JP2014121931A - Supporting structure for power plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a supporting structure for a power plant capable of ensuring excellent comfortability with a simple structure.SOLUTION: Both sides in vehicle width direction of a power plant 1 are elastically supported at vehicle body side respectively by a first antivibration device 4 and a second antivibration device 5. Spring constants of the first antivibration device 4 and the second antivibration device 5 in vertical direction are set at a different value each other, thus oscillation in vertical direction and swing in pitch direction in the power plant 1 may be easily linked. Since, the spring constants of the first antivibration device 4 and the second antivibration device 5 in vehicle width direction are set at the constants in which oscillation in vertical direction caused by antiresonance of the power plant 1 is reduced, swing in pitch direction may be easily made in the power plant 1 and oscillation energy in vertical direction of the power plant 1 is distributed. As a result, the vertical vibration of the power plant 1 is attenuated by a simple structure which does not adopt liquid sealing vibration insulation mounting.

Description

  The present invention relates to a power plant support structure, and more particularly to a power plant support structure that can ensure a good ride comfort with a simple structure.

  In automobiles such as passenger cars, a drive unit (power plant) including an engine, a transmission, and the like is supported on the vehicle body by a mount (vibration isolation device). For example, in Patent Document 1, a drive unit (power plant) is arranged in a vehicle body so that a main engine shaft such as a crankshaft is positioned in the vehicle width direction, and both sides of the vehicle width direction are mounted (anti-vibration). A support structure that elastically supports the vehicle body with a device and restricts swinging in the roll direction with a torque rod is disclosed.

  Here, the vertical vibration of the vehicle body caused by the vertical vibration of the power plant when the vehicle is traveling is large in a low frequency range (for example, about 10 to 20 Hz), but the vertical vibration is a spring constant in the vertical direction of the vibration isolator. And the natural frequency band due to the mass of the power plant. However, a large peak of vertical vibration occurs in the frequency range higher than the natural frequency due to antiresonance. In the technique disclosed in Patent Document 1, by using one of the left and right mounts as a liquid-sealed anti-vibration mount, vertical vibration due to anti-resonance is attenuated by liquid column resonance caused by the flow of the sealed liquid in the liquid chamber. The

Japanese Patent No. 3718749

  However, in the technique disclosed in Patent Document 1, one of the left and right mounts is composed of a liquid-sealed anti-vibration mount as compared with a support structure composed of an anti-vibration rubber made of a rubber-like elastic body. As a result, the cost increases.

  Moreover, the liquid seal type vibration-proof mount may cause a phenomenon that the dynamic spring constant increases in a high frequency range (for example, 300 to 500 Hz). As a result, high-frequency vibrations are transmitted to the vehicle body side via the liquid-sealed anti-vibration mount, so that the NV performance (vibration noise performance) deteriorates and the comfort (riding comfort performance) decreases.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a power plant support structure that can secure a good ride comfort with a simple structure.

Means for Solving the Problems and Effects of the Invention

  According to the power plant support structure of the first aspect, the power plant in which the main engine shaft is arranged in the vehicle width direction of the vehicle is supported on the vehicle body side via the vibration isolator. The second vibration isolator elastically supports both sides of the power plant in the vehicle width direction on the vehicle body side. In the first vibration isolator and the second vibration isolator, the vertical spring constants are set to different values, so that it is easy to couple the vertical vibration of the power plant and the swing of the power plant in the pitch direction. it can.

  Furthermore, a spring constant in the vehicle width direction is set in the first vibration isolator and the second vibration isolator so as to reduce vertical vibration due to anti-resonance of the power plant. As a result, oscillation in the pitch direction can easily occur in the power plant, and vibration energy in the vertical direction of the power plant due to anti-resonance can be dispersed. As a result, there is an effect that the vertical vibration of the power plant can be attenuated by a simple structure that does not employ the liquid seal type vibration-proof mount. In addition, if the liquid-sealed anti-vibration mount is not used, the increase of the dynamic spring constant in the high frequency range due to the liquid-sealed anti-vibration mount can be prevented, so that the deterioration of the vibration noise performance can be prevented and the ride comfort can be prevented. There is an effect that performance can be secured.

  According to the power plant support structure according to claim 2, the first vibration isolator and the second vibration isolator are set in the vertical direction of the power plant by setting the natural frequency in the vehicle width direction of the power plant. The peak of the resonance peak appearing on the frequency axis is reduced by anti-resonance of vibration. The natural frequency in the vehicle width direction of the power plant is determined by the vehicle width direction component of the spring constant of the first vibration isolator and the second vibration isolator and the mass of the power plant. There is an effect that the design of the first vibration isolation device and the second vibration isolation device can be facilitated.

  According to the power plant support structure of claim 3, the vibration in the vertical direction of the power plant is attenuated by the vibration damping characteristics of the first vibration isolator and the second vibration isolator. In addition to the effect, the vibration energy in the vertical direction is attenuated, and the ride performance can be further improved.

  According to the support structure for a power plant according to claim 4, the first vibration isolator and the second vibration isolator have a total value of spring constants in the vertical direction and a total value of spring constants in the vehicle width direction. It is set to be smaller. Thereby, the displacement of the power plant in the vertical direction can be easily regulated by the vehicle width direction component of the springs of the first vibration isolation device and the second vibration isolation device. As a result, vibration energy in the vertical direction of the power plant due to anti-resonance can be reduced. Therefore, in addition to the effect of any one of claims 1 to 3, there is an effect that the riding comfort can be improved with certainty.

(A) is the schematic diagram which looked at the support structure of the power plant in one embodiment of this invention from the vehicle front side, (b) is the schematic diagram of the support structure of the power plant in planar view. It is a mimetic diagram showing typically a vibration experiment of vehicles. It is a schematic diagram which shows the relationship between a frequency and floor vertical vibration. It is a two-degree-of-freedom system model of a power plant support structure. It is a simulation result of the vibration level in the vertical direction of the floor. It is a simulation result of the vibration level in the vertical direction of the floor. It is an experimental result of the vibration level in the vertical direction of the floor. It is an experimental result of the vibration level in the vertical direction of the floor.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1A is a schematic view of a power plant 1 support structure according to an embodiment of the present invention as viewed from the front side of the vehicle, and FIG. 1B is a schematic view of the power plant 1 support structure in plan view. It is. In FIG. 1A and FIG. 1B, illustration of an intake / exhaust system, an auxiliary machine, and a vehicle body are omitted for simplification. In addition, arrows X, Y, and Z in FIGS. 1A and 1B indicate the vehicle length direction (front-rear direction), the vehicle width direction (left-right direction), and the up-down direction, respectively.

  As shown in FIG. 1A and FIG. 1B, the power plant 1 is an apparatus in which an engine 2 and a transmission 3 are coupled in series and integrated, and the longitudinal direction (the main engine shaft of the engine 2 (for example, It is mounted horizontally in an engine room (not shown) such that the direction in which the crankshaft extends) coincides with the vehicle width direction of the automobile (not shown). The power plant 1 includes a first vibration isolation device 4 and a second vibration isolation device disposed at both ends in the vehicle width direction (left and right direction in FIG. 1 (a)), that is, at each end on the engine 2 side and the transmission 2 side. It is elastically supported at two points with respect to a vehicle body side frame (not shown) via the device 5.

  In the power plant 1, since the engine 2 is taller than the transmission 3, the inertia main shaft a1 extending in the vehicle width direction is inclined downward from the end on the engine side toward the end on the transmission side. The first vibration isolator 4 and the second anti-vibration device 5 that elastically support the power plant 1 with respect to the inertia main axis a <b> 1 are disposed apart from each other upward. Thereby, the power plant 1 is supported so as to be swingable like a pendulum around a line segment (swing support shaft a <b> 2) connecting the load support points of the first vibration isolation device 4 and the second vibration isolation device 5. The lower part of the power plant 1 is connected to the vehicle body side by a torque rod 6 that extends in the opposite direction to the forward direction of the vehicle, and swinging in the roll direction is restricted. The support structure of the power plant 1 as described above is called a pendulum mount.

  The direction of motion of the power plant 1 (pitch direction, yaw direction, and roll direction) is defined based on the main engine shaft (crank shaft) of the power plant 1. That is, it is perpendicular to the main engine shaft extending in the vehicle width direction (extending in the left-right direction in FIGS. 1A and 1B) (horizontal direction in FIG. 1A and vertical direction in FIG. 1B). The direction around the axis (X-axis) extending to) is the pitch direction. Further, the direction around the axis (Z axis) extending in the vertical direction (FIG. 1 (a) vertical direction, FIG. 1 (b) vertical direction in FIG. 1) orthogonal to the main engine axis is the yaw direction and is parallel to the main engine axis. The direction around the axis extending in the direction (Y axis) is the roll direction.

  The first anti-vibration device 4 and the second anti-vibration device 5 are not liquid-filled anti-vibration devices, but support a load by a vibration-isolating base made of a rubber-like elastic body (so-called solid anti-vibration rubber). )). Further, the first vibration isolator 4 and the second vibration isolator 5 are set so that the spring constants in the vertical direction are different from each other. Note that the spring constants in the vertical direction of the first vibration isolator 4 and the second vibration isolator 5 can be adjusted as appropriate depending on the shape and material of the vibration isolator base as a rubber-like elastic body.

  Next, a vibration experiment of the vehicle 10 in which the power plant 1 is elastically supported by the vehicle body 11 will be described with reference to FIG. FIG. 2 is a schematic diagram schematically showing a vibration experiment of the vehicle 10. In the vibration experiment, the relationship between the vibration transmitted from the road surface G to the vehicle body 11 through the tires (the front wheels 12 and the rear wheels 13) and the suspensions 14 and 15 and the characteristics of the vibration isolation devices 4 and 5 is investigated for the purpose of improving the ride comfort. It is. In this vibration experiment, in the state where the front wheel 12 of the vehicle 10 is placed on the vibration exciter 20, a vibration in the vertical direction (amplitude is ± 0.5 mm or ± 2 mm) is given while sweeping the frequency by the vibration exciter 20. . Then, the detectors 21 and 22 detect the vertical vibration of the vibrator 20 and the vertical vibration of the floor of the vehicle body 11 that affects the riding comfort, respectively.

  Excitation by the vibration exciter 20 corresponds to road surface irregularities and tire uniformity when the vehicle 10 is traveling. This vibration is transmitted from the front wheel 12 to the vehicle body 11 via the suspension 14, and the power plant 1 elastically supported by the vehicle body 11 by the first vibration isolation device 4 and the second vibration isolation device 5 vibrates. The anti-resonant action increases the floor vertical vibration of the vehicle body 11.

  Next, the floor vertical vibration will be described with reference to FIG. FIG. 3 is a schematic diagram showing the relationship between frequency and floor vertical vibration. In FIG. 3, the horizontal axis represents frequency (unit: Hz). The vertical axis represents the vibration level (unit: dB), and represents the ratio of the amplitude of the vehicle body 11 (floor) to the amplitude of the vibrator 20. As shown in FIG. 3, the floor vertical vibration becomes larger at the frequencies f1 and f2 than the vibration of the vibrator 20, and becomes smaller at the frequency f3 (however, f1 <f2 <f3). The frequency f1 is a so-called spring resonance frequency (about 2 Hz), and the frequency f3 is a natural frequency due to the mass of the power plant 1, the damper effect of the first vibration isolator 4 and the second vibration isolator 5. The frequency f2 is due to the antiresonance of the frequency f3. The anti-resonance at the frequency f2 deteriorates the riding comfort of the vehicle 10.

  Next, the floor vertical vibration will be described with reference to FIG. 4 by replacing it with a two-degree-of-freedom system model. FIG. 4 is a two-degree-of-freedom model of the support structure of the power plant 1, and the two mass points of the vehicle body 11 and the power plant 1 are the suspension 14, the first vibration isolation device 4, and the second vibration isolation device 5 (spring). They are lined up in series. The mass of the vehicle body 11 is M1, and the mass of the power plant 1 is M2.

  Note that the influence of the suspension 15 of the rear wheel 13 located away from the power plant 1 can be ignored with respect to the vertical vibration of the power plant 1, so that the suspension 14 of the front wheel 12 supports the front side of the vehicle body 11. be able to. Therefore, the mass M1 of the vehicle body 11 is an equivalent mass on the front side of the vehicle body 11.

The vertical spring constant of the suspension 14 is K1, and the vertical spring constants of the first vibration isolation device 4 and the second vibration isolation device 5 are K2. Note that the spring constant K2 of the first vibration isolation device 4 and the second vibration isolation device 5 is such that the first vibration isolation device 4 and the second vibration isolation device 5 support the power plant 1 in parallel. 4 and the sum (K ₁ + K ₂ ) of the spring constants in the vertical direction of the second vibration isolator 5.

  Since the torque rod 6 installed between the vehicle body 11 and the power plant 1 mainly regulates the swing of the power plant 1 in the roll direction, excitation of vibrations in the vertical direction and the pitch direction of the power plant 1 is performed. Has little effect on suppression. Therefore, in the two-degree-of-freedom model of floor vertical vibration, the influence of the torque rod 6 can be ignored.

  When the equation of motion of the two-degree-of-freedom system is solved, the frequencies f1 and f2 (vibration level> 0 dB) at which the vertical vibration becomes large can be expressed by the following (Expression 1) and (Expression 2), respectively. Further, the frequency f3 (vibration level <0 dB) at which the vertical vibration is reduced can be expressed by the following (Equation 3).

周波数ｆ２における上下振動は乗り心地に影響するため、この周波数ｆ２における上下振動を減殺するように第１防振装置４の車幅方向（パワープラント１の主機関軸方向）のばね定数Ｋ_１Ｙ及び第２防振装置５の車幅方向のばね定数Ｋ_２Ｙを設定する。

Since the vertical vibration at the frequency f2 affects the ride comfort, the spring constant K _{1Y in} the vehicle width direction (the main engine shaft direction of the power plant 1) of the first vibration isolator 4 so as to attenuate the vertical vibration at the frequency f2 and A spring constant _K2Y in the vehicle width direction of the second vibration isolator 5 is set.

  Here, the natural frequency f4 in the vehicle width direction of the power plant 1 elastically supported by the first vibration isolation base 4 and the second vibration isolation base 5 can be expressed by the following (Equation 4).

車体１１の質量（車体１１前部の等価質量）Ｍ１、パワープラント１の質量Ｍ２、サスペンション１４の上下方向のばね定数Ｋ１は既知であるので、ｆ２＝ｆ４となるように、第１防振装置４の上下方向のばね定数Ｋ_１Ｚ及び車幅方向のばね定数Ｋ_１Ｙ、第２防振装置５の車幅方向（Ｙ軸方向）のばね定数Ｋ_２Ｚ及び車幅方向のばね定数Ｋ_２Ｙを設定する。これにより、ピッチ方向の揺動をパワープラント１に生じ易くさせ、パワープラント１の上下方向およびピッチ方向の振動を連成させて、反共振によるパワープラント１の上下方向の振動エネルギーを分散させることができる。なお、第１防振装置４及び第２防振装置５の車幅方向のばね定数Ｋ_１Ｙ，Ｋ_２Ｙは、ゴム状弾性体としての防振基体の形状や材質等によって適宜調整できる。

Since the mass of the vehicle body 11 (equivalent mass at the front of the vehicle body 11) M1, the mass M2 of the power plant 1, and the spring constant K1 in the vertical direction of the suspension 14 are known, the first vibration isolator is set so that f2 = f4. 4, a spring constant K _{1Z in} the vertical direction and a spring constant K _1Y in the vehicle width direction, a spring constant K _{2Z in} the vehicle width direction (Y-axis direction) of the second vibration isolator 5 and a spring constant K _2Y in the vehicle width direction are set. To do. Thereby, the oscillation in the pitch direction is easily generated in the power plant 1, and the vibration in the vertical direction and the pitch direction of the power plant 1 are coupled to disperse the vibration energy in the vertical direction of the power plant 1 due to anti-resonance. Can do. The spring constants K _1Y and K _{2Y in} the vehicle width direction of the first vibration isolator 4 and the second vibration isolator 5 can be adjusted as appropriate depending on the shape and material of the vibration isolator base as a rubber-like elastic body.

  Hereinafter, the present invention will be described specifically by way of examples. The present invention is not limited to these examples.

  5 to 8 are diagrams illustrating measurement results of the vibration level in the vertical direction of the floor. First, a simulation result using a computer (6-DOF vibration-proof support design) will be described with reference to FIGS. These simulations assume that the vehicle 10 is vibrated using the vibrator 20 (see FIG. 2) (amplitude ± 0.5 mm). FIG. 5 is a simulation result of the vibration level in the vertical direction of the floor. In FIG. 5, the horizontal axis represents frequency (unit: Hz). The vertical axis represents the vibration level (unit: dB), and represents the ratio of the amplitude of the vehicle body 11 (floor) to the amplitude of the vibrator 20.

Example 1
In the support structure in the first embodiment shown in FIG. 5, the vertical spring constant K _{1Z of} the first vibration isolator 4 is 100 N / mm, and the vertical spring constant K _{2Z of} the second vibration isolator 5 is 200 N / mm. _Yes (K _2Z / K _1Z = 2), the loss factor of the first vibration isolation device 4 and the second vibration isolation device 5 is 0.2.

(Example 2)
In the support structure in Example 2, the vertical spring constant K _{1Z of} the first vibration isolation device 4 is 80 N / mm, and the vertical spring constant K _{2Z of} the second vibration isolation device 5 is 160 N / mm (K _2Z / K _1Z = 2), the loss factor of the first anti-vibration device 4 and the second anti-vibration device 5 is 0.2.

(Comparative Example 1 and Comparative Example 2)
In the support structure in Comparative Example 1, a liquid-sealed anti-vibration mount is disposed at the position of the first anti-vibration device 4 in place of the first anti-vibration device 4 and the second anti-vibration device 5 is disposed at the second position. A solid anti-vibration rubber is disposed in place of the anti-vibration device 5. That is, Comparative Example 1 is a conventional support structure for a power plant 1 (conventional example disclosed in Patent Document 1). Further, Comparative Example 2 is configured in the same manner as Comparative Example 1 except that the liquid sealed in the liquid chamber of the liquid seal type vibration-proof mount is removed. The loss factor of the liquid-sealed anti-vibration mount and anti-vibration rubber from which the liquid was extracted in Comparative Example 2 was 0.1.

In Example 1 and Example 2, by appropriately setting the spring constant _K1Y in the vehicle width direction of the first vibration isolator 4 and the spring constant _{K2Y in} the vehicle width direction of the second vibration isolator 5, The natural frequency (f4, see FIG. 3) of the power plant 1 in the vehicle width direction was set to about 9 Hz, which is substantially the same as the antiresonance frequency (f2) in Comparative Example 2.

As is apparent from the simulation results shown in FIG. 5, according to Example 1 and Example 2, the vibration level due to antiresonance seen in Comparative Example 2 can be suppressed to the same level as in Comparative Example 1 (conventional example). It was. In addition, compared with Example 1, Example 2 is guessed that the natural frequency of the up-down direction was shifted to the low frequency side by the small amount of the spring constants K _1Z , K _{2Z in} the up-down direction.

  From this simulation result, it became clear that the vertical vibration of the power plant 1 can be damped by a simple structure that does not employ the liquid-sealed anti-vibration mount. This is presumably because the vibration in the pitch direction is easily generated in the power plant 1 and the vibration energy in the vertical direction of the power plant 1 due to anti-resonance can be dispersed. In addition, if the liquid-sealed anti-vibration mount is not used, the increase of the dynamic spring constant in the high frequency range due to the liquid-sealed anti-vibration mount can be prevented, so that the deterioration of the vibration noise performance can be prevented and the ride comfort can be prevented. Performance can be secured.

Further, the first vibration isolator 4 and the second vibration isolator 5 have a frequency axis due to anti-resonance of the vertical vibration of the power plant 1 by setting the natural frequency f4 of the power plant 1 in the vehicle width direction. The peak of the resonance peak appearing above (see Comparative Example 2) is reduced. The natural frequency f4 in the vehicle width direction of the power plant 1 is the vehicle width direction component (K _1Y , K _2Y ) of the spring constants of the first vibration isolation device 4 and the second vibration isolation device 5 and the mass M2 of the power plant 1. Therefore, the design of the first vibration isolation device 4 and the second vibration isolation device 5 can be facilitated.

  Next, the relationship between the loss factor and the vibration level of the first vibration isolator 4 and the second vibration isolator 5 will be described with reference to FIG. FIG. 6 is a simulation result of the vibration level in the vertical direction of the floor. In FIG. 6, the horizontal axis represents frequency (unit: Hz). The vertical axis represents the vibration level (unit: dB), and represents the ratio of the amplitude of the vehicle body 11 (floor) to the amplitude of the vibrator 20.

(Example 3)
In the support structure in Example 3 shown in FIG. 6, the vertical spring constant K _{1Z of} the first vibration isolation device 4 is 100 N / mm, and the vertical spring constant K _{2Z of} the second vibration isolation device 5 is 200 N / mm. Yes (the above characteristics are the same as in the first embodiment), and the loss factor of the first vibration isolator 4 and the second vibration isolator 5 is 0.1.

Example 4
A support structure in Example 4 was obtained in the same manner as in Example 3 except that the loss factor of the first vibration isolator 4 was set to 0.2.

(Example 5)
A support structure in Example 5 was obtained in the same manner as in Example 3 except that the loss factor of the second vibration isolator 5 was set to 0.2. In addition, since the comparative example 1 and the comparative example 2 are the same as what was mentioned above, description is abbreviate | omitted.

  As is apparent from the simulation results shown in FIG. 6, Example 3 was able to disperse the peak of the resonance peak due to anti-resonance, which was found in Comparative Example 2 at a frequency of about 9 Hz, into two. Further, in Example 4 and Example 5, it is clear that the vibration level can be made smaller than that in Example 3 due to the vibration damping characteristics of the first vibration isolation device 4 and the second vibration isolation device 5 represented by the loss factor. It was. From these Examples, it can be seen that the vibration energy in the vertical direction can be attenuated by the vibration damping characteristics of the first vibration isolator 4 and the second vibration isolator 5 to further improve riding comfort performance. The loss factor is set in consideration of the frequency characteristics and temperature characteristics of the first vibration isolation device 4 and the second vibration isolation device 5.

  Next, an experimental result (actual vehicle test result) in which the vehicle 10 is vibrated using the vibrator 20 (see FIG. 2) will be described with reference to FIGS. 7 and 8 show the experimental results of the vibration level in the vertical direction of the floor. FIG. 7 shows the experimental results when the amplitude of the vibrator 20 is ± 0.5 mm, and FIG. 8 shows the experimental results when the amplitude of the vibrator 20 is ± 2.0 mm. 7 and 8, the horizontal axis represents frequency (unit: Hz). The vertical axis represents the vibration level (unit: dB), and represents the ratio of the amplitude of the vehicle body 11 (floor) to the amplitude of the vibrator 20.

(Example 6)
In the support structure in Example 6 shown in FIGS. 7 and 8, the total value (K _1Z + K _2Z ) of the spring constants K _1Z and K _{2Z in} the vertical direction is 273 N / mm, and the vertical direction of the first vibration isolator 4 is vertical spring constant _{K 2Z} ratio of the spring constant _{K 1Z} to the second vibration damping device 5 _(K 2Z _/ K _1Z) is 1.28. The first anti-vibration device 4 has a loss factor of 0.15, and the second anti-vibration device 5 has a loss factor of 0.18. Further, the vehicle width direction of the spring constant _{K 1Y,} the total value of _{K 2Y (K 1Y + K 2Y} ) is 390 N / mm. The ratio of the total value (K _1Y + K _2Y ) of the spring constants K _1Y and K _{2Y in} the vehicle width direction to the total value (K _1Z + K _2Z ) of the vertical spring constants K _1Z and K _2Z is set to 1.43. Yes.

(Example 7)
In the support structure in the seventh embodiment, the total value (K _1Z + K _2Z ) of the vertical spring constants K _1Z and K _2Z is 310 N / mm, and the first vibration isolator 4 has a vertical value corresponding to the vertical spring constant K _1Z . 2 The ratio (K _2Z / K _1Z ) of the spring constant K _{2Z in} the vertical direction of the vibration isolator 5 is 0.96. The loss factors of the first vibration isolation device 4 and the second vibration isolation device 5 are both 0.18. The total value (K _1Y + K _2Y ) of the spring constants K _1Y and K _{2Y in} the vehicle width direction is 438 N / mm. The ratio of the total value (K _1Y + K _2Y ) of the spring constants K _1Y and K _{2Y in} the vehicle width direction to the total value (K _1Z + K _2Z ) of the vertical spring constants K _1Z and K _2Z is set to 1.41. Yes.

(Example 8)
In the support structure in Example 8, the total value (K _1Z + K _2Z ) of the vertical spring constants K _1Z and K _2Z is 427 N / mm, and the first vibration isolator 4 has a vertical value relative to the vertical spring constant K _1Z . 2 The ratio (K _2Z / K _1Z ) of the spring constant K _{2Z in} the vertical direction of the vibration isolator 5 is 1.65. The first anti-vibration device 4 has a loss factor of 0.18, and the second anti-vibration device 5 has a loss factor of 0.20. The total value (K _1Y + K _2Y ) of the spring constants K _1Y and K _{2Y in} the vehicle width direction is 501 N / mm. The ratio of the total value (K _1Y + K _2Y ) of the spring constants K _1Y and K _{2Y in} the vehicle width direction to the total value (K _1Z + K _2Z ) of the vertical spring constants K _1Z and K _2Z is set to 1.18. Yes.

(Comparative Example 3)
The support structure in Comparative Example 3 is a liquid-sealed anti-vibration mount disposed in place of the first anti-vibration device 4 and a rigid anti-vibration rubber disposed in place of the second anti-vibration device 5. That is, Comparative Example 3 is a conventional support structure for power plant 1 (conventional example disclosed in Patent Document 1). The characteristics of the liquid seal type vibration isolation mount and the vibration isolation rubber are as follows. The total value (K _1Z + K _2Z ) of the spring constants K _1Z and K _2Z in the vertical direction is 294 N / mm. vertical spring constant _{K 2Z} ratio of damping rubbers with respect to the spring constant _{K 1Z (K 2Z / K 1Z} ) is 0.84. The loss factor of the liquid ring type anti-vibration mount is 1.10, and the loss factor of the anti-vibration rubber is 0.06. The total value (K _1Y + K _2Y ) of the spring constants K _1Y and K _{2Y in} the vehicle width direction is 154 N / mm. The ratio of the total value (K _1Y + K _2Y ) of the spring constants K _1Y and K _{2Y in} the vehicle width direction to the total value (K _1Z + K _2Z ) of the vertical spring constants K _1Z and K _2Z is set to 0.52. Yes.

(Comparative Example 4)
The support structure in Comparative Example 4 is configured in the same manner as in Comparative Example 3 except that the liquid sealed in the liquid chamber of the liquid seal type vibration-proof mount is removed. The total value (K _1Z + K _2Z ) of the spring constants K _1Z and K _{2Z in} the vertical direction of the liquid-sealed anti-vibration mount and the anti-vibration rubber from which the liquid has been removed is 264 N / mm. The ratio (K _2Z / K _1Z ) of the vertical spring constant K _2Z of the anti-vibration rubber to the vertical spring constant K _1Z of the liquid-sealed anti-vibration mount from which the liquid has been removed is 1.05. The loss factor of the liquid-sealed anti-vibration mount and the anti-vibration rubber from which the liquid has been removed is 0.06. The total value (K _1Y + K _2Y ) of the spring constants K _1Y and K _{2Y in} the vehicle width direction is 181 N / mm. The ratio of the total value (K _1Y + K _2Y ) of the spring constants K _1Y and K _{2Y in} the vehicle width direction to the total value (K _1Z + K _2Z ) of the vertical spring constants K _1Z and K _2Z is set to 0.69. Yes.

The spring constants K _1Y and K _{2Y in} the vehicle width direction of the first vibration isolator 4 and the second vibration isolator 5 in the sixth to eighth embodiments are anti-resonant resonance peaks that appear in the support structure in the fourth comparative example. And the natural frequency f4 in the vehicle width direction of the power plant 1 elastically supported by the first vibration isolator 4 and the second vibration isolator 5 are set to coincide with each other.

As is apparent from the actual vehicle test results shown in FIGS. 7 and 8, according to Examples 6 to 8, the vibration level due to anti-resonance generated in Comparative Example 4 is set to Comparative Example 3 (regardless of the magnitude of the amplitude). It was possible to suppress almost the same as the conventional example). In Example 6, it is _surmised that the natural frequency in the vertical direction is shifted to the lower frequency side by the amount that the total value of the vertical spring constants K _1Z and K _2Z is smaller than that in Example 7. . Further, in Example 8, it is _surmised that the natural frequency in the vertical direction is shifted to the high frequency side as the total value of the vertical spring constants K _1Z and K _2Z is larger than that in Example 7. As described above, even in the actual vehicle test results, it has become clear that the vertical vibration of the power plant 1 can be damped by a simple structure that does not employ the liquid-sealed anti-vibration mount.

Moreover, in the support structure in Example 6 to Example 8, the first vibration isolator 4 and the second vibration isolator 5 have a total value (K _1Z + K _2Z ) of the respective spring constants in the vertical direction. It is set to be smaller than the total value (K _1Y + K _2Y ) of the spring constants in the width direction. That is, the ratio of the total value (K _1Y + K _2Y ) of the spring constants K _1Y and K _{2Y in} the vehicle width direction to the total value (K _1Z + K _2Z ) of the vertical spring constants K _1Z and K _2Z (hereinafter referred to as “aspect ratio”). Is set to a value larger than 1. Thereby, the vertical displacement of the power plant 1 can be easily regulated by the first vibration isolation device 4 and the second vibration isolation device 5. As a result, since the vibration energy in the vertical direction of the power plant 1 due to anti-resonance can be reduced, the vertical vibration of the vehicle body 11 can be attenuated, and the riding comfort of the vehicle 10 can be reliably improved.

  As demonstrated in Examples 6 to 8, it is desirable to set the aspect ratio in the range of 1.1 to 1.5. As the aspect ratio becomes smaller than 1.1, the effect of regulating the vertical displacement of the power plant 1 by the spring component in the vehicle width direction of the first vibration isolator 4 and the second vibration isolator 5 tends to decrease. It is done. As a result, there is a tendency that it is difficult to reduce the vibration energy in the vertical direction of the power plant 1 due to anti-resonance.

  On the other hand, as the aspect ratio becomes larger than 1.5, the spring component in the vehicle width direction of the first vibration isolator 4 and the second vibration isolator 5 tends to make it difficult to excite the swing of the power plant 1 in the pitch direction. Seen. As a result, there is a tendency that it is difficult to reduce the vibration energy in the vertical direction of the power plant 1 due to anti-resonance. As described above, by setting the aspect ratio of the first anti-vibration device 4 and the second anti-vibration device 5 in the range of 1.1 to 1.5, these problems can be prevented, and the vehicle body 11 It is possible to attenuate the vertical vibration and improve the riding comfort of the vehicle 10 with certainty.

  The present invention has been described above based on the embodiments. However, the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention. It can be easily guessed.

  In the above embodiment, both ends of the power plant 1 in the main engine axial direction are supported by the two mounts (the first vibration isolation device 4 and the second vibration isolation device 5) attached to the vehicle body 11, and the vehicle body 11 and the power The case of the pendulum mount method in which the movement of the power plant 1 in the roll direction is suppressed by the torque rod 6 installed between the plant 1 and the plant 1 has been described. However, the present invention is not necessarily limited to this, and can naturally be applied to other mounting methods in which the power plant 1 is suspended horizontally. As another mounting method, for example, an inertia main shaft method can be cited.

  In the inertia main shaft system, both ends of the power plant 1 in the main engine shaft direction are supported by two mounts attached to the vehicle body 11, but the swing support shaft a2 (see FIG. 1 (a)) and the inertia main shaft a1. The two mounts are arranged so that. Furthermore, the movement of the power plant 1 in the roll direction is suppressed by the two mounts arranged before and after the power plant 1. The two mounts arranged before and after the power plant 1 mainly suppress the movement of the power plant 1 in the roll direction, so when considering floor vertical vibration, the influence of the two mounts before and after the power plant 1 is Can be ignored.

  Therefore, in the case of the inertia main shaft method, as in the case of the pendulum mount method described in the above embodiment, it is only necessary to consider two mounts that elastically support both ends of the power plant 1 in the main engine shaft direction. Therefore, although the description is omitted in the above embodiment, the same relationship as in the case of the pendulum mount system described in the above embodiment is also established in the case of the inertial spindle system. As a result, even if the suspension method of the power plant 1 is the inertia main shaft method, the power plant 1 is elastically supported as in the above-described embodiment, so that the swing in the pitch direction can easily occur in the power plant 1, and The vibration energy in the vertical direction of the power plant 1 due to resonance can be dispersed. Thereby, the vertical vibration of the power plant 1 can be damped by a simple structure that does not employ the liquid seal type vibration-proof mount, similarly to the present embodiment.

DESCRIPTION OF SYMBOLS 1 Power plant 4 1st vibration isolator 5 2nd vibration isolator 10 Vehicle 11 Car body

Claims (4)

In the power plant support structure for supporting the power plant in which the main engine shaft is arranged in the vehicle width direction of the vehicle on the vehicle body side via the vibration isolator,
The vibration isolation device includes a first vibration isolation device and a second vibration isolation device that elastically support both sides of the power plant in the vehicle width direction on the vehicle body side,
The first anti-vibration device and the second anti-vibration device are set to have different vertical spring constants and to reduce vertical vibration due to anti-resonance of the power plant in the vehicle width direction. A power plant support structure in which a spring constant is set.   The first anti-vibration device and the second anti-vibration device are arranged in the vehicle width direction of the power plant so as to reduce the peak of the resonance peak appearing on the frequency axis due to anti-resonance of vibration in the vertical direction of the power plant. 2. The power plant support structure according to claim 1, wherein a natural frequency is set.   3. The power plant according to claim 1, wherein the first vibration isolation device and the second vibration isolation device have a vibration suppression characteristic that attenuates vibrations in a vertical direction of the power plant. 4. Support structure.   The first anti-vibration device and the second anti-vibration device are set such that the total value of the spring constants in the vertical direction is smaller than the total value of the spring constants in the vehicle width direction. The power plant support structure according to any one of claims 1 to 3.

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