JPH0246407B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a power unit support device for an automobile;
In particular, it relates to a power unit support device for a motor vehicle having a front wheel drive transverse engine.

Vibrations that occur in a power unit, which is an integral assembly of an engine and a transmission, include vibrations applied from the road surface through the wheels and vibrations from the engine itself. The main vibration noise caused by these excitation forces is the vertical vibration of the power unit, and when it approaches the unsprung frequency of the suspension mechanism, a resonance phenomenon occurs, causing a so-called car shake that causes the vehicle body to vibrate greatly. As a device for absorbing vertical vibration of a power unit, there is a device described in Japanese Patent Laid-Open No. 157625/1983 for use in rear wheel drive vehicles.
In this device, a power unit is supported by a plurality of insulators, and another insulator with a fluid damping function is arranged to absorb vertical vibrations of the power unit. However, in order to fully utilize the function of an insulator with a fluid damping function, it is desirable to place the insulator at a position where the vibration of the power unit is most intense; however, in the above-mentioned known device,
Not enough consideration has been given to making the insulator perform its functions to its full potential.

The vertical vibration of the power unit is a combination of the force input from the road surface and the excitation force of the engine as described above, but the engine excitation force acts on the center of the engine, away from the center of gravity of the power unit. This causes pitting and bouncing around the center of gravity of the power unit, so vertical vibration tends to be greatest at the engine-side end of the power unit. The present invention focuses on this point, and aims to effectively reduce vibration transmission to the vehicle body and suppress the occurrence of noise and car shake.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a power unit support device capable of sufficiently damping and absorbing vertical vibrations of a power unit in a front-wheel drive vehicle with a transverse engine.

A structural feature of the present invention is that, in a transverse engine type front-wheel drive vehicle, a first insulator that supports the power unit on both sides of the transmission at a position closer to the transmission than the center of gravity of the power unit; A second insulator supports the power unit on a side opposite to the first insulator, and at least one of the second insulators is disposed near an end of the engine opposite to the transmission, and the engine Only the second insulator disposed near the end is a fluid insulator, and the fluid insulator communicates fluid chambers disposed in the vertical direction through an orifice,
The purpose is to damp the vertical vibrations of the power unit. Preferably, the mounting direction of the fluid insulator is inclined so that the upper side faces outward in the lateral direction of the vehicle body. In a preferred embodiment of the present invention, one of the second insulators having a fluid damping function is arranged near the position of the largest amplitude on the excitation source side of the power unit. For this purpose, each static spring constant of the first insulator is k ₁ , k ₂ . . .
Let the insulators be K ₁ , K _{2 .} . . , and the distances in the power unit axial direction between these insulators and the center of gravity of the power unit be l ₁ , l _{2 .} . . L ₁ , respectively.
When L ₂ ..., the configuration is made so that the relationship Σk _i l _i >ΣK _{i Li} holds at least in the low frequency range where car shake is a problem, and the structure is designed so that the relationship Σk i l i >ΣK i Li It is sufficient to increase the amplitude at the end on the engine side. The fluid insulator of the present invention has a structure that can most effectively attenuate and absorb vertical vibrations, and is installed so as to fully exhibit its functions. Therefore, the present invention provides a power unit support device that has a sufficient damping function and can sufficiently reduce pitting and car shake of the power unit. Further, according to the present invention, vertical vibrations of the power unit can be sufficiently damped and absorbed at lower cost and more effectively than when all insulators are fluid insulators.

Embodiments of the present invention will be described below with reference to the drawings.

Referring to FIGS. 1-3, a power unit 10 consists of an engine 12 and a transmission 14, which are integrally assembled. The engine 12 is a so-called horizontal engine installed so that the rotating shaft of a crankshaft (not shown) is oriented transversely to the vehicle body, and its cylinder axis is arranged vertically. The transmission 14 is connected laterally to the engine 12. The power unit 10 is supported by a first insulator 16 and a second insulator 26 in an engine room 17 formed at the front of the vehicle body. The first insulator 16 is provided at the front and rear of the transmission 14 side with respect to the center of gravity G of the power unit 10, and includes a bracket 18 fixed to the transmission 14 and a bracket 22 on a subframe 20 of the vehicle body attached to the lower part of the engine room 17. It is installed between the two to absorb vibrations in the rotational direction of the power unit that occur due to engine torque fluctuations. The first insulator is made of ordinary elastic rubber, and the relative displacement between the two brackets is absorbed only by deformation of the elastic rubber. The second insulator 26 has a first insulator with respect to the center of gravity G of the power unit 10.
It is provided near the end of the engine on the opposite side of the insulator 16. Further, a roll stopper 24 is provided between the end of the engine and the vehicle body.
The roll stopper 24 is located on the side wall 2 of the vehicle engine compartment.
The rod 24a is attached to the bracket 30 attached to the
The engine 1 is made of elastic rubber supported by
It is inserted into an upwardly open U-shaped bracket 32 attached to 2. This roll stopper 24
The elastic rubber is disposed with an appropriate gap between it and the bottom surface of the bracket 32, so it does not provide resistance to normal vertical vibrations of the power unit, and the side wall of the bracket 32 provides resistance to roll vibrations. The roll of the power unit is suppressed by contacting and deforming the power unit. Further, the second insulator 26 is provided below the engine 12 and is fixed via an attachment piece 40 between a bracket 36 attached to the subframe 80 and a bracket 38 attached to the engine 12. 1st
The entire weight of the power unit 10 is supported by the insulator 16. The insulator 26 is
As an example is shown in FIG. 4, it has a fluid damping function by sealing incompressible fluid inside, and has an upper cover 50 fixed to the engine 10 and a subframe 20 of the vehicle body, and a bottom plate 52 fitted thereto. A cylindrical rubber 54 is disposed between the top cover 50 and the bottom plate 52. The upper lid 50 is provided with an orifice member 58 having an orifice 56 of a suitable diameter. A groove 60 is provided on the inner peripheral surface of the upper lid 50 above the orifice member 58, and a diaphragm 62 is inserted and fixed into this groove 60. Above this diaphragm 62 is a top lid 50.
The air chamber 64 is opened by this diaphragm 62.
An upper oil chamber 66 is formed below the diaphragm 62 by the diaphragm 62 and the orifice member 58. Further, below the orifice member 58, this orifice member 58, a rubber 5
4 and the bottom plate 52 form a lower oil chamber 68,
Fluid, ie, hydraulic oil, flows through these upper and lower oil chambers 66, 68.
enclosed within. When the rubber 54 is compressed in the vertical direction (damping action axis direction) in FIG.
When the external force is removed and the upper lid 50 is pushed back upward by the elastic force of the rubber 54, it flows from the upper oil chamber 66 into the lower oil chamber 68.
will flow again. That is, this insulator functions as an engine mount using the rubber 54, and also viscously damps vibrations due to the resistance when passing through the orifice.

As shown in FIG. 1, the second insulator 26 is installed in an upward direction and is inclined outward in the lateral direction of the vehicle body. That is, with this arrangement, when pitching the power unit 10, the damping action axis of the second insulator can always be made substantially coincident with the vibration direction at its mounting position. The second insulator 26 also includes an annular flange 69 integrally formed with the lower lid 52 and an annular flange 70 integrally formed with the upper lid 50 so as to surround the outer periphery of the annular flange 69.
and has a rubber 54a formed integrally with the rubber 54 and bonded to the flange 70 between the two and serving as a stopper in the roll direction. The rubber 54a and the roll stopper 24 form a stopper against large roll vibrations peculiar to front wheel drive.

Referring again to FIG. 1, the power unit 10
The positional relationship of the insulators 16, 26 with respect to the center of gravity G is as follows: When viewed in the axial direction of the power unit 10 (in the lateral direction of the vehicle body), the distances from the center of gravity G to the two first insulators 16, 16 are l ₁ , l ₂ , and the center of gravity G Letting L be the distance from to the second insulator 26, let k ₁ and k ₂ be the static spring constants of the first insulator for a frequency of 10 to 20 Hz, and let K be that of the second insulator, then KL<k ₁ l ₁ +k ₂ l It is configured to satisfy _{the following} relationship. As a result, the amplitude of vibrations generated by the acceleration force of the power unit 10 from the road surface also increases as it moves leftward in FIG. 1, reaching its maximum at the left end (end on the engine side). In this example, the second insulator 26 is attached near the left end of the power unit 10, so that the vibration damping function of the second insulator 26 can be exhibited most effectively. In addition, power unit 10
Since the vibration includes a rotational vibration component around the center of gravity G, the vibration direction is inclined slightly outward at the lower left end in FIG. Therefore, in this example, the second insulator 26 is tilted outward so that its axis of action substantially coincides with the direction of vibration, so that the function of the insulator is fully exhibited.

In this case, when there is a relatively large amplitude and low frequency vibration of about 10Hz to 20Hz, mainly due to the force transmitted from the road surface through the wheels, the fluid in the second insulator 26 passes through the orifice 56 to the upper and lower oil chambers. 66 and 68, the vibration is attenuated by the flow resistance caused by the orifice, and the amplitude of this vibration is small against relatively high frequency vibrations of about 100 Hz or more, mainly caused by engine excitation force, so the fluid reciprocates. Instead, vibrations are absorbed by the rubber 54. Therefore, in any of the above cases, vibration transmission to the vehicle body can be sufficiently suppressed, and the occurrence of car shake can be suppressed.

[Brief explanation of drawings]

Fig. 1 is a schematic side view of a power unit equipped with a support device according to the present invention, Fig. 2 is a plan view thereof, Fig. 3 is an end view seen from the right side of Fig. 1, and Fig. 4 is a second insulator. FIG. Explanation of symbols, 10... Power unit, 12...
...Engine, 14...Transmission, 16...First insulator, 24, 26...Second insulator, 50...Top lid, 52...Bottom plate, 54...Rubber, 62...Diaphragm.

Claims (1)

[Scope of Claims] 1. A front-wheel-drive vehicle in which a power unit consisting of a transverse engine and a transmission connected to the engine in a position transverse to the vehicle body is supported in an engine compartment provided at the front of the vehicle body. In this power unit support device, a first insulator supporting the power unit on both sides of the transmission on the transmission side with respect to the center of gravity of the power unit, and a first insulator on the opposite side of the first insulator with respect to the center of gravity of the power unit. Only the second insulator disposed near the end of the engine is a fluid insulator, and the fluid insulator communicates fluid chambers disposed in the vertical direction through an orifice to damp vibrations in the vertical direction of the power unit, Let k _i be the static spring constant of the first insulator, and K _i be the static spring constant of the second insulator.
And when the distances in the axial direction of the power unit between the second insulator and the center of gravity of the power unit are respectively l _i and L _i , the relationship Σk _i l _i >ΣK _i L _i holds at least in the low frequency vibration region. A power unit support device for an automobile, characterized in that it is configured as follows. 2. The power unit support device for an automobile according to item 1, wherein the mounting direction of the fluid insulator is inclined outward in the lateral direction of the vehicle with respect to the vertical direction.