JPH05112793A - Electroviscous fluid - Google Patents

Abstract

PURPOSE:To obtain an electroviscous fluid which can control the actuation of a hermetically sealed device electrically reliably, does not disturb the actuation condition even after repeated actuation of the device, and gives a hermetically seald device of smooth and reproducible actuation. CONSTITUTION:An electroviscous fluid to be filled in a hermetically sealed device. The fluid comprises dispersed phase particles and an insulating dispersion medium and is deaerated. The dispersed phase particles include those of silica, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrorheological fluid, and more specifically to a clutch, a brake, an engine mount, a damper, a valve, a shock absorber,
The present invention relates to an electrorheological fluid that can be effectively used in various devices such as actuators, and in particular, in a sealed device.

[0002]

2. Description of the Related Art An electrorheological fluid is, for example, a fluid obtained by dispersing and suspending dispersed phase particles in an insulating dispersion medium, and its rheological or flow property is a viscoplastic type due to an electric field change. It is known as a fluid that exhibits a so-called Winslow effect, in which the viscosity remarkably rises when an external electric field is applied and large shear stress is induced, when the external electric field is applied. Since the Winslow effect has a characteristic of quick response, the electrorheological fluid having the Winslow effect can be applied to clutches, brakes, engine mounts, dampers, valves, shock absorbers,
Application to various devices such as actuators and electrorheological fluid inkjet has been attempted.

As the electrorheological fluid, it is known that cellulose, starch, silica gel, ion exchange resin and the like are dispersed in insulating oil such as silicone oil, diphenyl chloride and trans oil. Further, in recent years, a fluid using organic semiconductor particles such as poly (acene-quinone) as a dispersed phase (Japanese Patent Laid-Open No. 61-216202), a conductive thin film layer and an electrically insulating layer around the organic solid particles are mainly formed. A fluid in which dielectric particles having a three-layer structure in which a thin film layer is formed is used as dispersed phase particles (Japanese Patent Laid-Open No. 63-97794), and a conductive composition in which conductive particles such as carbon black are dispersed in a resin. A fluid (Japanese Patent Application Laid-Open No. 1-236291) using powder of the product as dispersed phase particles has been proposed.

[0004]

However, when the inventors of the present application conducted a study for putting these electrorheological fluid-operated devices into practical use, the conventional electrorheological fluid was sealed in a sealed device. Due to the presence of dissolved gas and bubbles in the electrorheological fluid, the electrorheological fluid is effective even if the electrorheological fluid is deteriorated due to partial discharge during the operation of the device or the electric field is changed to the sealed device. It was found that the device did not work and the smooth operation of the device was hindered. Further, when the device is repeatedly operated, the device may not operate with good reproducibility, and there is a problem that deterioration in repeated use characteristics of the device is recognized.

Accordingly, it is an object of the present invention to provide an electrorheological fluid that overcomes the above-mentioned problems of the prior art and that facilitates the operation of a sealed device in which the electrorheological fluid is enclosed in the device.

[0006]

The inventors of the present invention have found that the above object can be achieved by using a degassed electrorheological fluid as the electrorheological fluid enclosed in the sealed device, and the present invention has been made. Arrived

The present invention relates to an electrorheological fluid which is composed of dispersed phase particles and an insulating dispersion medium and is deaerated.

The degassing referred to in the present invention is a treatment so that dissolved gas, bubbles and the like do not substantially exist in the electrorheological fluid, for example, leaving the electrorheological fluid under reduced pressure,
Examples of the method include removing dissolved gas and bubbles by stirring or applying vibration.

As a specific method of degassing, the disperse phase particles and the insulating dispersion medium are mixed to prepare an electrorheological fluid, and / or the prepared electrorheological fluid is stirred or vibrated. Method of degassing under reduced pressure, method of encapsulating electrorheological fluid in device and degassing under reduced pressure, and sealing, method of depressurizing device encapsulation part in device and then injecting electrorheological fluid and sealing , A method of immersing the device in an electrorheological fluid and then taking out the device and sealing it. The combined use of these degassing methods is preferable because the electrorheological fluid can be degassed more effectively. As the degassing condition, it is preferable to perform the depressurization under a reduced pressure of 600 torr or less while vibrating or stirring the electrorheological fluid, and particularly preferably under a reduced pressure of 100 torr or less. Further, in order to perform degassing more effectively, degassing under heating can be performed.

The dispersed phase particles constituting the electrorheological fluid that can be used in the present invention are dielectric particles directly involved in the expression of the electrorheological effect. Examples of such dielectric particles include organic particles having a hydrophilic group such as starch, cellulose and ion exchange resins; hydrophilic inorganic particles such as silica and alumina; conductive thin film layers centering on organic solid particles. And a composite dielectric particle such as particles having a three-layer structure in which an electrically insulating thin film layer is formed, particles having a thin insulating film formed on the surface of conductive particles such as aluminum; carbon black in resin, etc. Conductive composition in which the conductive particles are dispersed; organic semiconductor particles such as poly (acene-quinone); and ferroelectric particles such as barium titanate and lithium tartrate.

The insulating dispersion medium that constitutes the electrorheological fluid that can be used in the present invention is not particularly limited as long as it is an insulating liquid that does not dissolve the dispersed phase particles, and examples thereof include polydimethylsiloxane and polyphenylmethyl. Silicone oil such as siloxane; liquid paraffin, decane, dodecane, methylnaphthalene, dimethylnaphthalene, ethylnaphthalene, biphenyl, decalin, hydrocarbon such as partially hydrogenated triphenyl; ether compound such as biphenyl ether; chlorobenzene, dichlorobenzene, Trichlorobenzene, bromobenzene, dibromobenzene,
Chloronaphthalene, dichloronaphthalene, bromonaphthalene, chlorobiphenyl, dichlorobiphenyl, trichlorobiphenyl, bromobiphenyl, chlorodiphenylmethane, dichlorodiphenylmethane, trichlorodiphenylmethane, bromodiphenylmethane, chlorodecane,
Halogenated hydrocarbons such as dichlorodecane, trichlorodecane, bromodecane, chlorododecane, dichlorododecane, bromododecane; halogenated diphenyl ether compounds such as chlorodiphenyl ether, dichlorodiphenyl ether, trichlorodiphenyl ether, bromodiphenyl ether; Daifloyl (manufactured by Daikin Industries, Ltd.), Fluoride such as demnum (manufactured by Daikin Industries, Ltd.); ester compounds such as dioctyl phthalate, trioctyl trimellitate, dibutyl sebacate, and the like, and one or more of them can be used.

The electrorheological fluid used in the present invention is easily obtained by mixing the dispersed phase particles with an insulating dispersion medium and dispersing / suspending the dispersed phase particles in the insulating dispersion medium.

In the present invention, in order to improve the dispersibility of the dispersed phase particles in the dispersion medium, adjust the viscosity of the electrorheological fluid, or improve the shear stress, for example, a surfactant, a polymer dispersant, a polymer thickener, etc. Various additives can be added to the fluid.

The closed device preferably operated by the electrorheological fluid of the present invention has a structure in which the electrorheological fluid enclosed in the device does not come into contact with the outside air, and the electrorheological fluid mechanically outputs electrical input. There is no particular limitation as long as it is a device that can be converted into. As such a sealed device, for example, an actuator (JP-A-48-58295), a clutch (JP-A-53-8466), a torque transmission (EP178078A1) and the like have been proposed.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

[0016]

【Example】

[Example 1] 5 equipped with a stirrer, a reflux condenser and a thermometer
2.4 liters of water was charged into a 4-liter separable flask of 4 liters, and 32.0 g of Kuraray Poval PVA-205 (polyvinyl alcohol; Kuraray Co., Ltd.) was added and dissolved, and then 500 g of styrene and industrial divinyl were added. Benzene (a mixture of 55% by weight of divinylbenzene and 35% by weight of ethylstyrene; manufactured by Wako Pure Chemical Industries, Ltd.) 10
A mixture consisting of 0 g and 8 g of azobisisobutyronitrile was added. Then, the contents in the flask were dispersed at a stirring speed of 600 rpm, and polymerization was carried out at 80 ° C. for 8 hours. The obtained solid substance was separated by filtration, washed thoroughly with water, and then dried at 80 ° C. for 12 hours using a hot air drier to obtain 573 g of a spherical polymer suspension.

2 equipped with stirrer, thermometer and dropping funnel
A 0 liter four-necked separable flask was charged with 500 g of the polymerization suspension obtained by the above-mentioned polymerization reaction, and then,
5 kg of 98% by weight concentrated sulfuric acid was added to obtain a uniform dispersion liquid.
After raising the temperature of the reaction mixture to 80 ° C., the mixture was heated and stirred at the same temperature for 24 hours to carry out a sulfonation reaction. Then, the reaction mixture was poured into water at 0 ° C., filtered and washed with water / acetone. The solid obtained was neutralized with 2 liters of a 10 wt% sodium hydroxide aqueous solution, and then thoroughly washed with water. Then, using a vacuum dryer, it was dried at 80 ° C. for 10 hours to obtain 900 g of a dispersed phase particle composed of a spherical sulfonated polymer, and the humidity was adjusted to a water content of 2% by weight.

80 g of the dispersed phase particles are added to 200 g of Shin-Etsu Silicone Oil KF96-20CS (dimethyl silicone oil; manufactured by Shin-Etsu Chemical Co., Ltd.) and 50 torr.
The electrorheological fluid 28A was prepared by stirring and dispersing for 30 minutes while maintaining the reduced pressure of r.

The adjusted electrorheological fluid 28A was injected into the hermetically sealed device 60 shown in FIG. 7 while keeping the fluid sealing portion under a reduced pressure of 600 torr. After injection, electrorheological fluid 28
A was degassed under a reduced pressure of 20 torr for 3 hours to encapsulate the electrorheological fluid 28A in the device.

The sealed device 60 will be described below.

The sealed device 60 is a device for electrically controlling the speed of a table moved by a pneumatic cylinder by using an electrorheological fluid, and has a drive cylinder 1 and a control cylinder 2. The drive cylinder 1 and the control cylinder 2 are each composed of a rodless cylinder,
It is arranged in parallel between the pair of end blocks 3 and 4. The drive cylinder 1 includes a cylinder tube 5, a pair of pistons 6 movably provided in the cylinder tube 5, and a piston rod 7 connecting both pistons 6, and the piston 6 forms a pair of pistons in the cylinder tube 5. The fluid chambers 8 and 9 are defined. A sliding ring 10 and a packing 11 are fitted around the outer circumference of each piston 6, and cushion bodies 12 are attached to both ends of the piston rod 7.

The control cylinder 2 is provided with a cylinder tube 13, a pair of pistons 14 movably provided in the cylinder tube 13, and a piston rod 15 connecting both pistons 14, and the piston 14 allows the cylinder tube 13 to move. A pair of fluid chambers 16 and 17 are defined in the space 13. A sliding ring 18 and a packing 19 are fitted around the outer circumference of each piston 14, and cushion bodies 20 are attached to both ends of the piston rod 15.

A pair of input ports 21 and 22 are provided in the end block 3, and one input port 21 communicates with one fluid chamber 8 of the drive cylinder 1. The communication pipe 23 is installed between both end blocks 3 and 4, and the other input port 22 is connected to the other fluid chamber 9 via the communication pipe 23. Then, by switching the switching valve (not shown), the compressor (not shown)
When the compressive fluid is supplied from one to the one fluid chamber 8 via the one input port 21, the piston 6 of the drive cylinder 1 is moved to the left. Further, when the compressive fluid is supplied from the compressor to the other fluid chamber 9 via the other input port 22 by switching the switching valve, the piston 6 is moved to the right.

The communication pipe 26 is the both end blocks 3 described above.
A communication passage 27 is provided which is provided between the four ports and which forms a closed circuit for communicating the fluid chambers 16 and 17 of the control cylinder 2 including the communication pipe 26. Incompressible fluid 28
Is both the fluid chambers 16 and 17 of the control cylinder 2 and the communication passage 27.
The incompressible fluid 28, which is filled with the liquid, has a property that its viscosity changes in proportion to the magnitude of the electric field.

A connecting device 29 constituting a connecting means is provided between the drive cylinder 1 and the control cylinder 2 and has a piston 6 of the drive cylinder 1 and a piston 1 of the control cylinder 2.
4 and 4 are linked so that they can be linked. This connecting device 29
A slider 30 movably fitted into the cylinder tube 5 of the drive cylinder 1, a slider 31 movably fitted into the cylinder tube 13 of the control cylinder 2, and a drive cylinder for connecting both sliders 30 and 31. 1 and a control cylinder 2 and a moving member 32 as a connecting body that is disposed across the control cylinder 2. The pair of tubular bodies 33 and 34 are fitted in both sliders 30 and 31, and the sliding cylinders 35 and 36 and the scraper 37 are provided on the inner peripheral surfaces thereof.
・ 38 are provided respectively.

A plurality of piston-side magnets 39 are arranged between the pistons 6 of the drive cylinder 1 via a plurality of yokes 40. A plurality of slider-side magnets are provided on the inner surface of the slider 30 so as to face the piston-side magnets 39. The magnet 41 is arranged via a plurality of yokes 42.
The plurality of piston-side magnets 43 are used for the control cylinder 2
Are arranged between the pistons 14 of FIG. 1 through a plurality of yokes 44 so as to face the piston side magnet 43.
A plurality of slider-side magnets 4 are provided on the inner surface of the slider 31.
5 are arranged via a plurality of yokes 46. The pistons 6 and 14 of both cylinders 1 and 2 are attached to the sliders 30 and 31 and the moving member 3 by the attraction of the piston side magnets 39 and 43 and the slider side magnets 41 and 45.
It is connected via 2 via interlocking.

The one end block 3 is provided with a flow rate adjusting device 47 for adjusting the flow rate, and the incompressible fluid flowing in and out of the fluid chambers 16 and 17 of the control cylinder 2 from the communication passage 27 is provided. Adjust 28 flow rate. And
In the present embodiment, as the flow rate adjusting device 47, an electric field adjusting / applying device 47A for adjusting and applying an electric field to the incompressible fluid 28 is provided. This electric field adjustment application device 4
7A is a cylindrical electrode 49 arranged in the communication passage 27 via an insulator 48, and a predetermined gap 5 is formed in the cylindrical electrode 49.
It is composed of a rod-shaped electrode 52 disposed in the communication passage 27 via an insulator 51 so as to be positioned at 0. The magnitude of the electric field is changed by increasing or decreasing the voltage applied to the electrodes 49 and 52 via the lead wire 53, and the viscosity of the incompressible fluid 28 passing through the gap 50 between the electrodes 49 and 52 is changed. ,, proportional to the magnitude of the electric field.

Next, the operation of the speed control device for the drive cylinder 1 configured as described above will be described.

By switching the switching valve, either one of the input ports 21.2 from the compressor is selected.
When a compressive fluid is supplied to the fluid chamber 8 or the fluid chamber 9 of the drive cylinder 1 via the piston 2, the piston 6 of the drive cylinder 1
Are moved to the left or right. As the drive cylinder 1 and the piston 6 move, the slider 30 of the interlocking device 29
The piston 14 of the control cylinder 2 is integrally moved in the same direction via 31 and the moving member 32.
The fluid chambers 16 and 17 of the control cylinder 2 along with the movement of
A flow of incompressible fluid 28 occurs in between.

At this time, when the voltage applied to both electrodes 49/52 of the electric field adjustment applying device 47A is increased / decreased, the magnitude of the electric field is changed so that the incompressible fluid flowing in the gap 50 between the electrodes 49/52 is changed. The viscosity of 28 is increased or decreased in proportion to the magnitude of the electric field, and the braking force of the control cylinder 2 is increased or decreased. That is, when the voltage applied to both electrodes 49 and 52 increases, the viscosity of the incompressible fluid 28 increases, the flow rate of the incompressible fluid 28 passing through the gap 50 decreases, and the braking force of the control cylinder 2 increases. As a result, the speed of the drive cylinder 1 becomes slow. On the contrary, when the applied voltage decreases, the viscosity of the incompressible fluid 28 decreases and the flow rate through the gap 50 increases, the braking force of the control cylinder 2 decreases, and the speed of the drive cylinder 1 increases. . Therefore, the control speed of the drive cylinder 1 operated by the compressible fluid can be continuously and accurately controlled by the electric signal. By reducing the gap 50, the flow rate of the incompressible fluid 28 can be almost eliminated and the state can be brought close to the locked state. In the first embodiment,
As the incompressible fluid 28, the electrorheological fluid 28A
Is used.

An electrorheological fluid 28A is used as the incompressible fluid 28. As described above, the electrorheological fluid 28A is injected while keeping the fluid sealing portion under a reduced pressure of 600 torr, and after the injection, the electrorheological fluid 28A is injected. 28A is 20to
Using the sealed device 60a that was degassed under reduced pressure of rr for 3 hours and then sealed, a test was performed on the moving speed characteristics of the table with respect to the applied voltage and the characteristics after the repeated operation.

The measurement result shows that the applied voltage is 0 as shown in FIG.
Table movement speed is 600mm for changes of ~ 5kV
It was possible to control over a wide range from around / sec to almost stopped state. Also, in repeated tests 5000 times and 10
Control was possible up to 000 times without deterioration of characteristics.

A test was conducted on the reproducibility of the moving speed characteristics using the above-mentioned sealed device 60a.

As shown in FIG. 5, the measurement result shows that the speed control range is wide and the measured value of the table moving speed varies little with respect to the applied voltage, and control can be performed with good reproducibility.

Example 2 80 g of dispersed phase particles obtained by the same production method as in Example 1 was used as Shin-Etsu Silicone Oil KF9.
An electrorheological fluid 28B was prepared by heating 200 g of 6-20CS (dimethyl silicone oil; manufactured by Shin-Etsu Chemical Co., Ltd.) under a reduced pressure of 100 torr while heating to 50 ° C. and stirring for 30 minutes for dispersion.

In the same sealed device 60 as in Example 1,
The electrorheological fluid 28B was injected as the incompressible fluid 28 while keeping the fluid-filled portion under a reduced pressure of 600 torr.

After the injection, the electrorheological fluid 28B is added to 20 torr.
After degassing for 3 hours under reduced pressure of r, the electrorheological fluid 28B was enclosed in the device.

Using the hermetically sealed device 60b in which the electrorheological fluid 28B is enclosed, the moving speed characteristic of the table with respect to the applied voltage and the characteristic after repeated operation are tested as in the first embodiment.

The measurement results are shown in FIG.
The table moving speed could be controlled over a wide range with respect to the applied voltage, as in the measurement result. In the repeated test, the characteristics could be controlled up to 5000 times and 10000 times without deterioration of characteristics.

Example 3 80 g of dispersed phase particles obtained by the same production method as in Example 1 was used as Shin-Etsu Silicone Oil KF9.
An electrorheological fluid 28C was prepared by stirring and dispersing in 200 g of 6-20CS (dimethyl silicone oil; manufactured by Shin-Etsu Chemical Co., Ltd.) for 30 minutes.

In the sealed device 60 similar to that of the first embodiment,
As the non-compressible fluid 28, the electrorheological fluid 28C was poured while keeping the fluid-filled portion at normal pressure. After that, the electrorheological fluid 28C was degassed under a reduced pressure of 20 torr for 3 hours to encapsulate the electrorheological fluid 28C in the device.

Using the hermetically sealed device 60c in which the electrorheological fluid 28C is enclosed, the moving speed characteristics of the table with respect to the applied voltage and the characteristics after the repeated operation are tested as in the first embodiment.

The measurement results are as shown in FIG.
Up to 5,000 times, the table moving speed could be controlled over a wide range with respect to the applied voltage as in the measurement result of Example 1, but after 10,000 times, the table moving speed could be controlled sufficiently low in the high applied voltage range. Deterioration of the property of not being possible was recognized.

[Embodiment 4] As the non-compressible fluid 28, the electrorheological fluid 28C prepared in Embodiment 3 was poured into the same sealed device 60 as in Embodiment 1 while keeping the fluid-filled portion at normal pressure. After that, the electrorheological fluid 28G is charged with
Degassing was performed under a reduced pressure of orr for 3 hours to encapsulate the electrorheological fluid 28C in the device.

Using the hermetically sealed device 60d in which the electrorheological fluid 28C is enclosed, the moving speed characteristics of the table with respect to the applied voltage and the characteristics after repeated operation are tested in the same manner as in the first embodiment.

As shown in FIG. 4, the measurement results showed good control characteristics at the initial stage, but deterioration of the characteristics was observed after 1000 times and 5000 times.

[Comparative Example 1] As the non-compressible fluid 28, the electrorheological fluid 28C prepared in Example 3 was poured into the same sealed device 60 as in Example 1 while keeping the fluid-filled portion at normal pressure. The electrorheological fluid 28C was enclosed in the device.

Using the sealed device 60e in which the electrorheological fluid 28C is enclosed, the moving speed characteristics of the table with respect to the applied voltage and the characteristics after repeated operation, and the moving speed characteristics are reproduced, as in the first embodiment. The sex was tested.

The measurement results of the table moving speed characteristics with respect to the applied voltage and the characteristics after the repeated operation are as follows.
Poor control characteristics were exhibited from the initial stage, and the characteristics deteriorated with each passing, and after about 100 times, dielectric breakdown occurred in the high applied voltage range, making it unusable.

Further, as shown in FIG. 6, the measurement result of the reproducibility of the moving speed characteristic shows that the speed control range is insufficient in the low speed range and the measured value has a large variation in the high applied voltage range. Was scarce.

[0051]

By using the electrorheological fluid of the present invention enclosed in a sealed device, the operation of the device can be reliably controlled by an electric input, and the operating condition is disturbed even when the operation of the device is repeated. There is no. This makes it possible to obtain a sealed device that operates smoothly and has good reproducibility.

[Brief description of drawings]

FIG. 1 is a graph showing a moving speed of a table with respect to an applied voltage of a sealed device of the present invention.

FIG. 2 is a graph showing the moving speed of the table with respect to the applied voltage of the sealed device of the present invention.

FIG. 3 is a graph showing the moving speed of the table with respect to the applied voltage of the sealed device of the present invention.

FIG. 4 is a graph showing the moving speed of the table with respect to the applied voltage of the sealed device of the present invention.

FIG. 5 is a graph showing the moving speed of the table with respect to the applied voltage of the sealed device of the present invention.

FIG. 6 is a graph showing the moving speed of the table with respect to the applied voltage of the sealed device of the comparative example.

FIG. 7 is a cross-sectional view of a sealed device used in an embodiment of the present invention.

[Explanation of symbols]

 28A Electrorheological fluid 28B Electrorheological fluid 28C Electrorheological fluid

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C10M 151: 02) C10N 20:00 Z 8217-4H 20:06 Z 8217-4H 40:08 40: 14 70:00 (72) Inventor Kazutoshi Ito 3005 Hayasaki, Kitayama, Komaki City, Aichi Prefecture CK Day Co., Ltd. (72) Inventor Uematsu ▲ Eiji ▼ 3005 Hayasaki, Kitayama, Komaki City, Aichi Prefecture In the company

Claims (7)

[Claims] 1. An electrorheological fluid comprising dispersed phase particles and an insulating dispersion medium, which is deaerated. 2. The electrorheological fluid according to claim 1, wherein deaeration is performed under reduced pressure. 3. Degassing is performed by adding vibration or stirring to 60
The electrorheological fluid according to claim 1, which is performed under a reduced pressure of 0 torr or less. 4. The electrorheological fluid according to claim 3, wherein deaeration is performed under heating. 5. The electrorheological property according to claim 1, 2 or 3, wherein deaeration is carried out when and / or after adjusting the electrorheological fluid by mixing dispersed phase particles and an insulating dispersion medium. fluid. 6. The electrorheological fluid according to claim 1, 2 or 3, wherein deaeration is performed when the electrorheological fluid is enclosed in a device operated by the electrorheological fluid. 7. Degassing, when and / or after adjusting the electrorheological fluid by mixing dispersed phase particles and an insulating dispersion medium,
The electrorheological fluid according to claim 1, 2 or 3, which is performed when the electrorheological fluid is enclosed in a device that operates with the electrorheological fluid.