JPH0332418Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a support structure for a center bearing provided in the intermediate portion of a propeller shaft.

(Prior art) Generally, in F/R type (front engine rear drive type) automobiles, a transmission and a final reduction gear, which are separated in the longitudinal direction, are connected by a propeller shaft to transfer engine rotation to the rear wheels. It is designed to be communicated. By the way, the propeller shaft is connected with several hook joints interposed in the middle in order to absorb the relative displacement between the vehicle body and axle while driving, suppress vibrations to the vehicle body, and smoothly transmit engine rotation. The middle part is supported by a center bearing with an insulator (utility development in 1987).
- such as those described in Publication No. 90831). The generation of muffled noise is reduced by the above-mentioned center bearing insulator.

(Problem that the invention is trying to solve) However, with the conventional center bearing support structure described above, when wind-up occurs when starting, etc. and the final reduction gear tilts significantly, the bending angle of the propeller shaft becomes large and the center bearing support structure becomes unstable. A large secondary couple occurs. The vibration caused by this couple is
It has a frequency of 15 to 30 Hz, and is hardly reduced by the above-mentioned insulators, causing vibrations in the vehicle body through the center bearing (so-called trembling vibrations). One possible countermeasure to this problem is to reduce the dynamic spring constant of the insulator to shift the resonance point, but this would deteriorate the durability of the insulator. Another countermeasure is to increase the damping capacity of the insulator, but
The dynamic spring constant increases above 100Hz, worsening the muffled sound. Therefore, there was a problem in that it was difficult to tune the spring characteristics of the insulator so as to simultaneously reduce the vibrations at the time of starting and the muffled noise during driving. Therefore, an object of the present invention is to increase the degree of freedom in tuning the spring characteristics of the center bearing support structure by utilizing spring characteristics of different systems.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the center bearing support structure according to the present invention has a center bearing support structure fitted with a propeller shaft that transmits driving torque from an engine to a final gear via a joint. A bearing, a bracket surrounding the circumference of the center bearing via a first insulator and having both ends supported by the vehicle body, a second insulator interposed between the vehicle body and the bracket, and a second insulator. The insulator is characterized by defining at least a pair of liquid chambers that communicate with each other.

(Operation) The propeller shaft is rotatably supported by the vehicle body by a center bearing, and smoothly transmits driving torque from the engine to the final gear via the joint. 30~50Hz generating muffled sound
The vibration of the frequency of is caused by the first insulator and the second insulator.
The vibration is generated by one spring of the insulator or the dynamic spring characteristics.15
Vibrations with a frequency of ~30 Hz can be absorbed (attenuated) by the spring or dynamic spring characteristics of the other of the first and second insulators. In this way, by utilizing the dynamic spring characteristics of different systems of springs or liquids, in addition to the vibration damping effect in the frequency range mentioned above, it is possible to lower the vibration transmission rate in a certain frequency range, and to support the center bearing. The degree of freedom in tuning the spring characteristics of the structure can be increased.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. 1 to 4 are diagrams showing a center bearing support structure according to an embodiment of the present invention.

First, to explain the structure, in FIG. 1, 10 is a center bearing support structure;
2 is a two-split type propeller shaft that transmits driving torque from an engine (not shown) to a final gear (not shown). At both ends (not shown) of one propeller shaft 12, a transmission output shaft (not shown) and a final gear input shaft (not shown) are provided.
One of the propeller shafts and the other propeller shaft are connected by a hook joint (not shown). propeller shaft 1
A centering bearing 14 is fitted into the center bearing 14, and a first insulator 2 is disposed between the outer sleeve support member 16 that supports the outer sleeve 14a of the center bearing 14 and the bracket 18.
0 and cushion rubber 22 are interposed.
As shown in FIG. 2, the bracket 18 is composed of two upper and lower members 18a and 18b, and these two members 18a and 18b are secured to each other by bolts 24 and nuts 26 at both ends. A second insulator 40 having a smaller dynamic spring constant than the first insulator 20 is interposed between both ends of the bracket 18 and the vehicle body 28.
A bracket 32 is fixed to the vehicle body 28 by welding or the like, and a second
An inner sleeve 41a of the insulator 40 is fastened and fixed by bolts 34 and nuts 36.

In FIGS. 3 and 4, 42 is an outer sleeve of the second insulator 40, and this outer sleeve 42 is fixed to both ends of the bracket 18 by welding or the like. A liquid chamber communication member 44 is fitted and fixed to the circumference of the inner sleeve 41, and four boss portions 44a are formed at equal intervals in the circumferential direction of the liquid chamber communication member 44. A communication hole 44b whose axes intersect with each other in a cross shape is formed in the boss portion 44a. Liquid chamber communication member 4
Inner sleeve 41 facing communication hole 44b of No. 4
An annular communication groove 41a is formed around the periphery. Four elastic bodies 46 having a wall thickness are provided between the outer periphery between the pair of adjacent boss portions 44a of the liquid chamber communication member 44 and the inner periphery of the outer sleeve 42.
47, 48, 49 are interposed, and liquid chambers 51, 52, 53,
54 are defined. 51 to 54 communicate with each other via the communication hole 44b of the liquid chamber communication member 44 and the communication groove 41a of the inner sleeve 41, respectively.

Next, the effect will be explained.

The propeller shaft 12 has a center bearing 14
It is rotatably supported by the vehicle body 28, and together with the other propeller shaft, drive torque from the engine is smoothly transmitted to the final gear via the hook joint. At this time, if vibrations with a frequency of 30 to 50 Hz occur due to the primary imbalance, the first insulator 20 with a small spring constant
This is blocked by the cushion rubber 22, and muffled noise can be effectively prevented from occurring. In addition, if vibrations with a frequency of 15 to 30 Hz occur due to the angular velocity of the propeller shaft 12 fluctuating due to the bending angle of the hook joint becoming large due to wind-up during startup, etc., the second Each liquid chamber 51 to 54 of the insulator 40
Attenuated by liquid movement between Therefore, the occurrence of the undulating vibration can be effectively prevented. In particular, by defining the four liquid chambers 51 to 54, vibrations in both directions AB in FIG. 3 can be damped.

In this way, in this example, by utilizing the characteristics of two different systems of springs and dynamic springs,
In addition to the vibration damping effect in the frequency range described above, the vibration transmissibility in a certain frequency range can be lowered, and the degree of freedom in tuning the spring characteristics of the center bearing support structure 10 can be greatly increased. In this embodiment, four liquid chambers are defined, but only one pair (two) of upper and lower liquid chambers may be formed to attenuate only important vertical vibrations.

(Effects of the invention) As explained above, according to the invention, there is provided a center bearing fitted to a propeller shaft that transmits driving torque from an engine to a final gear via a joint, and a center bearing that is connected to a first A bracket surrounded by an insulator and supported at both ends by the vehicle body, a second insulator interposed between the vehicle body and the bracket, and at least a pair of fluid chambers communicating with each other are defined in the second insulator. In addition to the vibrations in the frequency range that generate muffled and buzzing noises, the vibration transmission rate in a certain frequency range can be reduced, and the tuning of the spring characteristics of the center bearing support structure can be reduced. The degree of freedom can be increased.

[Brief explanation of the drawing]

1 to 4 are diagrams showing an embodiment of the center bearing support structure according to the present invention, in which FIG. 1 is a sectional view thereof, FIG. 2 is a partial sectional view taken in the direction of the − arrow in FIG. 1, and FIG. is a sectional view of the buffer means, and FIG.
It is a sectional view taken along the - arrow in the figure. 10... Center bearing support structure, 12...
Propeller shaft, 14...center bearing,
14a, 42... Outer sleeve, 16... Outer sleeve support member, 18, 32... Bracket, 18a, 18b... Member, 20... First insulator, 22... Cushion rubber, 24, 3
4...Bolt, 26, 36...Natsuto, 28...
Vehicle body, 40...Second insulator, 41...Inner sleeve, 46-49...Elastic body, 41a...
...Communication groove, 44...Liquid chamber communication member, 44a...Boss portion, 44b...Communication hole, 51-54...Liquid chamber.

Claims (1)

[Scope of utility model registration request] A center bearing fitted to a propeller shaft that transmits driving torque from an engine to a final gear via a joint, and a bracket surrounding the center bearing via a first insulator and having both ends supported by the vehicle body. A center bearing support structure comprising: a second insulator interposed between the vehicle body and the bracket, the second insulator defining at least a pair of fluid chambers that communicate with each other.