Electroviscous fluid

Details Electroviscous fluid Electroviscous fluid

1993-03-24

1995-02-07

Wu, Shean

Compositions

Liquid crystal compositions

252 73, 252 74, 252 75, 252570, 428 1, C09K 1952, C09K 500, H01B 324

Patent

active

053873700

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL BACKGROUND

The present invention relates to an electroviscous fluid for electrically controlling vibration control machines and devices such as variable damper, engine mount, bearing damper, clutch, valve, shock absorber, precision machine, accoustic machine, etc. and also for display element.


BACKGROUND TECHNIQUE

Electroviscous fluid, in which viscosity of fluid changes when voltage is applied, has been known since many years. Early study on electroviscous fluid was concentrated on a system containing liquid only, while electroviscous fluid of solid dispersion system was developed by Winslow et al.
In such electroviscous fluid, solid particles, polarizing agent, etc. are dispersed in electrically insulating fluid such as mineral oil, synthetic oil, etc., and it is necessary to uniformly disperse solid particles in the electrically insulating fluid to obtain the effect. Even when dispersing agent is used, solid particles are likely to precipitate and this often leads to the decrease of electroviscous effect and unstable property and also to obstruction of various parts of machines. Also, there are problems such as friction wearing of machine parts and decrease of electroviscous effect at the temperature lower than room temperature.
In the past, it has been reported that electroviscous effect is obtained by azomethine liquid crystal under the presence of electric field (Jpn. J. Appl. Phys. 17 (1978), p. 1525). The present inventors have found, during study on application of liquid crystal as electroviscous fluid for machines devices such as variable damper, engine mount, bearing damper, clutch, valve, shock absorber, etc., and that azomethine type liquid crystal has low electroviscous effect, and the effect is further decreased when it is in contact with atmospheric air, thus being not suitable for the use in machines and devices.
The electroviscous fluid comprising nematic liquid crystal has responsiveness of several to several tens of msec., and much higher responsiveness is required depending upon the machine system where electroviscous fluid is used.
It is an object of the present invention to provide an electroviscous fluid, which has high and stable electroviscous effect and wide application temperature range and is to be used for vibration control machines and devices such as variable damper, engine mount, bearing damper, clutch valve, shock absorber, precision machine, accoustic machine, etc. and also for display element.


DISCLOSURE OF THE INVENTION

The electroviscous fluid of the present invention is used for vibration control machines and devices such as variable damper, engine mount, bearing damper, clutch, valve, shock absorber, precision machine, accoustic machines, and also for display element, and it contains liquid crystal substance as principal component.
The electroviscous fluid of the present invention has liquid crystal substance as principal component, and antioxidant and/or metal corrosion inhibitor are added to it.
Further, the electroviscous fluid of the present invention has nematic liquid crystal substance having positive dielectric anisotropy as principal component.
Also, the electroviscous fluid of the present invention has ferroelectric liquid crystal substance as principal component.
Further, the electroviscous fluid of the present invention has liquid crystal or electrically insulating fluid containing liquid crystal as dispersion medium and has solid particles as dispersoid.
In general, liquid crystal has anisotropy and, despite of the fact that it is liquid, it has crystalline property. Because of its dipole moment, it is oriented in a certain direction under the presence of electric field, and theological change occurs due to particle arrangement. Thus, apparent viscosity is increased. That is, under the presence of electric field, resistance occurs against the flow passing between the electrodes, and molecules are bound to each other by electrostatic attractive force. As the result, higher resistance occurs and this increases viscosity.
However, when elect

REFERENCES:
patent: 5075023 (1991-12-01), Fukuyama et al.
patent: 5087382 (1992-02-01), Ishino et al.
patent: 5160451 (1992-11-01), Eidenschink

Affiliated with

Also associated with

Rating

Electroviscous fluid does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Electroviscous fluid, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electroviscous fluid will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1108758