JP2957662B2 - Tubular anti-vibration bush - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cylindrical vibration-isolating bush, and more particularly, to a cylindrical vibration-isolating bush having a variable spring constant according to a vibration input.

[Prior art] A tubular vibration-isolating bush is one in which an anti-vibration rubber body is arranged between an outer cylinder and an inner cylinder connected to a vibrating body, and has a feature that the structure is simple and the vibration absorbing ability is excellent. It is frequently used for vibration isolation of various parts of vehicles.

By the way, vehicle vibrations cover a wide range according to the traveling state, and it is desired that both absorption of high frequency minute vibrations and suppression of low frequency large amplitude vibrations be performed well. In view of such a demand, a proposal has recently been made in which a liquid chamber is provided in the vibration-isolating rubber body of the cylindrical vibration-isolating bush, and the damping of particularly large vibration input is suppressed by the action of the sealing liquid.

[Problems to be Solved by the Invention] However, the provision of the liquid chamber has a problem that the structure of the vibration isolating bush is complicated, and a great deal of labor is required for molding and assembling the vibration isolating rubber body.

An object of the present invention is to solve such a problem, and an object of the present invention is to provide a cylindrical anti-vibration bush that can favorably prevent transmission of a wide range of vibration input without causing a complicated structure and difficulty in assembling. I do.

[Means for Solving the Problems] The configuration of the present invention will be described. In a cylindrical vibration-isolating bush in which an anti-vibration rubber body 3 is disposed between an outer cylinder 1 and inner cylinders 2A and 2B,
The anti-vibration rubber body 3 is made of an elastic modulus variable rubber material filled with particles that are polarized when an electric field acts thereon,
The inner circumference of the outer cylinder 1 and the inner cylinders 2A and 2B which face each other via the vibration-proof rubber body 3
Electrodes 4A and 4B for forming an electric field in the vibration-isolating rubber body 3 are provided on the outer periphery, respectively.
A power supply control means 5 for controlling power supply to A and 4B is provided.

[Operation] In the cylindrical vibration-isolating bush having the above configuration, the electrodes 4A and 4B are not energized when a high-frequency minute vibration is input. No electric field is formed in the vibration-proof rubber body 3, and the spring constant of the vibration-proof rubber body 3 is small. As a result, effective absorption of minute vibrations is achieved.

When large vibration of low frequency is input, the above electrodes 4A, 4B
, And an electric field is formed in the rubber vibration insulator 3.
This electric field acts on particles in the rubber material to cause polarization, thereby changing the elastic modulus of the rubber material and increasing the apparent spring constant of the vibration-isolating rubber body 3. Thus, large vibrations can be effectively suppressed and reduced.

[Embodiment] In the figure, the tip of a strut bar 8 is tapered and stepped, and a pair of inner cylinders 2A and 2B are fitted on the outer periphery of the strut bar 8 with their end faces in contact. Inner cylinders 2A and 2B are formed with lead wire insertion grooves 41 communicating both ends and a part of the inner peripheral surface,
Further, the entire outer periphery of the opposed end portion of both inner cylinders 2A and 2B is deleted at a constant depth, and the cylindrical electrode 4B is filled so as to fill these deleted portions.
Is fitted and held.

An outer cylinder 1 is disposed outside the inner cylinders 2A and 2B at a constant distance from the inner cylinders 2A and 2B.
The cylindrical electrode 4A is joined and fixed by facing the electrode 4A.
Is bent and exposed to the outer periphery of the outer cylinder 1. Further, the outer cylinder 1 is formed as a flange portion 11 by bending one end opening edge into an L shape.

A flange is provided at one end between the outer cylinder 1 and the inner cylinders 2A and 2B.
A cylindrical anti-vibration rubber body 3 having a constant thickness and formed with 31 is press-fitted. The vibration-isolating rubber body 3 is made of a rubber material having a variable elastic modulus filled with particles that are polarized when an electric field acts. For example, solid particles such as polycobalt methacrylate are brought into contact with each other in an insulating rubber material such as silicon rubber. It can be made of a rubber material that is densely packed to increase the efficiency. An example of the composition is shown in a separate table. The diameter of the solid particles in the table is 45
It has a water absorption of 12.7 wt% with a thickness of up to 105 μm.
The solid particles are polarized when an electric field acts, and the mutual bonding force increases according to the electric field strength.

The external power source 6 is connected to the electrode 4B through the lead wire insertion groove 41.
One end of a lead wire 61 is connected to the other end, and one end of a lead wire 62 connected to the external power supply 6 via the conduction control switch 5 is connected to the exposed portion of the electrode 4A.

A screw portion 81 is formed at the tip of the strut bar 8, and a holding plate 83 is fixed between the strut bar 8 and the end surface of the inner cylinder 2B by a nut 82 screwed into the screw portion 81.

The anti-vibration bush having such a structure is fixed by press-fitting the outer cylinder 1 into the cylindrical holding portion 71 of the bracket 7 provided on the vehicle frame. At this time, the flange portion 11 comes into contact with the bracket surface.

In the anti-vibration bush having the above structure, when high-frequency micro-vibration such as road noise is input during running of the vehicle, the power supply control switch 5 is opened and power is not supplied to the electrodes 4A and 4B. Thus, no electric field is formed in the vibration-isolating rubber body 3,
The bonding force of the solid particles becomes small, and the spring constant of the vibration-proof rubber body 3 becomes small only by the rubber material. This allows
Micro vibrations are effectively absorbed.

When a large low-frequency vibration such as a harshness vibration is input during running or during cornering, the power supply control switch 5 is closed, and power is supplied to the electrodes 4A and 4B to form an electric field in the vibration-proof rubber body 3. When this electric field acts, the solid particles have an increased bonding force, and the apparent spring constant of the vibration-isolating rubber body 3 increases due to the contribution of the bonding force. Thus, large vibration input is effectively suppressed and reduced. Here, FIG. 2 shows an example of a change in the shear modulus of the vibration-isolating rubber body having the composition shown in the above separate table, and the shear modulus increases in proportion to the applied electric field. In this measurement, the vibration-proof rubber body was press-fitted into one of the U-shaped electrodes, the other plate-shaped electrode was inserted into the middle position of the rubber body, and a voltage was applied. It is calculated from the force required to extract the other electrode.

[Effects of the Invention] As described above, according to the cylindrical vibration-isolating bush of the present invention, the elasticity of the rubber material constituting the vibration-isolating rubber body is changed by controlling the energization of the electrodes, and the exerted spring force Can be freely changed to reliably prevent the transmission of vibrations in a wide range, and the structure of the vibration isolating bush can be prevented from becoming complicated.

[Brief description of the drawings]

FIG. 1 is an overall vertical cross-sectional view of a cylindrical vibration-isolating bush, and FIG. 2 is a diagram showing elastic modulus characteristics of a vibration-isolating rubber body. DESCRIPTION OF SYMBOLS 1 ... Outer cylinder 2A, 2B ... Inner cylinder 3 ... Anti-vibration rubber body 4A, 4B ... Electrode 5 ... Power supply control switch (power supply control means) 6 ... External power supply 61, 62 ... Lead wire 7 ... ... Bracket 8 ... Strut bar

Claims (1)

(57) [Claims] In a cylindrical vibration-isolating bush having an anti-vibration rubber member disposed between an outer cylinder and an inner cylinder, a rubber-elasticity-variable rubber filled with particles that are polarized when an electric field is applied thereto. In addition to being made of a material, electrodes for forming an electric field in the vibration-isolating rubber body are provided on the outer circumference of the outer cylinder and the outer circumference of the inner cylinder facing each other via the vibration-isolating rubber body, and these electrodes are connected to these electrodes in response to vibration input A tubular anti-vibration bush provided with an energization control means for controlling the energization of the cylinder.