JPS6360257B2 - - Google Patents

Description

[Detailed Description of the Invention] Γ Industrial Application Field The present invention relates to a power unit mounting device, and in particular to a main power unit that supports the mass of a power unit that is a combination of an engine body, a transmission, etc. The present invention relates to a mounting device that includes a mount and a sub power unit mount that mainly restricts the swinging of a power unit.

Γ Prior Art In this type of mounting device, a buffer rod is used as a sub power unit mount.This buffer rod has a pair of elastic bodies at both ends of a connecting member, and one elastic body is placed on the side of the power unit and the other is placed on the side of the power unit. An elastic body is attached to the vehicle body. In this way, the buffer rod installed between the power unit and the vehicle body can have a buffering function and restrict the swinging of the power unit by the elastic body. The elastic body also has the function of reducing the transmission of power unit vibrations to the vehicle body, but this vibration absorption function is not perfect, and some of the vibrations are transmitted to the vehicle body, causing the vehicle to move. This was contributing to the muffled noise in the room. By the way, as described above, the buffer rod is constructed by attaching elastic bodies to both ends of the connecting member, and the connecting member as a mass body performs natural vibration due to the spring action of the elastic body. Therefore, when the power unit vibrates in a certain frequency range, the vibration of the connecting member is damped relative to the power unit vibration, and when the power unit vibrates in a certain frequency range, the connecting member resonates with the power unit vibration and the vibration is amplified. Put it away. Therefore, in the case of conventional mounting devices, as shown in Japanese Patent Application Laid-Open No. 56-90725, the vibration damping function of the connecting member is used, and by adjusting the mass of the connecting member appropriately, the vibration is applied to the vehicle body through the buffer rod. Some devices are designed to attenuate power unit vibrations in the frequency range that cause muffled noise transmitted to the engine.

However, in the vicinity of the low frequency side of the vibration damping region of the buffer load, there is a frequency characteristic as indicated by the broken line in Figure 1.
As shown in (A), a resonance region (B) where vibration is amplified is set. Therefore, even if the vibration damping region is set to the frequency region that causes muffled sound and vibration damping in this frequency region is attempted, the resonance region (B) will cause the muffled sound to occur until now. There was a fear that the amplification of frequency ranges that did not pose a problem would cause new muffled sounds.

Γ Purpose of the Invention In view of the conventional situation, the present invention suppresses the amplification amount of the resonance region appearing in the buffer as a sub power unit mount to a low level.
It is an object of the present invention to provide a mounting device for a power unit that prevents or reduces newly generated muffled noise.

Γ Structure of the Invention In order to achieve the above object, the present invention provides a main power unit mount which mainly receives the static load of the power unit between the engine body and the vehicle body, one of which is mounted on the power unit side and the other mounted on the vehicle body side. In the power unit mounting device, the power unit mounting device includes a sub power unit mount, which has first and second elastic bodies connected by a connecting member, and mainly controls rocking of the power unit. A mass body is attached to the auxiliary power unit mount via an elastic member, and a resonance region of a dynamic damper constituted by these elastic members and the mass body is set to a resonance region of the sub power unit mount itself. be.

Γ Embodiments Examples of the present invention will be described in detail below with reference to the drawings.

That is, FIG. 2 shows a mounting device 1 showing one embodiment of the present invention, and the explanation will be given by taking the rear mount portion as an example. 2 is the main power unit mount,
This main power unit mount 2 includes a bracket 4 fixed to the power unit 3 and a vehicle body frame 5.
It is arranged between the power unit 3 and the power unit 3, and is designed to mainly receive the static load of the power unit 3. Reference numeral 6 designates a buffer rod as an auxiliary power unit mount. This buffer rod 6 is disposed between an auxiliary bracket 7 protruding from the bracket 4 and a dash panel 8 serving as the vehicle body, and is mainly used to control the swinging of the power unit 3. roll displacement, etc.). The buffer rod 6 is shown in FIGS. 3 and 4.
As shown in the figure, first and second
Elastic bodies 11 and 11a are provided, and these first and second elastic bodies 11 and 11a are connected to the connecting member 1.
The outer cylinders 12 and 12a fixed to the outer cylinder 1
Inner cylinder 13, 1 provided concentrically within 2, 12a
3a, and an elastic member 1 loaded between these inner and outer cylinders.
4, 14a, and the first elastic member 11 is connected to the sub bracket 7 via bolts 15, 15a (see FIG. 2) inserted into the respective inner cylinders 13, 13a.
Second, the second elastic body 11a is attached to the dash panel 8. (In addition, the first elastic body 1
1 may be attached to the dash panel 8, and the second elastic body 11a may be attached to the sub bracket 7. ) Also, the connecting member 10 is formed by superposing a first member 10a having a first elastic body 11 fixed thereon and a second member 10b having a second elastic body 11a fixed thereon, which are each formed into a cross-sectional shape. 1. Fasten the second members 10a and 10b with the bolt 1
6. It is constructed by fixing with a nut 16a. Note that the first and second members 10a, 10
The length between the bolts 6 and 6b can be adjusted by making the holes 17 of the first member 10a, through which the bolts 16 are inserted, into elongated holes, thereby facilitating the installation of the buffer rods 6. By the way, the connection member 10
and the first and second elastic bodies 11, 11a.
The spring constant is adjusted in advance as appropriate, and the vibration damping range exerted by the buffer rod 6 is set in the frequency range that causes muffled noise in the vehicle interior.

Here, in this embodiment, the connecting member 10
An elastic member 2 such as rubber (outside the first member 10a)
A mass body 21 is attached to the dynamic damper 2 through the elastic member 20 and the mass body 21.
It consists of 2. In the dynamic damper 22 configured in this way, the mass body 24 is vibrated with the vibration of the connecting member 10 of the buffer rod 6. When the dynamic damper 22 is resonated with the vibration of the connecting member 10, , the mass body 21 vibrates with an opposite phase to the connecting member 10 via the connecting member 20, and has a function of damping the vibration of the connecting member 10. Therefore, in this embodiment, by appropriately setting the mass of the mass body 21 and the spring constant of the elastic member 20, the resonance region of the dynamic damper 22 can be adjusted so that the buffer rod 6 is amplified and vibrated by the power unit vibration. It is limited to coincide with the resonance region.

The functions of the mounting device 1 according to the present invention having the above configuration will be explained using the model shown in FIG. 5. That is, this model shows the actual mounting state in which the main power unit mount 2 and the buffer rod 6 are installed side by side between the power unit 3 and the vehicle body 5, 8, and the first and second elastic bodies 11, 11a of the buffer rod 6 are mounted side by side. Let the spring constant of the dynamic damper 22 be "k", the loss factor be "l", the mass of the connecting member 10 be "m", the spring constant of the elastic member 20 of the dynamic damper 22 be "kd", and the loss factor be "ld", The mass of the mass body 21 is expressed as "md". Further, the spring constant of the main power unit mount 2 is expressed as " _kE ". With the buffer rod 6 modeled in this way (excluding the main power unit mount 2), the displacement excitation (displacement x) on the power unit 3 side acts on the vehicle bodies 5 and 8 via the buffer rod 6. The result is the following equation (1).

F=k・ [(1-l ² )・(1-w ² -md/kd)2l・ld]+j[2・l・
(1‐w ²・md/kd)+ld(1‐l ² )]/[2・(1‐l・ld)‐
w ² {m＋md／k＋2md／kd}＋w ⁴・m・md／k・kd〕＋j
・[2・(l+ld)‐w ² {2・l・md/kd+(m+md)・ld/k}
]・x...(1) However, j=√−1, x=Xcoswt, and w is the angular frequency.

Here, the resonance frequency of the buffer rod 6 determined by the spring constant "k" of the first and second elastic bodies 11, 11a and the mass "m" of the connecting member 10, and the spring constant "kd" of the elastic member 20. Since the resonance frequency of the dynamic damper 22 determined by the mass "md" of the mass body 21 and the mass "md" of the mass body 21 are set to be approximately the same, the frequency characteristic C at this time is as shown by the solid line in FIG. become. In addition, in the same figure, the frequency characteristic C' shown by the two-dot chain line is the first and second elastic bodies 11, 1.
1a and the loss factor of the elastic member are taken into consideration.

Therefore, as is clear from FIG. 6, the dynamic damper 22 is affected by the buffer load 6.
In _{the frequency characteristic C of}
is expressed by the following equation, ignoring the loss factor for simplicity.

Furthermore, in the frequency range of peak P ₂ or higher, the phase of the force with respect to the excitation displacement is reversed.

Here, if we consider the spring constant "k _E " (k _E >k) of the main power unit mount 2 as shown in _FIG . Since the phase is opposite to that of the excitation input F _E from the unit mount 2, the forces cancel each other out and muffled noise is reduced as shown in FIG. This effect becomes more pronounced as the spring constant ``k <sub>'</sub> ' of the first and second elastic bodies 11 and 11a of the buffer rod 6 increases relative to the spring constant ``KE'' of the main power unit mount 2. Incidentally, if the spring constant "k" is made larger than the spring constant "k _E " in this way, the deterioration region that occurs in the low frequency direction will also increase with respect to the effective region shown in Fig. 6, causing problems. However, in the present invention, since the deterioration margin is reduced by providing the dynamic damper 22, the spring constant "k" of the first and second elastic bodies 11, 11a is set to the main power unit mount 2. The spring constant `` _kE '' can be made relatively large, and the vibration damping effect transmitted from the power unit main body 3 to the vehicle bodies 5 and 8 can be increased. Frequency characteristics (A) shown in Figure 6
This is the case of only the main power unit mount 2.

By the way, the spring constant "k" of buffer rod 6,
When applying the mass "m", the spring constant "kd" of the dynamic damper 22, and the mass "md" to the actual mounting device 1, _p1 = 40 to 90 Hz _p2 = 80 to 120 Hz _T = 70 to 90 Hz are appropriate. Therefore, the values may be set in the following ranges: k=4 to 20 Kg/mm n=0.5 to 2.0 Kg kd=2 to 10 Kg/mm d=0.1 to 0.3 Kg.

Furthermore, as is clear from these values, the mass "md" of the mass body 21 can be relatively light at 0.1 to 0.3Kg, and can be easily configured without significantly increasing the vehicle weight. Muffled sounds can be effectively reduced.

FIG. 7 shows another embodiment of the present invention, in which a dynamic damper 22 is attached to the outside of the outer cylinder 12 of the first elastic body 1, and the outer cylinder 12 is attached to a buffer rod 6.
Since it vibrates together with the connecting member 10, the same effects as those of the embodiments shown in FIGS. 3 and 4 can be achieved. Note that the dynamic damper 22 is the second
A similar effect can be obtained even if the elastic body 11a is attached to the outside of the outer cylinder 12a.

Γ Effects of the Invention As explained above, in the power unit mounting device of the present invention, a dynamic damper is provided in the sub power unit mount which is installed in parallel with the main power unit mount between the power unit main body and the vehicle body. Since the resonance region of this dynamic damper is set to the resonance region of the auxiliary power unit mount itself, the frequency region on the power unit main body side that is amplified by the auxiliary power unit mount is affected by the dynamic damper effect. can be reduced. Therefore, by reducing the vibrations that are amplified in the resonance region of the sub power unit mount with the dynamic damper, the vibration damping function of the sub power unit mount in areas other than the resonance region can be reduced. This has the excellent effect of significantly reducing vibrations transmitted to the vehicle body and suppressing muffled noise generated inside the vehicle interior.

[Brief explanation of drawings]

Fig. 1 is a frequency characteristic diagram of a sub power unit mount used in a conventional mounting device, Fig. 2 is a main part configuration diagram showing an embodiment of the mounting device of the present invention, and Fig. 3 is a diagram of the main part used in the present invention. 4 is a rear view of the auxiliary power unit mount shown in FIG. 3, FIG. 5 is a model diagram of the mounting device shown in FIG. 2, and FIG. 6 is a side view of the auxiliary power unit mount shown in FIG. FIG. 7 is a rear view of a sub power unit mount showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Mounting device, 2... Main power unit mount, 3... Power unit, 5, 8... Vehicle body, 6... Sub power unit mount, 10... Connection member, 11... First elastic body, 11a... Second elastic body , 20... Elastic member, 21... Mass body, 22... Dynamic damper.

Claims (1)

[Claims] 1. Between the power unit and the vehicle body, there is a main power unit mount that mainly receives the static load of the power unit, and a first and second mount mounted on the power unit side, one on the vehicle body side, and connected by a connecting member. In a mounting device for a power unit including a sub power unit mount having an elastic body and mainly regulating rocking of the power unit, a mass body is attached to the sub power unit mount via an elastic member, A power unit mounting device characterized in that a resonance region of a dynamic damper constituted by an elastic member and a mass body is set to a resonance region of the sub power unit mount itself.