted to a gearbox. [Solution] A soundproof member is used for vibration‑isolated mounting on the outside of a gearbox that includes a plurality of gears and one or more gear‑meshing portions so as to be spaced apart from the gearbox and so as to cover at least one of the gear‑meshing portions in a plan view. The soundproof member includes a plate‑shaped vibration‑suppressing member and a vibration-reduction member. The plate-shaped vibration-suppressing member has: one end that is positioned on a side on which vibration is incident; the other end that is positioned in a direction in which the vibration propagates; and a wedge-shaped portion that is positioned in at least a part from said one end to the other end, and that has a thickness that changes while satisfying the following formula (1). The plate-shaped vibration-suppressing member thereby suppresses the vibration. The vibration-reduction member is provided on the wedge-shaped portion so as to include a part corresponding to the other end of the vibration‑suppressing member.　Formula (1): h(x) = ε･xn+h1 In formula (1), x represents a distance measured from an arbitrary position on the other end side as a starting point toward said one end, h(x) represents the thickness of the plate-shaped vibration-suppressing member at a distance x from the arbitrary position, h1 represents the thickness of the plate-shaped vibration-suppressing member at the arbitrary position, ε represents a positive constant, and n represents a real number of 2 or higher.

Description

Soundproofing material, and soundproofing structure and vehicle using the same.

[0001] This invention relates to a soundproofing member, and to a soundproofing structure and vehicle using the same.

[0002] There are many sound sources inside a car. Because quietness from both inside and outside the vehicle is required, various soundproofing measures are taken in automobiles. In particular, soundproofing measures are necessary in areas close to the source of loud noises, such as the engine, transmission, and drivetrain.

[0003] According to Non-Patent Document 1 (Ji Chengyao et al., Vibration-Acoustic Analysis of Automotive Transmission Covers, Abstracts of the 35th Anniversary Technical Exchange Meeting of the Vibration Control Engineering Research Association, SDT22004, Control Engineering Research Association, 2022), some automobile transmissions generate unique noises, which are reduced by attaching soundproofing covers. However, although the soundproofing cover is fixed to the transmission body, it is possible that vibration transmission may also cause radiated sound from the soundproofing cover.

[0004] Furthermore, in Non-Patent Document 1, a simple soundproof cover is attached to a jig simulating a transmission, and the vibration acceleration and sound pressure level when the jig is vibrated are measured. The jig and soundproof cover are also modeled using the finite element method (FEM), and vibration acoustic analysis is performed. The document then reports on changes to the mounting method of the soundproof cover, changes to the laminated structure, the addition of ultrafine fiber material, and the effects of drilling holes.

[0005] The soundproofing measures disclosed in Non-Patent Document 1 mentioned above are still insufficient, and further improvements are needed. In particular, there remains a strong demand to reduce noise from gearboxes, which are a major source of noise.

[0006] Therefore, the present invention aims to provide a means that can reduce noise from the gearbox.

[0007] A soundproofing member according to one embodiment of the present invention is for vibration isolation support on the outside of a gearbox having a plurality of gears and at least one gear meshing portion, so as to be separated from the gearbox and so as to cover at least one of the gear meshing portions when viewed from above, and includes a plate-shaped vibration damping member and a damping member. The plate-shaped vibration damping member has one end located on the side from which the vibration is incident, another end located in the direction in which the vibration propagates, and a wedge-shaped portion located in at least a part from one end to the other. The thickness of the wedge-shaped portion changes in accordance with the following formula (1). The damping member is provided on the wedge-shaped portion so as to include the portion corresponding to the other end of the plate-shaped vibration damping member. The plate-shaped vibration damping member thereby suppresses vibration: h(x) = ε・x ｎ +h １ ...Equation (1) In Equation (1), x represents the distance measured from an arbitrary position on the other end toward the one end, h(x) represents the thickness of the plate-shaped vibration damping member at a distance x from the arbitrary position, h １ ε represents the thickness of the plate-shaped vibration damping member at the arbitrary position, ε represents a positive constant, and n represents a real number of 2 or more.

[0008] Figure 10A shows a schematic plan view illustrating the configuration of a soundproofing member according to the first embodiment of the present invention. Figure 2 is a cross-sectional view taken along the line II-II shown in Figure 1. Figure 3 is an explanatory diagram illustrating the cross-sectional shape of the plate-shaped vibration damping member that constitutes the soundproofing member shown in Figure 1. Figure 4 is a schematic plan view illustrating the configuration of a soundproofing member according to the second embodiment of the present invention. Figure 5 is a cross-sectional view taken along the line V-V shown in Figure 4. Figure 6 is a perspective view illustrating the internal configuration of a gearbox that functions as a reduction gear for an electric vehicle. Figure 7 shows how the soundproofing member according to the first embodiment is vibration-damped and supported on the outside of the gearbox. Figure 8 is a side view taken from direction A shown in Figure 7, showing how the soundproofing member is vibration-damped and supported (fixed) to the gearbox. Figure 9 shows the relationship between the position of the soundproofing member and the position of the gears and gear meshing parts installed inside the gearbox when the soundproofing member is vibration-damped and supported on the outside of the gearbox (shown transparently). Figure 10A shows the shape and size of the plate-shaped vibration damping member that constitutes the soundproofing member manufactured in Example 1. Figure 10B shows the shape and size of the soundproofing member fabricated in Example 1. Figure 10C shows an overview of the gearbox mechanism used in Example 1 to evaluate the soundproofing performance of the soundproofing member, in which a speed increaser is placed between the motor and the reducer. Figure 10D is a Campbell diagram showing the sound pressure level when the sound generated when the gearbox mechanism shown in Figure 10C is driven is measured with a microphone. Figure 10E is a graph showing the results of evaluating the soundproofing performance of the soundproofing member in Example 1. Figure 11A is a structural model of the two gear meshing parts in the reducer (gearbox) when the soundproofing performance of the soundproofing member was evaluated by CAE analysis in Example 2. Figure 11B is a graph showing the results of evaluating the soundproofing performance of the soundproofing member by CAE analysis in Example 2. Figure 11B(a) is a graph of ERP when an excitation force is generated by setting a relative displacement between the nodes of the gear meshing part 10a (input meshing part). Furthermore, Figure 11B(b) is a graph of ERP when an excitation force is generated by setting a relative displacement between the nodes of the gear meshing portion 10b (output meshing portion). Figure 12 is a graph showing the results of evaluating the sound insulation performance of the sound insulation member using acceleration [dB] as an indicator in Example 3.

[0009] One embodiment of the present invention is a soundproofing member including a plate-shaped vibration damping member and a damping member for vibration isolation support on the outside of a gearbox having a plurality of gears and at least one gear meshing portion, so as to be separated from the gearbox and so as to cover at least one of the gear meshing portions when viewed from above, wherein the plate-shaped vibration damping member has one end located on the side from which the vibration is incident, another end located in the direction in which the vibration propagates, and a wedge-shaped portion located at least a part from the one end to the other end, the thickness of which changes as satisfying the following formula (1), the plate-shaped vibration damping member thereby suppresses the vibration, and the damping member is provided on the wedge-shaped portion so as to include the portion of the plate-shaped vibration damping member corresponding to the other end, the soundproofing member being: h(x) = ε・x ｎ +h １ ...Equation (1) In Equation (1), x represents the distance measured from an arbitrary position on the other end toward the one end, h(x) represents the thickness of the plate-shaped vibration damping member at a distance x from the arbitrary position, h １ ε represents the thickness of the plate-shaped vibration damping member at the arbitrary position, ε represents a positive constant, and n represents a real number of 2 or more. According to the soundproofing member of this embodiment, in a structure in which the soundproofing member is attached to the gearbox, noise from the gearbox can be reduced.

[0010] Furthermore, according to another embodiment of the present invention, a soundproofing structure is provided comprising a gearbox and the soundproofing member attached to the outside of the gearbox. Furthermore, according to yet another embodiment of the present invention, a vehicle having the above-described soundproofing structure is provided.

[0011] Embodiments of the present invention will be described below with reference to the drawings, but the technical scope of the present invention is not limited to the following forms. Note that the dimensional ratios in the drawings are exaggerated for illustrative purposes and may differ from the actual ratios. In this specification, "a to b" indicating a range means "a or more and b or less". Unless otherwise specified, operations and measurements of physical properties, etc., are performed under room temperature (20 to 25°C) / relative humidity 40 to 50%.

[0012] [Configuration of Soundproofing Member] <First Embodiment> Figure 1 is a schematic plan view showing the configuration of the soundproofing member 100 according to the first embodiment of the present invention. Figure 2 is a cross-sectional view taken along the line II-II shown in Figure 1. Figure 3 is an explanatory diagram for illustrating the cross-sectional shape of the plate-shaped vibration damping member 110 that constitutes the soundproofing member 100 shown in Figure 1.

[0013] As shown in Figures 1 and 2, the soundproofing member 100 includes a plate-shaped vibration damping member 110 and a damping member 120. A mortar-shaped recess is provided in a part of the plate-shaped vibration damping member 110, and this recess constitutes a symmetrical wedge-shaped portion 110W as shown in Figure 2. The damping member 120 is joined to the center of the recess. The soundproofing member 100 having this configuration is vibration-damped and supported on the outside of a gearbox (not shown) and is used to reduce vibrations generated from the gearbox.

[0014] (Plate-shaped vibration damping member) The plate-shaped vibration damping member 110 may be made of a material that can reduce noise generated from the gearbox, but it is preferable that it be made of a metal material such as iron or steel, as this allows the soundproofing effect of the soundproofing member to be more pronounced due to the small vibration damping effect (damping coefficient) and is easy to handle. The plate-shaped vibration damping member 110 is a plate-shaped member having a predetermined width, length and thickness.

[0015] Referring to Figure 3, the cross-sectional shape of the plate-shaped vibration damping member 110 (the shape of the right half of the symmetrical structure) will be described. The cross-section of the plate-shaped vibration damping member 110 has a length l and a thickness h. The length l is usually less than or equal to the size of the gearbox, for example, 30 mm to 1000 mm. The cross-section of the plate-shaped vibration damping member 110 has one end e1 and the other end e2 in the direction of length l.

[0016] On one end e1 side of the plate-shaped vibration damping member 110, a thick portion 110C is provided, and on the other end e2 side, a wedge-shaped portion 110W is provided. The thick portion 110C has a constant thickness hc. The size of the constant thickness hc corresponds to the thickness of the plate-shaped vibration damping member 110 and is, for example, 2 to 100 mm. In order to suppress the thickness of the plate-shaped vibration damping member 110, the size of the constant thickness hc is preferably 30 mm or less, and more preferably 20 mm or less. When the soundproof member 100 is used, vibration is incident from one end e1 side of the plate-shaped vibration damping member 110 and propagates toward the other end e2 side.

[0017] As described above, in the illustrated embodiment, a wedge-shaped portion 110W is provided on the other end e2 side of the plate-shaped vibration damping member 110. The wedge-shaped portion 110W is provided adjacent to the thick portion 110C, for example, and is provided from a position eW between one end e1 and the other end e2 to the other end e2. In this wedge-shaped portion 110W, the thickness h gradually decreases from the position eW toward the other end e2. That is, the size of the thickness h of the wedge-shaped portion 110W is the largest at the position eW and the smallest at the other end e2. The thickness h of this wedge-shaped portion 12W satisfies the following formula (1): h(x) = ε · x ｎ + h １ ... Formula (1) In Formula (1), x represents the distance measured toward one end e1 starting from an arbitrary position on the other end e2 side, h(x) represents the thickness of the plate-shaped vibration damping member 110 at the distance x from the arbitrary position, h １ represents the thickness of the plate-shaped vibration damping member 110 at the arbitrary position, ε represents a positive constant, and n represents a real number of 2 or more.

[0018] The arbitrary position on the other end e2 side that is the measurement starting point of the distance x in the above formula (1) is an arbitrary position closer to the other end e2 than one end e1, for example, the other end e2. The distance x is measured along the radius of the circle when the depression in the shape of a mortar bowl is circular, for example. Also, h １ corresponds to the thickness of the plate-shaped vibration damping member 110 at the measurement starting point of the distance x (for example, the other end e2). The value of h １ may be 0 or more, but is preferably greater than 0. However, h１ If the h is too large, the acoustic black hole effect caused by providing the wedge-shaped portion 110W on the plate-shaped vibration damping member 110 will decrease, １ It is preferably 1 mm or less, and more preferably 0.5 mm or less.

[0019] By providing such a wedge-shaped portion 110W on the other end e2 side of the plate-shaped vibration damping member 110, a so-called acoustic black hole structure is realized. This suppresses the reflection of vibration waves at the other end e2 of the plate-shaped vibration damping member 110, and effectively attenuates vibrations incident from one end e1 to the other end e2. As a result, the noise generated by the soundproofing member 100 itself due to vibrations propagated from the gearbox to the soundproofing member 100 is also reduced, and the overall noise can be effectively reduced. Preferably, at least a part of the wedge-shaped portion 110W is located closer to the other end e2 than to the one end e1, in other words, closer to the other end e2 than the midpoint between the one end e1 and the other end e2. The other end e2 of the wedge-shaped portion 110W does not necessarily have to be located at the end of the plate-shaped vibration damping member 110. For example, if the thickness is constant (= h １ The thinnest portion of the plate-shaped vibration damping member 110 may be positioned on the end side of the plate-shaped vibration damping member 110, rather than on the other end e2 of the wedge-shaped portion 110W. In this case, it is not sufficient for the damping member 120 to be provided only on the thinnest portion of the plate-shaped vibration damping member 110, but it must be provided so as to include the portion of the plate-shaped vibration damping member 110 that corresponds to the other end e2 of the wedge-shaped portion 110W.

[0020] Regarding the frequency at which vibration damping is possible by the wedge-shaped portion 110W, by increasing the length L of the wedge-shaped portion 110W, lower frequency vibrations can be effectively damped. The length L of the wedge-shaped portion 110W is measured along the radius of the circle, for example, when the mortar-shaped depression is circular. The length L of the wedge-shaped portion 110W is preferably 70% or more of the length l of the plate-shaped vibration damping member 110, and more preferably 75% or more. By increasing the proportion of the wedge-shaped portion 110W in the plate-shaped vibration damping member 110, vibrations can be damped more effectively. Although not shown in the figures, the left half of a symmetrical plate-shaped vibration damping member 110 also has a similar configuration.

[0021] (Damping Member) The damping member 120, which is provided so as to include the portion corresponding to the other end e2 of the plate-shaped vibration damping member 110, plays the role of converting the vibration energy collected at the other end e2 by the acoustic black hole structure into thermal energy and damping it. The damping member 120 is made of, for example, a plate-shaped viscoelastic material. The thickness of this plate-shaped damping member 120 is preferably greater than the thickness of the plate-shaped vibration damping member 110 at the position corresponding to the other end e2 of the plate-shaped vibration damping member 110. The viscoelastic material constituting the damping member 120 is preferably a polymer material such as rubber. The specific gravity of the damping member 120 is preferably about the same as or greater than the specific gravity of the plate-shaped vibration damping member 110. With such a damping member 120, the vibration energy collected at the other end e2 can be efficiently damped. As a result, the noise generated by the soundproofing member 100 itself due to vibrations transmitted from the gearbox to the soundproofing member 100 is also reduced, and the overall noise can be effectively reduced.

[0022] In the illustrated embodiment, the damping member 120 is provided on the plate-shaped vibration damping member 110 in a portion facing the wedge-shaped portion 110W, including a portion corresponding to the other end e2 of the plate-shaped vibration damping member 110 (a portion that overlaps with the other end e2 when the soundproofing member is viewed in plan) (Figure 2). In this case, an intermediate layer, such as an adhesive layer of a certain thickness, may be interposed between the plate-shaped vibration damping member 110 and the damping member 120. The damping member 120 may also be provided directly on the wedge-shaped portion 110W of the plate-shaped vibration damping member 110, or via the intermediate layer as needed. In any of these arrangements, the damping member 120 can perform its function and sufficiently dampen the vibration energy transmitted while damping the wedge-shaped portion 110W of the plate-shaped vibration damping member 110. In Figure 2, the damping member 120 is provided on the side of the plate-shaped vibration damping member 110 where the recess is formed (the upper surface of the plate-shaped vibration damping member 110 in Figure 2). However, in some cases, it may be provided on the side of the plate-shaped vibration damping member 110 where the recess is not formed (the lower surface of the plate-shaped vibration damping member 110 in Figure 2), as long as it is in a position facing the wedge-shaped portion 110W.

[0023] <Second Embodiment> Next, the configuration of the soundproofing member 100' according to the second embodiment of the present invention will be described with reference to Figures 4 and 5. Figure 4 is a schematic plan view showing the configuration of the soundproofing member 100' according to the second embodiment of the present invention. Figure 5 is a cross-sectional view along the line V-V shown in Figure 4. Parts common to the first embodiment will not be described, and only parts that are unique to the second embodiment will be described. Note that the same reference numerals will be used to describe the same components as in the first embodiment described above, and redundant descriptions will be omitted.

[0024] In the second embodiment, the arrangement of the thickened portion 110C, the wedge-shaped portion 110W, and the damping member 120 in the plate-shaped vibration damping member 110 is different from that of the first embodiment.

[0025] Specifically, in this embodiment, a wedge-shaped portion 110W, whose thickness changes in accordance with formula (1) of the plate-shaped vibration damping member 110, is provided in a direction perpendicular to a pair of parallel sides of the plate-shaped vibration damping member 110. As a result, in a cross-section perpendicular to the pair of parallel sides, two wedge-shaped portions 110W with different orientations are provided symmetrically.

[0026] Even with the soundproofing member 100' having the configuration described above, a so-called acoustic black hole structure is realized in the wedge-shaped portion 110W. As a result, the reflection of vibration waves at the other end e2 of the plate-shaped vibration damping member 110 is suppressed, and vibrations incident from one end e1 to the other end e2 can be effectively attenuated. As a result, the noise generated by the soundproofing member 100' itself due to vibrations propagated from the gearbox to the soundproofing member 100' is also reduced, and the overall noise can be effectively reduced. In this embodiment, the position of one end e1 is any position located between the starting positions eW of the two wedge-shaped portions 110W corresponding to each other end e2.

[0027] [Gearbox Configuration] A gearbox is a transmission device that has multiple gears. As a result of having multiple gears, a gearbox has at least one gear meshing section. When the gearbox is in operation, meshing errors at the gear meshing section act as an excitation force, generating vibration (noise). For example, the motor that drives an electric vehicle is positioned at the front of the vehicle, with the motor's rotation axis oriented perpendicular to the vehicle's longitudinal direction, and the rotation of this motor is transmitted to a reduction gear.

[0028] Figure 6 is a perspective view illustrating the internal configuration of the gearbox 200, which functions as a reduction gear for an electric vehicle. In Figure 6, the white arrow indicates the front of the vehicle. Note that Figure 6 is merely a diagram illustrating the functions of the gear mechanism 10 and the parking mechanism 21, and therefore the arrangement of the gear mechanism 10 and the parking mechanism 21 shown in Figure 6 does not necessarily correspond to the arrangement of the gear mechanism 10 and the parking mechanism 21 in this embodiment, which will be described below.

[0029] As shown in FIG. 6, the speed reducer 3 is mainly composed of a gear mechanism 10 that decelerates the rotational input from the motor, a parking mechanism 21 that stops the rotation of the gear mechanism by being coupled to a part of the gear mechanism, and a gear case 4 that houses these components inside. The gear case 4 shown in FIG. 6 houses a part of the parking mechanism 21 and the gear mechanism 10 that is coupled to the parking mechanism 21 above in the vertical direction, and stores oil for circulating the gear mechanism at the bottom. However, the specific configuration of the gear case 4 is not limited to this.

[0030] The gear mechanism 10 is composed of three gear sets: an input gear 11, a second gear 12, and a final gear 13. The input gear 11 and the second gear 12 mesh with each other with external teeth (gear meshing part 10a), and the second gear 12 and the final gear 13 mesh with each other with external teeth (gear meshing part 10b). Since it is necessary to lubricate the meshing parts of these three gears 11-13 with oil, the entire gear mechanism 10 is housed inside the gear case 4. In this specification, the description of the lubrication device for lubricating the meshing parts with oil is omitted.

[0031] The input gear 11 is directly connected to the output shaft of the motor. The gear ratios between the input gear 11 and the second gear 12, and between the second gear 12 and the final gear 13 are determined so that the rotational speed of the motor is decelerated. The gear mechanism 10, which is a combination of these three gears 11-13, decelerates the rotation (rotational input) of the motor to a predetermined rotational speed while aligning the rotational direction of the motor and the rotational direction of the final gear 13. The rotation from the motor transmitted to the final gear 13 is transmitted to a pair of drive shafts extending left and right of the vehicle via a differential gear (not shown). The rotation transmitted to the drive shaft is transmitted to the drive wheels at the tip of the drive shaft.

[0032] The parking mechanism 21 stops the rotation of the gear mechanism 10 by coupling with a part of it, and releases the rotation stop by releasing the coupling. The stopping of the rotation of the gear mechanism 10 is called locking, and the release of the rotation stop is called unlocking. The parking mechanism 21 consists of a rotatable manual shaft 23 and manual plate 24, a detent spring 25 that biases them toward their initial positions, a sliding parking rod 26, a swingable parking pawl 27, and a parking gear 28. The entirety of these components 23 to 27 is actually housed inside a cover, but this cover is not shown in Figure 6.

[0033] [Applications of the soundproofing member] Figure 7 shows the soundproofing member 100 according to the first embodiment being vibration-damped and supported on the outside of the gearbox 200. Figure 8 is a side view taken from direction A shown in Figure 7, showing how the soundproofing member 100 is vibration-damped and supported (fixed) to the gearbox 200. Figure 9 shows the relationship between the position of the soundproofing member 100 and the positions of the gears 11 to 13 and gear meshing parts 10a and 10b installed inside the gearbox 200 when the soundproofing member 100 is vibration-damped and supported on the outside of the gearbox 200 (shown through the glass).

[0034] As shown in FIGS. 7 and 8, the soundproof member 100 according to this embodiment is installed in the gearbox 200 and used for soundproofing purposes to reduce noise from the gearbox. Thereby, the soundproof member 100 is integrated with the gearbox 200 to constitute a soundproof structure 300. As described above, the gearbox 200 has a plurality of gears 11 to 13 and two gear meshing portions 10a and 10b. However, the soundproof member 100 (the plate-shaped vibration damping member 110 and the damping member 120) is vibration-proof supported outside the gearbox 200 so as to be separated from the gearbox 200 as shown in FIG. 8. In the present embodiment, it is vibration-proof supported (fixed) using a fixing member 310 in holes formed outside the gearbox 200 (the four ○ marks in the soundproof member shown in FIG. 7). According to such a configuration, the soundproof member 100 can be easily removed, and there is an advantage that the assemblability and disassemblability of the soundproof structure 300 are improved. At this time, the fixing member 310 is composed of a bolt 312 and a rubber washer 314. Further, when the gearbox 200 is connected to a motor mount (not shown), the soundproof member 100 is interposed between the gearbox 200 and the motor mount. At this time, the fixing member 310 also serves as a fixing member for fixing the gearbox 200 and the motor mount. In addition, when a connecting member for connecting them is arranged between the gearbox 200 and the motor mount, the soundproof member 100 is interposed between the gearbox 200 and the connecting member. At this time, the fixing member 310 also serves as a fixing member for fixing the gearbox 200 and the connecting member. By adopting these configurations, it is possible to effectively suppress the propagation of noise derived from the gearbox 200 and the noise generated by the soundproof member 100 itself to the motor mount.

[0035] Furthermore, as shown in Figure 9, the soundproofing member 100 is vibration-damping supported (installed) on the outside of the gearbox 200 so as to cover one of the gear meshing portions 10a, 10b of the gearbox 200 (in this embodiment, the gear meshing portion 10a with a higher meshing order) when the soundproofing member 100 is viewed from above (when viewed from a direction perpendicular to the plate-shaped vibration damping member 110), and so as to cover the gear bearing of the input gear 11. Here, regarding the "meshing order" of the gear meshing portion, the phenomenon that occurs once per rotation of the gear is called the rotational first-order component, and n times that is called the rotational n-th-order component. In a gearbox such as a reduction gear connected to a motor, the meshing order of the phenomenon that occurs n times per rotation of the motor is n, based on the rotation of the motor. Furthermore, a "gear bearing" is a bearing that connects the rotating shaft of the gear to the gearbox, and vibrations generated at the gear meshing point are transmitted to the gearbox via this gear bearing.

[0036] As described above, the soundproofing member according to this embodiment is vibration-damping supported on the outside of the gearbox so as to cover at least one of the gear meshing parts when viewed from above. In this case, the part that covers the gear meshing part in plan view may be a plate-shaped vibration damping member 110 or a damping member 120. Here, when the gearbox has multiple gear meshing parts, it is preferable that the soundproofing member is vibration-damping supported on the gearbox so as to cover the gear meshing part that does not have the smallest meshing order when viewed from above, and it is more preferable that it is vibration-damping supported on the gearbox so as to cover the gear meshing part with the largest meshing order, as shown in Figure 9. By covering the meshing part with a large meshing order (i.e., a high frequency of meshing order sound) in this way, the acoustic black hole effect, which is advantageous for reducing high-frequency vibrations, can be utilized more effectively. Furthermore, for the same reasons as described above, it is preferable that the soundproofing member is vibration-damping supported by the gearbox so as to further cover at least one of the gear bearings of the two gears that constitute a gear meshing portion where the meshing order is not the minimum (preferably the maximum), as shown in Figure 9.

[0037] Generally, when a rotating body such as a transmission or speed reducer acts as an excitation source, the frequency of the excited vibrations differs depending on the number of teeth on the gears. The cut-on frequency of the soundproofing member 100 according to this embodiment (the minimum frequency of vibrations that exhibit a damping effect due to the acoustic black hole effect) is preferably smaller than the frequency of vibrations generated at the maximum rotation of gears 11 and 12 in the gear meshing portion (gear meshing portion 10a in Figure 9) covered by the soundproofing member 100. This effectively reduces vibrations generated in the gear meshing portion and provides sufficient soundproofing performance. It is known that the cut-on frequency of the soundproofing member 100 according to this embodiment, which utilizes the acoustic black hole effect, is proportional to the thickness hc of the thickened portion 110C and inversely proportional to the square of the length L of the wedge-shaped portion 110W, provided the material is the same. It is also known that, if the dimensions are the same, it is affected by the physical properties (Young's modulus, density, Poisson's ratio) of the constituent material of the soundproofing member 100. Therefore, by adjusting the dimensions and physical properties of the soundproofing member 100, it is possible to control the cut-on frequency of the soundproofing member 100 to a desired value.

[0038] Furthermore, according to another embodiment of the present invention, a vehicle having the soundproofing structure described above is also provided. Gearboxes such as reduction gears are commonly used in motor-equipped automobiles such as electric vehicles and hybrid electric vehicles. Therefore, the soundproofing structure according to this embodiment, which has excellent soundproofing performance, is highly effective when applied to automobiles and other vehicles where there is a very strong demand for reducing noise generated inside the vehicle.

[0039] The soundproofing member and soundproofing structure according to the present invention have been described above using embodiments. However, the present invention can be appropriately added, modified, and omitted by those skilled in the art within the scope of its technical concept. For example, the configuration, shape, and size of each part of the soundproofing member described in the above embodiments and examples are examples only, and other configurations, shapes, and sizes may be used. For example, in the soundproofing member 100 according to the first embodiment, only one mortar-shaped recess (wedge-shaped part that shows the acoustic black hole effect) is provided, but multiple such mortar-shaped recesses may be provided in a single soundproofing member.

[0040] The following embodiments are also included in the scope of the present invention: a soundproofing member according to claim 1 having the features of claim 2; a soundproofing member according to claim 2 having the features of claim 3; a soundproofing member according to claim 2 or 3 having the features of claim 4; a soundproofing member according to any one of claims 1 to 4 having the features of claim 5; a soundproofing member according to any one of claims 1 to 5 having the features of claim 6; a soundproofing member according to claim 6 having the features of claim 7; a soundproofing structure comprising a gearbox and a soundproofing member according to any one of claims 1 to 7; and a vehicle having the soundproofing structure according to claim 8.

[0041] The present invention will be described in more detail below with reference to examples. However, the technical scope of the present invention is not limited to the following examples.

[0042] [Example 1] (Fabrication of soundproofing member) A flat plate (2 mm thick) made of SPCC (cold-rolled steel sheet) was prepared as the raw material for the plate-shaped vibration damping member that constitutes the soundproofing member. Next, this flat plate was cut to the size shown in Figure 10A (unit: mm). Next, a wedge-shaped portion was formed in the center of this flat plate, and a circular butyl rubber sheet (2 mm thick; manufactured by Inoac Corporation, Calmflex® RZ-2) was attached to the center of the wedge-shaped portion as a damping member to produce the soundproofing member shown in Figure 10B having a circular wedge-shaped portion. Here, the thickness hc of the thickened portion of the wedge-shaped portion, which is arranged symmetrically on both sides in the vertical cross-section of the wedge-shaped portion, is 2.0 mm, the length L of the wedge-shaped portion is 45 mm, and the minimum thickness h １ The thickness of the wedge-shaped portion was 0.2 mm, and the wedge-shaped portion was manufactured such that the thickness h of the wedge-shaped portion changes while satisfying the following formula (2) (in formula (1), h １ =0.2, ε=1.8 / 45 ２ (n=2). The diameter of the circular damping member was set to 45 mm.

[0043] h(x)=(1.8 / 45 ２ ) x ２+0.2 ...Equation (2) (Evaluation of sound insulation characteristics of sound insulation material) Here, as shown in Figure 10C, the sound insulation characteristics of the sound insulation material were evaluated using a gear change mechanism in which a speed increaser was placed between the motor and the reduction gear. The speed increaser has two gear meshing parts, and the input meshing gear ratio at the motor-side gear meshing part (gear meshing part (A) in Figure 10C) was 1:4.53. The output meshing gear ratio at the reduction gear-side gear meshing part (gear meshing part (B) in Figure 10C) was 1:1.02. As a result, the speed increaser increases the motor rotation speed by 4.62 times overall. In this experiment, the sound insulation material was fixed to the gearbox of the reduction gear using a fixing member as shown in Figure 8 (the tightening torque of the bolts that are the fixing members was set to 3 Nm).

[0044] Figure 10D is a Campbell diagram showing the sound pressure level when the sound generated when the transmission mechanism shown in Figure 10C is driven is measured with a microphone. A Campbell diagram is a graph in which the sound pressure level is represented by the size and color of the circles, with frequency on the vertical axis, rotational speed on the horizontal axis, and rotational order on the diagonal axis. By obtaining this, the order of the sound pressure level, rotational speed, and frequency can be determined. Note that the horizontal axis in Figure 10D represents the motor rotational speed [RPM], and the vertical axis represents the frequency [Hz].

[0045] In this experiment, the radiated sound when the motor was swept up and swept down from 0 to 2200 rpm was measured using a microphone placed 100 mm away from a soundproofing member attached to the gearbox. As a result, the first-order component of the output meshing part of the speed increaser (gear meshing part (B) in Figure 10C) showed the highest sound pressure level and highest frequency. Therefore, in evaluating the soundproofing performance, the overall sound pressure level (dBA) of this component was calculated. Similar evaluations were also performed for cases where no soundproofing member was placed on the gearbox (Comparative Example 1) and for cases where a plate-shaped vibration damping member without a wedge-shaped part and damping member was placed as is (Comparative Example 2). The results are shown in Figure 10E.

[0046] As shown in Figure 10E, it can be seen that the sound pressure level in Example 1 is significantly reduced compared to Comparative Examples 1 and 2.

[0047] [Example 2] (Evaluation of sound insulation characteristics by CAE analysis) 3D models of the sound insulation member shown in Figures 1 and 2 and the electric vehicle reduction gear shown in Figure 9 were fabricated, and the sound insulation characteristics were evaluated by CAE (Computer-Aided Engineering) analysis. Specifically, finite element (FE) analysis was performed using the analysis software MSC Nastran (manufactured by Hexagon). In this case, the boundary conditions of the sample were fully constrained in the part where the reduction gear case is bolted to the motor case, and the sample was meshed with tetrahedral elements. As a model of the rubber washer, which is a fixing member for vibration-damping support of the sound insulation member on the outside of the reduction gear, a spring constant of 1 × 10 was set for these fixing parts. －３ Spring elements with a value of [N / mm] were placed. Furthermore, bolts were not modeled as fixing members. In addition, when creating the 3D models of the soundproofing members and the speed reducer, the physical property parameters of these constituent materials were adopted from the values ​​shown in Tables 1 and 2 below.

[0048]

[0049]

[0050] Furthermore, when evaluating the sound insulation performance, the structure of the two gear meshing sections 10a and 10b in the reduction gear (gearbox) was modeled as shown in Figure 11A. Then, in each of the gear meshing sections 10a or 10b, a relative displacement (transmission error) of 1.0 μm was set between the nodes to create a model of the excitation force.

[0051] In this experiment, the sound insulation performance was evaluated using Equivalent Radiated Power (ERP), which is a simplified method for determining the acoustic contribution from the results obtained from frequency response analysis. The ERP radiated from the surface of the gearbox with or without sound insulation components (Example 2) was calculated. This ERP can be calculated from the element area ΔS of the structural surface and the normal velocity Vn of that surface, and is expressed by the following equations (3) and (4). Note that ERP is the energy emitted per unit time and indicates the acoustic radiation capability from the sound source. Furthermore, eigenvalue calculations for the entire model were performed up to 15,000 Hz, and based on the results, the response when a relative displacement was set at the meshing part was calculated as ERP.

[0052]

[0053] In the formula, ERP ＲＬＣ This represents the radiation loss coefficient, ERP ＲＨＯ This represents fluid density, ERP Ｃ α represents the speed of sound in a fluid. The coefficient α varies depending on the analysis method, but since 1 / 2 is recommended for frequency response analysis, this value was adopted. Then, assuming air at 15°C, ERP ＲＬＣ Let be 1, ERP ＲＨＯ is 1.225 × 10 －９ [kg / mm ３ ] and ERPc is 3.40 × 10 －５ The value was set to [mm / s].

[0054] Figure 11B shows the results of the CAE analysis using the 3D model performed in this manner. Figure 11B(a) is a graph of ERP when an excitation force is generated by setting relative displacements between the nodes of the gear meshing section 10a (input meshing section). Figure 11B(b) is a graph of ERP when an excitation force is generated by setting relative displacements between the nodes of the gear meshing section 10b (output meshing section). Since a speed reducer is a device that reduces rotational speed, the output rotational speed is smaller than the input rotational speed. For this reason, the meshing order is larger in the input meshing section compared to the output meshing section.

[0055] As shown in Figure 11B(b), when a sound-insulating member is vibration-damped and supported on the reduction gear (gearbox) so as to cover the gear meshing portion 10a (input meshing portion) with a higher meshing order, and an excitation force is generated by setting a relative displacement between the nodes of the gear meshing portion 10b (output meshing portion), a reduction in ERP due to the installation of the sound-insulating member was confirmed in the frequency band of 5000 to 9000 Hz compared to the case without the sound-insulating member (Comparative Example 2). Furthermore, as shown in Figure 11B(a), when a sound-insulating member is vibration-damped and supported on the reduction gear (gearbox) so as to cover the gear meshing portion 10a (input meshing portion) with a higher meshing order, and an excitation force is generated by setting a relative displacement between the nodes of the gear meshing portion 10a (input meshing portion), a better reduction in ERP was confirmed in the wider frequency band of 4000 to 10000 Hz compared to Figure 11B(b). This indicates that a superior soundproofing effect can be obtained by vibration-damping and supporting the gearbox with sound-insulating members so as to cover the gear meshing sections with higher meshing orders.

[0056] [Example 3] Using the same experimental setup as in Example 1 described above, the acceleration [dB] derived from the first-order component of the output meshing portion (gear meshing portion (B) in Figure 10C) of the speed increaser was measured. In this case, in Example 3, the acceleration [dB] was measured using an acceleration sensor installed on the thick portion of the plate-shaped vibration damping member constituting the soundproofing member. In Comparative Example 3, the acceleration [dB] was measured using an acceleration sensor installed on the surface of the reduction gear (gearbox) directly below the location where the acceleration sensor was installed in Example 3. The results are shown in Figure 12. Here, the frequency on the horizontal axis of Figure 12 can be determined from the first-order component of the speed increaser output gear meshing shown in Figure 10D.

[0057] As shown in Figure 12, in Example 3, the acceleration was reduced over a wide frequency range of 4000 to 8000 Hz compared to Comparative Example 3. From this, it can be said that the soundproofing member according to the present invention can exhibit excellent soundproofing performance by being vibration-damped and supported on the outside of the gearbox so as to be separated from the gearbox and so as to cover at least one of the gear meshing parts when viewed from above.

[0058] 3 Reducer (gearbox), 4 Gear case, 10 Gear mechanism, 10a, 10b Gear meshing parts, 11 Input gear, 12 Second gear, 13 Final gear, 21 Parking mechanism, 23 Manual shaft, 24 Manual plate, 25 Detent spring, 26 Parking rod, 27 Parking pawl, 28 Parking gear, 100, 100' Soundproofing member, 110 Plate-shaped vibration damping member, 110C Thickened part, 110W Wedge-shaped part, 120 Damping member, 200 Gearbox, 300 Soundproofing structure, 310 Fixing member, 312 Bolt, 314 Rubber washer, e1 One end, e2 Other end, eW Position between one end and the other end, x Distance, h, hc Thickness, l, L Length.

Claims

1. A soundproofing member including a plate-shaped vibration damping member and a damping member for vibration isolation support on the outside of a gearbox having a plurality of gears and at least one gear meshing portion, such that it is spaced apart from the gearbox and covers at least one of the gear meshing portions when viewed from above, wherein the plate-shaped vibration damping member has one end located on the side into which the vibration is incident, another end located in the direction in which the vibration propagates, and a wedge-shaped portion located at least a part from the one end to the other end, the thickness of which changes as satisfying the following formula (1), the plate-shaped vibration damping member thereby suppresses the vibration, and the damping member is provided on the wedge-shaped portion such that it includes the portion of the plate-shaped vibration damping member corresponding to the other end, soundproofing member: h(x) = ε・x ｎ +h １ ...Equation (1) In Equation (1), x represents the distance measured from an arbitrary position on the other end toward the one end, h(x) represents the thickness of the plate-shaped vibration damping member at a distance x from the arbitrary position, h １ ε represents the thickness of the plate-shaped vibration damping member at the arbitrary position, ε represents a positive constant, and n represents a real number of 2 or more.

2. The soundproofing member according to claim 1, wherein the gearbox has a plurality of gear meshing portions, and when viewed from above, the soundproofing member is vibration-dampingly supported by the gearbox so as to cover the gear meshing portion that does not have the minimum meshing order.

3. The soundproofing member according to claim 2, which is vibration-dampingly supported in the gearbox so as to cover the gear meshing portion having the maximum meshing order when viewed from above.

4. The sound-insulating member according to claim 2 or 3, which is vibration-dampingly supported in the gearbox so as to further cover at least one of the gear bearings of the two gears constituting the gear meshing portion having the maximum meshing order when viewed from above.

5. The soundproofing member according to claim 1 or 2, wherein the cut-on frequency is smaller than the frequency of vibration generated at the maximum rotational speed of the gear in the gear meshing portion covered by the soundproofing member.

6. The soundproofing member according to claim 1 or 2, which is vibration-dampingly supported by the gearbox by being fixed to a hole formed on the outside of the gearbox using a fixing member.

7. The soundproofing member according to claim 6, wherein the fixing member comprises a fixing member for fixing the gearbox and the motor mount, or a fixing member for fixing the gearbox to a connecting member for connecting the gearbox to the motor mount, and is vibration-damping supported by the gearbox so as to be interposed between the gearbox and the motor mount or the connecting member.

8. A soundproofing structure comprising: the gearbox; and a soundproofing member according to claim 1 or 2, attached to the outside of the gearbox.

9. A vehicle having the soundproofing structure described in claim 8.

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