JPS61166722A - Mounting device for power unit - Google Patents

Abstract

PURPOSE:To enable oscillation to be reduced by arranging at least one of numbers of mounts to a point which is subjected to the pitching oscillation of a power unit, so as to allow this spring characteristic to coincide with the direction, to which the principal axis of elasticity for low stiffness is subjected to a load cut to oscillation. CONSTITUTION:In a configuration where a power unit 1 which combines an engine 2 with a transmission 3, is supported elastically to a body by mounts 4a-4c which are arranged back and forth, and left and right in regard to the unit, each of the mounts 4a-4c is composed of an outer cylinder 6, an inner cylinder 7, and rubber which is filled and anchored between the outer cylinder 6 and the inner cylinder 7. And an adjustment section 9 is formed at the both sides of the rubber holding the inner cylinder 7 in the mount 4a which is one of the mounts located in the longitudinal direction. And the spring characteristic is set in such a manner that its principal axis l1 of elasticity for high stiffness is to be parallel with the adjustment section 9, its principal axis l2 of elasticity for low stiffness is to be in the direction perpendicular to the adjustment section 9, and the principal axis l2 is allowed to coincide with the direction, to which the mount is subjected to a pitching oscillation of the power unit 1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a mounting device for mounting a power unit to a base, and particularly relates to an improvement in a mounting device installed in a vehicle.

(Prior Art) Conventionally, as such a mounting device, mounts are provided on both sides of the power unit in the longitudinal direction and on both sides in the direction orthogonal to the power unit, and these mounts elastically hold the power unit against the base. It is generally well known that the system is supported by
(See official bulletins, etc.) There are many types of mounts, including those made of rubber and those made using fluid.

(Problem to be solved by the invention) By the way, in a vehicle, the natural frequency of the bounce mode and the natural frequency of the pitching mode of the power unit are close to each other, and the higher the degree of achievement of both modes, the lower the level of vehicle body shake. It is known that this will happen. This is due to the following reasons. In other words, when the vehicle body shakes while driving, the power unit resonates and causes bounce vibration, but if the power unit also causes pitching vibration at the same time as this bounce vibration, the total kinetic energy of the power unit is The energy of the bounce vibration becomes relatively small and the energy of the pitch vibration becomes large. The effect of both vibrations on the car body is that the moment of inertia of the car body is large relative to Nfl, and pitching vibration is smaller than bounce vibration, so the total kinetic energy of the power unit is averaged. The level of

However, the power unit in a conventional vehicle is mainly supported by mounts disposed at positions apart from each other on both sides in the longitudinal direction to prevent pitching vibration.
Pitching rigidity is high. For this reason, the natural frequency of the pitching mode is considerably higher than that of the bounce mode, and the degree of achievement of both modes is currently low.

In addition, in vehicles, especially those with a horizontal power unit, the shape of the power unit itself is asymmetrical with respect to the rotation axis, and the main axis of roll inertia is relatively largely deflected with respect to the rotation axis, so torque fluctuations cause roll vibration and There is a problem in that pitching vibration is significantly excited and the imaging level during idle rotation becomes large.

The present invention has been made in view of these points, and its purpose is to reduce the natural frequency of the pitching mode of the power unit in a vehicle and bring it closer to the natural frequency of the bounce mode, thereby achieving both of these. This aims to reduce vehicle body shake by increasing the degree of achievement of the mode, and also to reduce the vibration level during idling.

(Means for solving the problem) In order to achieve the above object, the solving means of the present invention provides a mounting device having a plurality of mounts that elastically supports a power unit in a vehicle with respect to a base (vehicle body). At least one of the plurality of mounts is arranged at a position that receives pitching vibration of the power unit, and the spring characteristics of this mount are set so that the low-rigidity elastic main shaft matches the direction in which the pitching vibration load of the power unit is received. It is structured as follows.

(Function) With the above configuration, in the present invention, the power unit that is elastically supported on the base by the plurality of mounts has a low rigidity elastic main axis of the mount that is disposed at a position receiving pitching vibration of the power unit among the mounts. By being coincident with the pitching vibration direction, the natural frequency of the pitching mode of the power unit is effectively reduced and becomes close to the natural frequency of the bounce mode.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a vehicle with a horizontally installed power unit. Reference numeral 1 denotes a power unit in which a transmission 3 is connected to an engine 2, and the power unit 1 is on both sides in the longitudinal direction (vehicle width direction). and mounts 4a, 4b, and 4c on both sides in the direction orthogonal thereto (vehicle body longitudinal direction) (mounts on the rear side of the vehicle body are not shown)
These mounts 48 to 4c elastically support the power unit 1 with respect to a vehicle body (not shown) serving as a base.

The mounts 4a to 4C have the same configuration, and to explain the mount 4a on the negative side (right side in the figure) of the power unit 1, as shown in FIG. 2, it is fixed to the bracket 5 on the power unit 1 side. The inner cylinder 7 consists of an outer cylinder 6, an inner cylinder 7 located at the center of the outer cylinder 6, and a rubber 8 filled and fixed between the inner cylinder 7 and the outer cylinder 6. Although not shown, it is connected to a bracket on the vehicle body side via a support shaft.

Here, when the power unit 1 causes pitching vibration near its center of gravity Gl, the mounting positions of the mounts 48 to 4C do not coincide with the center of gravity G position of the power unit 1, so the pitching vibration occurs. It will be subjected to a load due to

The acting direction of the pitching vibration load on each of the mounts 48 to 4C is the tangential direction of a circle passing through each of the mounts 48 to 4C with the center of gravity G of the power unit 1 as the center. In addition, the magnitude of the pitching vibration load at each mount 4a to 4C1 is determined by the center of gravity G of the power unit 1 and each mount 4.
A particularly large pitching vibration load acts on the mounts 4a and 4b on both sides of the power unit 1 in the longitudinal direction in proportion to the distance between them.

As a feature of the present invention, the mount 4a on the longitudinal side of the power unit 1 is provided with recesses 9.9 on both sides of the inner cylinder 7 of the rubber 8, as shown in FIG. The spring characteristics of the mount 4a are such that the high-rigidity elastic main axis 9 is located in the direction parallel to the hollow parts 9, 9, and the low-rigidity elastic main axis 92 is located in the direction orthogonal to the hollow parts 9.9. In addition, the low-rigidity elastic main axis intersection 2 is set to coincide with the direction in which the power unit 1 receives the pitching vibration load (the tangential direction of the circle 93 passing through the mount 4a with the center of gravity G of the power unit 1 as the center).

Therefore, in the above embodiment, the power unit 1
Among the mounts 4a to 4C that elastically support the power unit 1 to the vehicle body, the power unit 1 is mounted on the negative side in the longitudinal direction of the power unit 1.
The spring characteristics of the mount 4a, which is disposed at a position that receives a large amount of pitching vibration, are set to align the low-rigidity elastic main shaft 91 with the direction in which the power unit 1 receives the pitching imaging load. The characteristic i-movement frequency of the pitching mode is effectively reduced by 1J.

For this reason, the natural frequency of the pitching mode of the power unit 1 and the natural frequency of the bouncing mode of the power unit 1, which is at a lower level than the natural frequency, can be brought close to each other, thereby increasing the degree of achievement of both modes. Shake can be reduced.

Furthermore, even if pitching vibration is excited due to torque fluctuations due to the fact that the main roll inertia axis of the power unit 1 is deflected with respect to the rotation axis during idle rotation, the above-mentioned natural vibration of the pitching mode of the power unit 1 As the number decreases, pitching vibration can be absorbed and alleviated to that extent, and the vibration level on the vehicle body side can be reduced.

Figures 3 and 4 show the results of vibration tests conducted on the example of the present invention and the conventional example. Figure 3 shows the measurement results of vehicle body shake, and Figure 4 shows the vibration transmission from the power unit to the vehicle body. The results of the measurement of the ratio are shown. Incidentally, the example of the present invention referred to here refers to the longitudinal direction of the power unit as in the above embodiment.
Low rigidity elastic main shaft of mount 4a placed on the side! Q2 is made to match the direction in which the pitching vibration load of the power unit 1 is received.
The high-rigidity elastic principal axes 9+ of the two are aligned in the vertical direction.

From Fig. 3, in the case of the example of the present invention, the frequency at which the vehicle body shake is maximum due to pitching resonance is approximately 14.5Hz).
is lower than that frequency of the conventional example (approximately 17H2), and the frequency at which vehicle body shake is maximum due to roll resonance (approximately 10
．． 5 Hz), and that the maximum value of vehicle body shake due to roll resonance is significantly smaller (approximately 0.5×10'+u++/s) than in the conventional example.

Moreover, from FIG. 4, in the case of the example of the present invention, the vibration transmissibility in the idle rotation range (region 1 where the frequency is 20 Hz or more) and the area adjacent thereto is significantly smaller than that of the conventional example. I understand that.

In the above embodiment, the spring characteristics of only the mount 4a disposed on the negative side of the power unit 1 in the longitudinal direction were set so that the low-rigidity elastic principal axis fiz coincided with the direction in which the power unit 1 received the pitching vibration load. However, the present invention
The mount 4 may be placed in other positions as necessary, taking into consideration the relationship with the roll rigidity of the power unit 1.
The spring characteristics of mounts b and 4c may be set similarly to those of the mount 4a.

Furthermore, the positions of the plurality of mounts 4a to 4C that elastically support the power unit 1 do not need to be limited to those in the above embodiments. In short, the above mount 48
At least one of ~4C is disposed at a position where it receives the pitching vibration of the power unit 1, and the spring characteristics of this mount are set so that the low-rigidity elastic main shaft coincides with the direction in which the pitching vibration load of the power unit 1 is received. All you have to do is do it.

(Effects of the Invention) As described above, according to the power unit mounting device of the present invention, at least one of the plurality of mounts that elastically supports the power unit with respect to the vehicle body is disposed at a position receiving pitching vibration of the power unit, and By aligning the low-rigidity elastic main axis of this mount with the direction in which the power unit receives the pitching vibration load, the natural frequency of the pitching mode of the power unit can be effectively lowered to approach the natural frequency of the bounce mode. Therefore, it is possible to increase the degree of achievement of both modes and reduce vehicle body shake.In addition, it is possible to effectively suppress the pitching vibration of the power unit excited by torque fluctuations from being transmitted to the vehicle body, thereby reducing vibration during idling. It is possible to reduce the level.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a schematic diagram showing the positional relationship between the power unit and the mount, FIG. 2 is a vertical side view of the mount, and FIG. 3 shows the measurement results of vehicle body shake. 4 is a diagram showing the measurement results of the vibration transmission rate from the power unit to the vehicle body. 1...Power unit, 4a, 4b, 4c...
Mount, 92...Low rigidity elastic main shaft.

Claims (1)

[Claims] (1) A mounting device having a plurality of mounts that elastically supports a power unit with respect to a base,
At least one of the plurality of mounts is arranged at a position receiving pitching vibration of the power unit,
A mounting device for a power unit, characterized in that the spring characteristics of the mount are set so that the low-rigidity elastic main axis coincides with the direction in which the power unit receives a pitching vibration load.