Vehicle vibration isolation structure

Abstract

To realize a vehicle vibration absorption structure that can reduce costs and spaces while reducing vibration transmitted to a vehicle body by suppressing resonant oscillation on a mount member generated by vibration transmitted from a unit as a source of vibration.SOLUTION: A vehicle rear part structure includes: a unit 10 mounted as a source of vibration in a vehicle; a mount member 30 disposed between the unit 10 and vehicle bodies 20 and 70 to connect therebetween; and a stay 40 connecting the unit 10 and the mount member 30 to be fixed to the unit and the mount member. The stay 40 includes: a first fixation portion 42 fixed to the unit 10; a second fixation portion 44 fixed to the mount member 30; and an expansion portion 46 that is expandable. The natural frequency of the mount member 30 fixed to the stay 40 is adjusted by the setting of elasticity of the expansion portion 46.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle vibration isolation structure. [Background technology]

[0002] To address NVH (noise, vibration, and harshness), which can reduce vehicle comfort, devices and structures are known that control and reduce the noise and vibration transmitted to the vehicle body from various on-board units such as the engine and motor.

[0003] Patent Document 1 discloses a vibration isolation structure for a front-end module that suppresses pulsating noise and vibration transmitted from multiple on-board units, which are vibration sources mounted at the front of a vehicle, through the vehicle body into the vehicle interior. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2014 / 041961 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, when the natural frequencies of the on-board unit (vibration source) and the components of the vibration transmission system are similar, resonance is likely to occur. Because resonance deteriorates NVH characteristics, it is necessary to suppress resonance. One way to do this is to adjust the natural frequency of the on-board unit (vibration source). However, adjusting the natural frequency of the on-board unit itself is often difficult to achieve, as it requires a design review after the unit development is complete. If such measures were to be taken, additional processing and machining steps would be required, as well as capital investment, resulting in additional costs.

[0006] Another approach to suppressing resonance is to adjust the natural frequency of components in the vibration transmission system from the unit to the vehicle body, such as the mount member used to connect the unit to the vehicle body. For example, the natural frequency of the mount member can be adjusted by adding a separate component to the mount member to change its mass or by reinforcing its shape. Another approach is to add a vibration control device to suppress the vibration of the mount member. However, in either case, additional components and devices incur additional costs. Furthermore, such measures may not be possible due to installation space constraints.

[0007] Therefore, this specification discloses a vehicle vibration-damping structure that suppresses resonant vibration in the mounting member caused by vibration transmitted from the unit, which is the vibration source, thereby reducing vibration transmitted to the vehicle body while keeping costs and space down. [Means for solving the problem]

[0008] The vehicle vibration-damping structure disclosed in this specification comprises a unit that is mounted on a vehicle and serves as a vibration source, a mount member that is provided between the unit and the vehicle body and connects the two, and a stay that connects the unit and the mount member and is fixed to both, wherein the stay has a first fixed portion that is fixed to the unit, a second fixed portion that is fixed to the mount member, and an expandable / contractible portion, and the natural frequency of the mount member fixed to the stay is adjusted by setting the expansion / contraction characteristics of the expandable / contractible portion. [Effects of the Invention]

[0009] According to the vehicle vibration-damping structure disclosed in this specification, the natural frequency of the mount member fixed to the stay is adjusted by setting the expansion and contraction characteristics of the expansion and contraction section of the stay. In other words, the natural frequency of the mount member can be adjusted simply by adjusting the expansion and contraction characteristics of the expansion and contraction section of the stay, without the need to add any additional components or devices, thereby eliminating the need for extra cost or space. As a result, a vehicle vibration-damping structure can be realized that suppresses resonant vibration in the mount member caused by vibration transmitted from the unit, which is the vibration source, thereby reducing vibration transmitted to the vehicle body while reducing cost and space. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic front view of a vehicle vibration-proof structure. [Figure 2] FIG. 2 is a perspective view of FIG. 1, showing a schematic perspective view of the shape of a stay. [Figure 3] FIG. 10 is a perspective view showing the periphery of the extension / contraction portion of the stay, with a portion thereof being enlarged. [Figure 4] FIG. 10 is an image diagram of frequencies when the natural frequency of the engine mount is adjusted. DETAILED DESCRIPTION OF THE INVENTION

[0011] The vehicle vibration-damping structure will be described below with reference to the drawings. In each drawing, "Fr," "Up," and "W" indicate the front, top, and width directions of the vehicle, respectively. The left and right directions in the width direction of the vehicle are defined as the left and right directions when looking forward from the vehicle.

[0012] 1 is a schematic front view of a vehicle vibration-damping structure. The vehicle vibration-damping structure includes an engine 10, vehicle bodies 20 and 70, an engine mount 30, a stay 40, a rubber engine mount 50, and a vehicle-body mount 60. Note that the vehicle vibration-damping structure disclosed in this specification will be described using the engine 10 as the unit mounted on the vehicle and serving as a vibration source, but is not limited to this and can also be applied to other units such as a motor. The unit may also include a power transmission mechanism such as a transmission.

[0013] The engine mount 30 is a member used when mounting the engine 10 on the vehicle bodies 20 and 70, connecting the two. Similarly, the vehicle body mount 60 is a member that connects the engine 10 to the vehicle bodies 20 and 70. The engine mount 30 is disposed on the engine 10 side, and the vehicle body mount 60 is disposed on the vehicle body 20 and 70 side. As shown in FIG. 1 , the engine mount 30 fixed to the engine 10 is connected to the vehicle bodies 20 and 70 via the engine mount rubber 50 and the vehicle body mount 60. In other words, the engine mount 30, the engine mount rubber 50, and the vehicle body mount 60 can be said to constitute a vibration transmission system between the engine 10 and the vehicle bodies 20 and 70.

[0014] As shown in FIG. 1 , an engine mount 30 is attached to the upper part of the left end of the engine 10 in the vehicle width direction. As will be described later, the engine 10 and engine mount 30 are fixed not only at one location at the upper left end of the engine 10 but also at another location via a stay 40. Furthermore, an engine mount rubber 50 is attached to the engine mount 30 on the vehicle body 20 and 70 side. As described above, one end of the engine mount rubber 50 is attached to the engine mount 30, and the other end is attached to the vehicle body mount 60. Note that the engine mount rubber 50 uses a vibration-damping material with vibration-absorbing properties, such as rubber, to suppress vibrations transmitted from the engine mount 30 to the vehicle body mount 60. In this example, the vehicle body mount 60 is attached to the vehicle bodies 20 and 70.

[0015] As described above, because the engine 10 and the engine mount 30 are fixed, vibrations originating from the engine 10 are transmitted to the engine mount 30. These vibrations are then transmitted to the vehicle bodies 20 and 70 via the engine mount rubber 50 and the vehicle body mount 60. On the other hand, transmission of vibrations originating from the engine 10 as a vibration source to the vehicle bodies 20 and 70 is reduced by the engine mount rubber 50. However, resonance may occur depending on the natural frequency of the components of the vibration transmission system (hereinafter referred to as the "transmission system" as appropriate) until the vibrations generated by the engine 10 are transmitted to the vehicle bodies 20 and 70, and the vibrations may become stronger.

[0016] Furthermore, in addition to vibrations originating from the engine 10, vibrations originating from multiple other on-board units are also transmitted to the vehicle bodies 20 and 70. In this case, if the natural frequencies of the units are similar and vibrations are transmitted from multiple transmission systems, resonance is likely to occur. In particular, in electric vehicles, the natural frequencies of the units and the vibration system are often similar, resulting in a state where frequencies are concentrated. In this case, resonance with the vibration of one of the units is likely to occur in the transmission system.

[0017] Therefore, in the vehicle vibration-damping structure disclosed in this specification, the natural frequency of the engine mount 30, which is a transmission system, is adjusted to avoid resonance in the transmission system. Specifically, the rigidity of the stay 40 fixed to the engine mount 30 is adjusted to suppress the resonant vibration and reduce the vibration transmitted to the vehicle bodies 20 and 70. This is explained in detail below.

[0018] In this example, as described above, the engine 10 and engine mount 30 are fixed not only at one location on the left end portion of the engine 10, but also at another location via the stay 40. As shown in Fig. 1, the stay 40 is disposed above the engine 10 and engine mount 30 so as to straddle both of them. The stay 40 has bolt holes (not shown) and is fixed to the engine 10 and engine mount 30, respectively, with fixing members 80, 82 such as bolts.

[0019] Next, the stay 40 will be described with reference to FIG. 2. FIG. 2 is a schematic perspective view of FIG. 1, illustrating the shape of the stay 40. The stay 40 is a generally L-shaped, steel plate-like member. The stay 40 includes an engine-side fixed portion 42, a mount-side fixed portion 44, and an expandable portion 46. The engine-side fixed portion 42 is fixed to the engine 10 by a fixing member 80 (see FIG. 1). The mount-side fixed portion 44 is fixed to the engine mount 30 by a fixing member 82 (see FIG. 1). The expandable portion 46 is provided between the engine-side fixed portion 42 and the mount-side fixed portion 44 and is made of an expandable member. That is, the stay 40 is partially made of an expandable member. In this example, a bead, which is a bulge with a U-shaped cross section, is formed on the stay 40 as an expandable member, and a beaded bent shape (hereinafter referred to as a "bead bent shape") is set. That is, the bead bent shape is used to set the expansion and contraction characteristics of the expandable portion 46. The stretching characteristics will be explained below with reference to FIG.

[0020] FIG. 3 is a perspective view showing the vicinity of the telescopic portion 46 of the stay 40, with a partially enlarged view. In this example, the natural frequency of the engine mount 30, which is a transmission system, is adjusted. However, the natural frequency of the engine mount 30 is largely determined by the rigidity of the portion where the engine mount 30 is fixed to the engine 10. That is, the natural frequency of the engine mount 30 is largely determined by the attachment rigidity between the engine 10 and the engine mount 30 and the rigidity of the stay 40. Therefore, in this example, the natural frequency of the engine mount 30, which is a vibration transmission system extending from the engine 10 to the vehicle-side mount 60, is adjusted by adjusting the rigidity of the telescopic portion 46 by setting the telescopic characteristics of the telescopic portion 46. As described below, the natural frequency of the engine mount 30 is adjusted by adjusting the degree of telescopic extension of the telescopic portion 46 of the stay 40. For example, multiple stays 40 with different telescopic portions 46 are prepared, and the natural frequency is adjusted depending on which stay 40 is used, or the degree of bending is adjusted later.

[0021] As described above, the expansion / contraction characteristics of the expansion / contraction portion 46 are set by setting a bead bend shape for the expansion / contraction portion 46. By setting the expansion / contraction portion 46 in a bead bend shape, a spring component is created, making it easier to bend the expansion / contraction portion 46, and the degree of expansion / contraction can be adjusted by changing the bending condition. In other words, by setting a bead bend shape for the expansion / contraction portion 46, the rigidity of the expansion / contraction portion 46 can be adjusted. Since the natural frequency is determined by two factors: the mass and the spring (rigidity), for example, the natural frequency can be increased by increasing the rigidity of the expansion / contraction portion 46. In the vehicle vibration-damping structure disclosed in this specification, this characteristic is utilized to adjust the rigidity of the expansion / contraction portion 46 (rigidity of the stay 40) to pinpoint the natural frequency of the engine mount 30 fixed to the stay 40 to a desired value. This will be explained in more detail using Figure 3.

[0022] FIG. 3 shows an expandable portion 46 having a bead bend shape (hereinafter referred to as the "bead bend portion" where appropriate). The portion BB enclosed by the dashed dotted line in FIG. 3 is an enlarged cross-sectional view of the BB portion. Adjusting the rigidity of the expandable portion 46 means adjusting the degree of expansion and contraction by changing the bending state of the expandable portion 46, or more specifically, adjusting the dimensions of the bead bend portion. For example, decreasing the width W of the bead bend portion reduces the rigidity, while increasing the width W increases the rigidity. Increasing the height H of the bead bend portion reduces the rigidity, while decreasing the height H increases the rigidity.

[0023] The dimensions of the bead bend can be adjusted by adjusting the bending radius in the same way as adjusting the width W and height H. The "bending radius" refers to the radius from the bent position to the center of the bend when bending. Figure 3 shows three bending radii R. For example, increasing the bending radius R reduces the rigidity, and decreasing the bending radius R increases the rigidity.

[0024] As described above, by adjusting the dimensions (shape) of the bead bend portion, that is, by setting the expansion and contraction characteristics of the expansion portion 46, the rigidity of the stay 40 can be adjusted. As a result, the natural frequency of the engine mount 30 can be precisely set to a desired value, and resonance can be suppressed. How to set the engine mount 30 to suppress resonance, that is, how to set the frequency of the engine mount 30, will be described using FIG. 4.

[0025] FIG. 4 is a diagram illustrating the frequency when the natural frequency of the engine mount 30 is adjusted. In FIG. 4, the frequency fa of the engine mount 30 when the stay 40 is not attached to the engine mount 30 is indicated by a two-dot chain line. The frequency fb of the engine mount 30 when the stay 40 is fixed to the engine mount 30 is indicated by a dashed line. The frequency fx indicated by a solid line is the frequency of the engine mount 30 when the shape of the bead bend portion is adjusted, i.e., when the expansion / contraction characteristics of the expansion portion 46 are set. The frequency fx can be set to any value between the frequencies fa and fb by adjusting the shape of the bead bend portion. For example, if resonance occurs due to the natural frequencies of the components in the transmission system being close to each other (frequency bands becoming dense) before the vibration generated by the engine 10 is transmitted to the vehicle bodies 20 and 70, the natural frequency of the engine mount 30, which is one part of the transmission system, can be changed. This enables vibration isolation (dividing the vibration path). Specifically, the natural frequency of the engine mount 30 is increased by reducing the bending radius R of the bead bend portion and increasing its rigidity. As a result, the frequency of the engine mount 30, shown by the solid line in Figure 4, slides to the right. In other words, the frequency of the engine mount 30 is moved out of the crowded frequency band, preventing resonance.

[0026] As described above, in the vehicle vibration-damping structure disclosed in this specification, the natural frequency of engine mount 30 can be pinpointed to a desired value simply by adjusting the shape of the bead bend of expansion / contraction section 46. In other words, even if resonance occurs between engine 10 and each transmission system through the transmission system, increasing the vibration transmitted to vehicle bodies 20 and 70, the natural frequency of engine mount 30 can be adjusted simply by adjusting the expansion / contraction characteristics of expansion / contraction section 46. Therefore, since there is no need to add any additional members or devices, it is possible to suppress resonant vibration and reduce the vibration transmitted to vehicle bodies 20 and 70 while keeping costs and space down.

[0027] It should be noted that the above description is merely an example, and the vehicle vibration-damping structure only requires that the stay 40 has an expandable / contractible section 46, and that the natural frequency of the engine mount 30 fixed to the stay 40 can be adjusted by setting the expansion / contraction characteristics of the expandable section 46. Therefore, other configurations of the vehicle vibration-damping structure may be changed as appropriate. For example, in this example, the stay 40 is made of iron, and the expandable section 46, which is a part of the stay 40, has a bead-bent shape so as to be an expandable section, but the expandable section 46 itself may be made of a different material such as a rubber member, so that the spring component (rigidity) can be changed. [Explanation of symbols]

[0028] 10 engine, 20, 70 body, 30 engine mount, 40 stay, 42 engine side fixing part, 44 mount side fixing part, 46 expansion part, 50 engine mount rubber, 60 body side mount, 80, 82 fixing member.

Claims

1. A unit that is installed in a vehicle and serves as a vibration source, a mount member provided between the unit and the vehicle body to connect them; a stay that connects the unit and the mount member and is fixed to both; Equipped with The stay is a first fixing portion fixed to the unit; a second fixing portion fixed to the mount member; A stretchable stretchable part; and the stretchable portion is a bead portion having a U-shaped cross section formed at a location where the first fixing portion and the second fixing portion are connected, The natural frequency of the mount member fixed to the stay is adjusted by setting the expansion and contraction characteristics of the expansion and contraction section. A vehicle vibration-proof structure characterized by:

2. 2. The vehicle vibration isolation structure according to claim 1, The first fixing portion, the second fixing portion, and the stretchable portion are a single plate-like member connected to each other. A vehicle vibration-proof structure characterized by:

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