Shaft sealing device and valve structure using the same

A shaft sealing device switches a sealing state and an unsealing state of a fluid, with high sealing performance maintained, because no abrasion accompanies movement of a sealing material or a sealing member, enabling feeding a fluid at a predetermined flow rate, and adjusts the expanding rate of the sealing material with the quantity of an external electric signal and accordingly adjusts the contact face pressure to enable controlling the amount of leakage of the fluid highly precisely, so that it can be used for all applications. The shaft sealing device includes a shaft sealing body formed of a macromolecular material and made expansible or contractible, or deformable, through external electrostimuli applied to a shaft sealing portion disposed in a device body, and flow passages disposed in the shaft sealing portion for feeding the fluid leaked due to the expansion or contraction, or the deformation, of the shaft sealing body.

BACKGROUND OF THE INVENTION

I. Technical Field

The present invention relates to a shaft sealing device for shaft-sealing a fluid using a sealing member and, particularly, to a shaft sealing device using an electro stimuli-responsive macromolecular material and to a valve structure using the same.

II. Description of the Related Art

Generally, in the case of sealing a fluid in a container at all times, a shaft sealing device using a sealing member is utilized. The shaft sealing device is intended to seal the flow of the fluid via the sealing member. As the sealing member of the shaft sealing device, an annular O-ring or packing substantially circular in cross section, for example, is used in order to seal a wide variety of fluids including air, water, oil and gas. The sealing member is required to have high sealing performance because the principal function thereof is to seal the fluids.

For this reason, the sealing member is axially attached to a groove of a substantially rectangular shape in cross section formed within the same plane in the radial direction of a shaft or hole of one of members in the shaft sealing device and, when attaining a seal by pressure of contact with the other of the members in the shaft sealing device, is compressed by the shape of the groove. It is therefore required to have a compression allowance. After the assemblage of the shaft sealing device, the O-ring, for example, is compressed via the compression allowance to produce a repulsion force and, by the repulsion force, fulfills contact surface pressure sealability to attain a shaft seal.

In addition, the O-ring is generally made from one of various kinds of synthetic rubber materials. In order to fulfill an appropriate compression stress within a range in which extraordinary deformation is not induced, the material is required to have a prescribed low compression set and further satisfy characteristics including antiweatherability, abrasion resistance, heat resistance, cold resistance, oil resistance and chemical resistance. In addition, since O-rings are used in shaft sealing devices over a wide variety of fields including fields of automobiles, constructing machines, airplanes, office automation equipment and industrial instruments, for example, the material for the O-rings is selected to have an appropriate compression allowance in accordance with an intended field (purpose) and, even when being used in either a state accompanying the movement of a shaft sealing portion or a stationary state not accompanying the movement of the shaft sealing portion, fulfills durability, insertability and pressing crack prevention, not to mention securement of a shaft-sealing function. Thus, an ordinary shaft sealing device aims first at enhancing a sealing function with a sealing member, such as an O-ring. Generally, therefore, a sealing region of the sealing member or fluid is determined at a prescribed location. An apparatus having such a sealing device embedded therein has a complicated internal structure.

Assuming now that it is necessary to switch the sealing region to an unsealing region, a section of attachment of a sealing member or housing in the sealing region has to be provided with a separate moving mechanism in order to move the sealing region. The moving mechanism includes a screw feed mechanism, a piston-cylinder mechanism and a rotating mechanism, for example. In order to operate these mechanisms, it is necessary to use some power means, such as human power, electricity, air, hydraulic pressure, spring, etc.

On the other hand, not a sealing mechanism, but a valve using a so-called artificial muscle and having no complicated power means is disclosed (refer to Japanese Patent No. 3,501,216, for example). This valve uses an artificial muscle as a valving element and deforms the valving element per se to enable opening and closing a flow path. The valve disclosed in the Document uses as the valving element the artificial muscle formed of an electrostrictive elastic polymer film and deforms the valving element through a voltage ON-OFF operation to bring the valving element into contact with and separation from a valve seat, thereby opening and closing the flow path. The artificial muscle in this valve is called an EPAM (Electroactive Polymer Artificial Muscle) comprising a thin rubber-like macromolecular film (elastomer) and elastic electrodes sandwiching the film, in which voltage is applied between the electrodes to elongate the macromolecular film in a plane direction (to diameter-enlarge it in a circumferential direction).

SUMMARY OF THE INVENTION

However, the case where the shaft sealing device is provided with a moving mechanism or power means in order to switch the sealing region to the unsealing region has entailed a problem that the device becomes complicated in structure and large in entire size. For this reason, the device has possibly been increased in weight and manufacturing cost. In addition, since switching between the sealed state and the unsealed state has accompanied mutual contact and sliding motion among parts constituting the moving mechanism, the contact and sliding motion has possibly caused the parts constituting the moving mechanism and the sliding members to abrade away. Furthermore, since a seal material is moved in a state of contact with and pressure application to a counterpart sealing member within the sealing region, abrasion accompanying the sliding motion has been induced. When a sealing portion including an O-ring has induced abrasion over the entire circumference thereof, fluid leakage is liable to generate due to the pressure reduction at or damage on a contact portion and, in this case, abrasion has further been induced due to external factors including a coarse sliding surface and insufficient lubrication. Moreover, the fluid leakage is liable to generate even when the sliding surface of the O-ring has been abraded away and, when the sliding surface of the O-ring has had scratches, abrasion is further been induced. Particularly, in the case where the motion speed of the moving mechanism has been rapid, where the movement has been made in an eccentric state, where the plane roughness of the sliding surface has been large or where the lubrication has been insufficient, the seal material has possibly been twisted.

Furthermore, since a noise is possibly generated due to the contact or sliding motion of the seal material, sealing member or moving mechanism or since a new task of using a lubricant in order to prevent this noise or abrasion is possibly necessitated, the shaft sealing device has entailed a problem that the reliability thereof at the time of sealing is lowered or that the durability life thereof is considerably shortened.

In addition, though the shaft sealing device is configured so as to fulfill high sealing performance through the securement of precision in plane coarseness of the sealing member in the sealing region, through the attainment of sealing the fluid by the pressure of contact of the seal material with the counterpart member induced in consequence of compressing the compression allowance and through the increase in pressure of contact (self-sealing function) due to the compression of the compression allowance in addition to the deformation of the seal material accompanying the compression, thereby fulfilling contact surface pressure higher than the fluid pressure, it has generally been known that even in the case of the shaft sealing device, it is difficult to completely prevent fluid leakage because a phenomenon of entraining the fluid accompanying the movement of the sealing portion occurs. Furthermore, since an acceptable range of the amount of fluid leakage at the time of shaft sealing has been set in accordance with an intended purpose of a shaft sealing device and since the shaft sealing device is generally required to perform shaft seal while maintaining the amount of fluid leakage within the set acceptable range, the amount of fluid leakage becomes difficult to control.

On the other hand, though Patent Document 1 uses the EPAM as the valving element to eliminate any complicated power mechanism, since the valving element per se constitutes the EPAM and since the fluid pressure is received on the pressure-receiving area of the entire EPAM at the time of fluid sealing, the EPAM is required to have both large compression strength and large sealing power. In addition, since it is necessary to provide a separate sealing mechanism in a main body and prepare a valve seat portion for seating, the application of the EPAM to the valving element per se is irrationalistic because the strength resistance and stress characteristics accompanying deformation the EPAM has are not utilized as-is. Particularly, Patent Document 1 neither has any idea or suggestion in respect of the point of the present inventors' observation that an EPAM is applied to a shaft sealing structure per se nor has any idea or suggestion with respect to the fact that an increase and decrease in shaft sealing power is subtly adjusted with high precision by the function of the EPAM to utilize a fluid leakage phenomenon including minute leakage.

The present inventors have reached the development of the present invention as a consequence of keen studies made in view of the conventional state of affairs described above. The object of the present invention is to provide a shaft sealing device with a simple internal structure that switches a sealing state and an unsealing state of a fluid, with high sealing performance maintained, because of no abrasion accompanying the movement of a sealing material or a sealing member, thereby enabling feeding a fluid at a predetermined flow rate, and adjusts the expanding rate of the sealing material with the quantity of an external electric signal and accordingly adjusts the contact face pressure to enable controlling the amount of leakage of the fluid highly precisely, so that it can be used for all applications, and to provide a valve structure using the shaft sealing device.

To attain the above object, the invention relates to a shaft sealing device comprising a device body, a shaft sealing portion disposed in the device body, a shaft sealing body formed of a macromolecular material and made expansible or contractible, or deformable, through external electro stimuli applied to the shaft sealing body and flow passages disposed in the shaft sealing portion for feeding a fluid leaked due to expansion or contraction, or deformation, of the shaft sealing body.

The invention also relates to the above shaft sealing device, wherein the shaft sealing body is formed of an electro stimuli-responsive macromolecular material that is subjected to enlarged deformation in a direction orthogonal to a voltage application direction when having been charged with external electro stimuli, thereby heightening shaft sealing power whereas the electro stimuli-responsive macromolecular material is returned to an original position while being subjected to contracted deformation in the direction orthogonal to the voltage application direction when having been discharged, thereby inducing an appropriate leakage phenomenon due to a decrease in shaft sealing power, or that is returned to the original position while being subjected to the enlarged deformation in the direction orthogonal to the voltage application direction when having been discharged, thereby heightening the shaft sealing power whereas the electro stimuli-responsive macromolecular material is lowered in shaft sealing power while being subjected to contracted deformation in the direction orthogonal to the voltage application direction when having been charged with the external electro stimuli, thereby inducing the appropriate leakage phenomenon.

The invention also relates to the first mentioned shaft sealing device, wherein the shaft sealing body is formed of an electroconductive macromolecular material that is returned to original position while being expanded when application of external electro stimuli has been stopped, thereby heightening shaft sealing power, whereas the electroconductive macromolecular material is lowered in shaft sealing power while being shrunk when the external electro stimuli have been applied, or that is heightened in shaft sealing power while being expanded when the external electro stimuli have been applied, whereas the electroconductive macromolecular material is returned to the original position while being shrunk when the application of the external electro stimuli have been stopped, thereby inducing an appropriate leakage phenomenon due to a decrease in shaft sealing power.

The invention relates to the first mentioned shaft sealing device, wherein the shaft sealing body is formed of an ionically conductive macromolecular material that is returned to an original position while being deformed when application of external electro stimuli has been stopped, thereby heightening shaft sealing power, whereas the ionically conductive macromolecular material is deformed when the external electro stimuli have been applied, thereby inducing an appropriate leakage phenomenon due to a decrease in shaft sealing power, or that is heightened in shaft sealing power while being deformed when the external electro stimuli have been applied, whereas the ionically conductive macromolecular material is returned to the original position while being deformed when the application of the external electro stimuli has been stopped, thereby inducing the appropriate leakage phenomenon due to a decrease in shaft sealing power.

The invention relates to the first mentioned shaft sealing device, wherein the shaft sealing body is formed of an electro stimuli-responsive macromolecular material that is returned to an original position while being deformed when application of external electro stimuli has been stopped, thereby heightening shaft sealing power, whereas the electro stimuli-responsive macromolecular material has deformed a section thereof other than a section thereof to which the external electro stimuli have been applied, thereby inducing an appropriate leakage phenomenon due to a decrease in shaft sealing power.

The invention relates to the first mentioned shaft sealing device, wherein the shaft sealing body is formed of an electro stimuli-responsive macromolecular material that deforms, when external electro stimuli have been applied, a section thereof other than a section thereof to which the external electro stimuli have been applied, thereby heightening shaft sealing power, whereas the electro stimuli-responsive macromolecular material is returned to an original position while being deformed when application of the external electro stimuli has been stopped, thereby inducing an appropriate leakage phenomenon due to a decrease in shaft sealing power.

The invention relates to any one of the first to fourth mentioned shaft sealing devices, further comprising a holder capable of retaining the shaft sealing body on a retaining surface thereof from upper and lower directions and electrodes which are provided on the retaining surface of the holder and which are electrically connected to an exterior of the device body.

The invention relates to any one of the first, fifth and sixth mentioned shaft sealing devices, wherein the shaft sealing body is provided with electrodes which are connected to an exterior of the device body in a state clamping part of upper and lower surfaces of the shaft sealing body.

The invention relates to any one of the first to sixth mentioned shaft sealing devices, wherein the shaft sealing body comprises at least two shaft sealing bodies disposed in the device body and the flow passages comprise at least three leaked-fluid flow passages disposed in the device body, and further comprising a holder capable of retaining the shaft sealing bodies, respectively, on a retaining surface thereof from upper and lower directions and electrodes which are provided on the retaining surface of the holder and which are electrically connected to an exterior of the device body, wherein application and stop of application of external electro stimuli to the shaft sealing bodies from the electrodes makes the shaft sealing bodies expansible or contractible, or deformable, to make the flow passages switchable.

The invention relates to any one of the second to ninth mentioned shaft sealing devices, wherein the leakage phenomenon includes a minute leakage phenomenon.

The invention relates to a shaft sealing device comprising a device body, a holder, and an annular shaft sealing body which is inserted into the device body via the holder, which has a base fixed to the holder or device body and a distal free end serving as a shaft sealing portion and which allows the shaft sealing portion to expand or contract in a substantially perfectly circular shape when external electro stimuli have been applied thereto, thereby obtaining a shaft sealed state or a fluid leaking state.

The invention relates to the above shaft sealing device, wherein the shaft sealing body comprises a plate-like annular base material which is formed of a macromolecular material made expansible or contractible, or deformable, through external electro stimuli applied to the shaft sealing body and which has front and back surfaces provided respectively with electrodes.

The invention relates to the eleventh mentioned shaft sealing device, wherein the shaft sealing body comprises a hollow cylinder which is formed of a macromolecular material made expansible or contractible, or deformable, through external electro stimuli applied to the shaft sealing body and which has inner and outer circumferential surfaces provided integrally with electrodes, respectively.

The invention relates to a valve structure using any one of the eleventh to thirteenth mentioned shaft sealing device, wherein the device body is formed with plural flow passages communicating with an exterior of the device body, and the shaft sealing portion that is the free end of the shaft sealing body is disposed between adjacent flow passages so as to be brought to a shaft sealed state or a fluid leaking state, thereby making the flow passages switchable.

The invention relates to the above valve structure, wherein the shaft sealing body has a base near a substantially central part thereof and opposite free ends serving as shaft sealing portions that permit contact with or separation from at least two inner cylindrical annular portions, thereby making the flow passages switchable.

The invention relates to the fourteenth mentioned valve structure, wherein the shaft sealing body comprises at least two shaft bodies which are disposed in the device body and each of which has a free end serving as a shaft sealing portion brought to a shaft sealed state or a fluid leaking state.

EFFECTS OF THE INVENTION

According to the invention, it is possible to provide a shaft sealing device with a simple internal structure that switches a sealing state and an unsealing state of a fluid, with high sealing performance maintained, because of no abrasion accompanying the movement of a shaft sealing body, thereby enabling feeding a fluid at a predetermined flow rate, and adjusts the amount of expansion or contraction, or the amount of deformation, of the shaft sealing body with the quantity of an external electric signal and accordingly adjusts the contact face pressure to enable controlling the amount of leakage of the fluid highly precisely, so that it can be used for all applications. In addition, since the shaft sealing body can be deformed in the absence of a moving mechanism to enable preventing the inside of the shaft sealing device from being deteriorated, the shaft sealing device can fulfill an excellent shaft sealing function over a long period of time. As a result, the shaft sealing device of the present invention can be utilized as a substitute for an electromagnetic valve and, further since the amount of minute leakage in a shaft sealed state can be controlled, utilized in various technical fields.

According to the invention, since only the shaft sealing body can be increased or decreased in diameter through performing or stopping the application of the external electro stimuli, it is possible to switch between the sealed state and the unsealed state while preventing deterioration of the device body through keeping the movable portion of the device body to the minimum. In the sealed state, the shaft sealing device can heighten the shaft sealing power to fulfill the excellent sealability and, in the unsealed state, can flow a fluid at a constant flow rate, with the amount of leakage peculiar to the device body as the flow rate. In this case, furthermore, the shaft sealing device allows the shaft sealing body to have an EPAM structure that can enlarge the pressure or distortion amount during the operation to enable a higher shaft sealing function to be fulfilled, allows the device body to have a light weight because of the simple structure and allows the sound generated to be quiet.

According to the invention, it is possible to provide the shaft sealing device, in which various macromolecular materials are used to enable the configuration of the shaft sealing body and the provision of the shaft sealing structure made appropriate in accordance with the macromolecular materials different in expansion or contraction, or deformation, of the shaft sealing portion. Also in this case, excellent functionality in the time of sealing or unsealing can be fulfilled similarly in the case of the provision of the EPAM structure. Of these inventions, according to the inventions of claims5and6in particular, it is possible to provide the shaft sealing device, in which since the section other than the section to which the external electro stimuli have been applied is deformed, it is unnecessary provide the section with electrodes and, since the deformed portion is the free end, it is possible to make the deformation amount large. For these reasons, it is possible to provide the shaft sealing device capable of acquiring a large amount of leakage flow rate and controlling the flow rate with high precision.

According to the invention, since it becomes possible to control the voltage applied from the exterior of the device body to the shaft sealing body, it is possible to provide the shaft sealing device capable of applying the device body to a small-sized device or instrument and downsizing a space occupied by the shaft sealing device and thus being utilized at various places.

According to the invention, it is possible to provide the shaft sealing device that can be used as a flow passage switching valve and applied to various switching mechanisms including a piston-cylinder mechanism, for example and, also in this case, control the piston-cylinder operation speed with high precision.

According to the invention, since minute leakage in the shaft sealed state can be controlled, it is possible to provide the shaft sealing device capable of making a control of a minuter leakage amount in addition to a control of a leakage amount of an ordinary fluid flowing.

According to the invention, the shaft sealing device has a shaft sealing structure capable of expanding or contracting the free end of the shaft sealing body in a perfectly circular shape relative to the inner circumferential surface of the device body while maintaining high precision and controlling the shaft sealing body in the shaft sealed state or fluid leakage state on the primary and secondary sides through the circumferential surface of the shaft sealing body coming into contact with or separating from the cylindrical flow passage and can therefore be applied to various kinds of flow passages.

According to the invention, since only the shaft sealing body can be expanded or contracted through performing or stopping the application of the external electro stimuli, it is possible to switch between the sealed state and the unsealed state while preventing deterioration of the device body through keeping the movable portion of the device body to the minimum. In the sealed state, the shaft sealing device can heighten the shaft sealing power to fulfill the excellent sealability and, in the unsealed state, can flow a fluid at a constant flow rate, with the amount of leakage peculiar to the device body as the flow rate.

According to the invention, it is possible to provide the shaft sealing device having the effects, in addition of the effects of claim12, of reducing the distortion of the shaft sealing body after the integral formation of the shaft sealing body in the shape of a ring and making the control of the shaft sealed state or fluid leaking state with higher precision.

According to the invention, it is possible to provide the valve structure using the valve sealing device capable of making the structure of the shaft sealing simple and compact and being utilized as a switching valve of a structure which can switch plural flow passages and which has not existed conventionally. In addition, since the number of the flow passages can be increased in accordance with embodiments and, even in the case of adopting the multiway valve structure, each flow passage can be brought to the prescribed shaft sealed state or fluid leakage state while controlling the shaft sealed state or fluid leakage state with high precision, the valve structure having the shaft sealing device can be controlled as the multiway valve and utilized in various fields.

DETAILED DESCRIPTION OF THE INVENTION

The shaft sealing device of the present invention will be described hereinafter in detail with reference to the drawings. The shaft sealing device comprises a device body, a shaft sealing portion disposed in the device body, a shaft sealing body disposed in the shaft sealing portion, made of a macromolecular material and made expansible or contractible, or deformable, through outer electro stimuli, and flow passages which are formed in the shaft sealing portion and on which a fluid leaked due to the expansion or contraction, or the deformation, of the shaft sealing body. The expansion or contraction used herein in the present invention is defined by a change in shape of the shaft sealing body accompanying a change in volume of the shaft sealing body, and the deformation is defined by a change in shape of the shaft sealing body accompanying no change in volume of the shaft sealing body.

The macromolecular material used in the present invention includes at least four kinds of materials, one being an electro stimuli-responsive macromolecular material (dielectric elastomer), another an electroconductive macromolecular material, another an ionically conductive macromolecular material and the remainder an electro stimuli-responsive macromolecular material having deformed a section other than a section to which external electro stimuli have been applied. Here, the characteristics of each macromolecular material are shown inFIGS. 14 and 15.

When external electro stimuli have been applied to the shaft sealing body using the electro stimuli-responsive macromolecular material, the shaft sealing body is expansion-deformed in the direction orthogonal to the direction of the application to heighten shaft sealing power, whereas the shaft sealing body is returned to the original position while being contraction-deformed in the direction orthogonal to the application direction when the application of the external electro stimuli has been stopped, thereby lowering the shaft sealing power to induce an appropriate fluid leakage phenomenon. Thus, the shaft sealing device using the external electro stimuli forms flow passages when applying no current, i.e. makes a so-called normally open (NO) device operation, and has the material body deformed as a mode of change made when flowing a leaked fluid. In this case, a potential difference is given (voltage is applied) to between compliant electrodes provided respectively on the front and back surfaces of the elastomer material to reduce the material in the width direction by means of the Coulomb effect, thereby making a motion of expanding the material in the surface direction.

The shaft sealing body using the electroconductive macromolecular material is returned to the original position while being expanded when the application of the exterior electro stimuli has been stopped, thereby heightening the shaft sealing power, whereas it is contracted to lower the shaft sealing power when the external electro stimuli have been applied thereto, thereby inducing an appropriate fluid leakage phenomenon. Thus, the shaft sealing device using the electroconductive macromolecular material is brought to a shaft sealed state, i.e. a so-called normally closed (NC) device state, when applying no current, and has the material body expanded or contracted as a mode of change made when a leaked fluid flows. In this case, a potential difference is given to the electroconductive macromolecular material, the material body is expanded or contracted through adsorption or desorption of moisture in the air.

The shaft sealing body using the ionically conductive macromolecular material is returned to the original position while being deformed when the application of the exterior electro stimuli has been stopped, thereby heightening the shaft sealing power, whereas it is deformed to lower the shaft sealing power when the external electro stimuli have been applied thereto, thereby inducing an appropriate fluid leakage phenomenon. Thus, the shaft sealing device using the ionically conductive macromolecular material is brought to the NC device state and has the material body expanded or contracted as a mode of change made when a leaked fluid flows. In this case, a potential difference is given to the ionically conductive macromolecular material, cations in the material body accompany moisture and move to the side of anions and, as a result, the material body has a lopsided water content to bend the material body.

The shaft sealing body using the electro stimuli-responsive macromolecular material having deformed a section other than a section to which external electro stimuli have been applied, is returned to the original position while being deformed when the application of the external electro stimuli has been stopped, thereby heightening the shaft sealing power, whereas the section other than the section to which external electro stimuli have been applied is deformed to lower the shaft sealing power, thereby inducing an appropriate fluid leakage phenomenon. Thus, the shaft sealing device using this electro stimuli-responsive macromolecular material is brought to the NC device state and the material body is deformed as a mode of change made when a leaked fluid flows.

As one example of the electro stimuli-responsive macromolecular material, for example, polyether urethane can be cited. This material comprises a mixture of a base compound and a curing agent. The base compound includes at least styrene, a nitrile compound, BHT (butylhydroxytoluene) and ester phthalate. On the other hand, the curing agent includes at least phthalic acid, diphenylmethane di-isothianate and ester phthalate. As a concrete example of the electro stimuli-responsive macromolecular material containing these components, a gel sheet manufactured by EXSEAL Corporation and sold under the trade name Hitohada (registered trademark) can be raised, for example. In addition, the electro stimuli-responsive macromolecular material may be formed of thin silicon film, for example, besides the polyether urethane and, in this case, the same functions and characteristics as described above can be fulfilled. Furthermore, other material than those mentioned above may be used insofar as the material can fulfill the same functions and characteristics as described above.

The electro stimuli-responsive macromolecular material is deformed as shown inFIG. 16. This figure shows a state in which an electric field is given (voltage is applied) to a shaft sealing body250formed of an electro stimuli-responsive macromolecular material that is polyurethane elastomer via fixed electrodes251and252each opposite locally to the shaft sealing body250. In the figure, when an electric field is applied to the fixed electrodes251and252, with the shaft sealing body250sandwiched between the fixed electrodes251and252, (1) dielectric polyols or polyols having dipole moment are oriented by the electric field to change the structure of a macromolecular chain at the opposite portions of the fixed electrodes251and252as shown inFIG. 16(a). At this time, as shown inFIG. 16(b), (2) the dielectric elastomer is reduced in the width direction by means of the Coulomb effect of the electric field by the opposite fixed electrodes251and252, thereby expanding the shaft sealing body250in the plane direction. In addition, (3) injection and uneven distribution of electric charge induce an asymmetric volume change at the electrodes.

Furthermore, in the peripheries of the circumferences of the fixed electrodes251and252, the electric field is equally attenuation-distributed in the radial direction (plane direction), with a value at the peripheries of the fixed electrodes251and252as the maximum value, thereby operating a synthetic deforming stress by the three functions (1) to (3) to form stress distribution reducing the electric field homogenously in the plane direction, with the value at the peripheries of the fixed electrodes251and252as the maximum value. As a result, bend formation is induced.

Incidentally, any of the macromolecular materials may be molded in a material shape so as to have characteristics such that the movements made when performing or stopping the application of external electro stimuli are reversed. In addition, even in the case of using any macromolecular material, a fluid leak phenomenon includes so-called minute leakage that indicates a state in which leakage has induced in a shaft sealed state and, when applying external electro stimuli, the value of an electric signal is changed to control the amount of expansion or contraction, or the amount of deformation, thereby enabling an optional control of the degree of contact pressure of the shaft sealing body.

Each of the shaft sealing bodies using the electro stimuli-responsive macromolecular material, electroconductive macromolecular material and ionically conductive macromolecular material, of the macromolecular materials described above, is retained by a holder capable of retaining it in the upper and lower directions and, by providing the retaining surfaces of the holder for the shaft sealing body with electrodes electrically connected to an exterior of the device body, it becomes possible to apply or stop the application of the external electro stimuli from the electrodes to the shaft sealing body.

FIGS. 17 to 19are schematic views of the shaft sealing devices in which the shaft sealing bodies formed respectively of the electro stimuli-responsive macromolecular material, electroconductive macromolecular material and ionically conductive macromolecular material are retained by these holders. The shaft sealing device inFIG. 17has a shaft sealing body20A formed of the electro stimuli-responsive macromolecular material and formed in the shape of a disc accompanying a concentric through-hole21A and having an appropriate thickness. The shaft sealing body20A is provided on the upper and lower surfaces thereof with electrodes22A and23A, respectively. The shaft sealing body20A is retained from the upper and lower sides by holders40A and45A that are provided on the surfaces thereof for retaining the shaft sealing body20A with electrodes50A and51A, respectively, and is configured to enable applying voltage from the electrodes50A and51A thereto via the electrodes22A and23A.

When a power source for the shaft sealing device, not shown, has been turned on to give a potential difference to between the electrodes of the holders40A and45A, the shaft sealing body20A retained between the holders40A and45A is deformed to expand in the diametrical direction as shown inFIGS. 14 and 17(a), whereas when the electrodes have been deprived of the potential difference (the power source has been turned off), the shaft sealing body is deformed to contract its diameter in the diametrical direction as shown inFIG. 17(b).

The shaft sealing device inFIG. 18has a shaft sealing body20B formed of the electroconductive macromolecular material and formed in the shape of a disc accompanying a concentric through-hole21B and having an appropriate thickness. In addition, in the case where the shaft sealing body is formed of the electroconductive macromolecular material, since the material has a property of passing a current through itself, it is unnecessary to provide the upper and lower surfaces of the shaft sealing body with electrodes. The shaft sealing body20B is retained from the upper and lower sides by holders40B and45B that are provided on the surfaces thereof for retaining the shaft sealing body20B with electrodes50B and51B, respectively, and voltage is applied from the electrodes50B and51B to the shaft sealing body20B.

When a potential difference is given to between the electrodes of the holders40B and45B, the shaft sealing body20B retained between the holders40B and45B is contracted in the diametrical direction as shown inFIGS. 14 and 18(a), whereas when the electrodes have been deprived of the potential difference, the shaft sealing body20B is returned to the original position while being expanded in the diametrical direction.

The shaft sealing device inFIG. 19has a shaft sealing body20C formed of the ionically conductive macromolecular material and formed in the shape of a disc accompanying a concentric through-hole21C and having an appropriate thickness. The upper and lower surfaces of the shaft sealing body20C are provided with electrodes22C and23C, respectively. The shaft sealing body20C is retained from the upper and lower sides by holders40C and45C that are provided on the surfaces thereof for retaining the shaft sealing body20C with electrodes50C and51C, respectively, and voltage is applied from the electrodes50C and51C to the shaft sealing body20C.

When a potential difference is given to between the electrodes of the holders40C and45C, the shaft sealing body20C retained between the holders40C and45C is expanded on the lower surface side and contracted on the upper surface side as shown inFIGS. 14 and 19(a) and, as a result, entirely deformed to bend, thereby being reduced in shape in the contracting direction. When the electrodes have been deprived of the potential difference, the shaft sealing body20C is returned to the original position while being deformed in the diametrical direction.

In the meantime,FIG. 20is a schematic view of the shaft sealing device, in which retained is a shaft sealing body20D using an electro stimuli-responsive macromolecular material deforming a section other than a section to which external electro stimuli have been applied. In the shaft sealing device, the shaft sealing body20D is formed in the shape of a disc accompanying a concentric through-hole21D and having an appropriate thickness. The shaft sealing body20D is provided with electrodes22D and23D sandwiching part of the upper and lower surfaces of the shaft sealing body20D. The electrodes22D and23D are electrically connected to an exterior of the device body, and it is possible to perform or stop the application of the external electro stimuli to part of the shaft sealing body20D. In addition, the shaft sealing body20D is retained by holders40D and45D from the upper and lower directions via the electrodes22D and23D.

When a potential difference has been given to between the electrode22D on the side of the holder40D and the electrode23D on the side of the holder45D, with the electrode22D as a positive electrode and the electrode23D as a negative electrode, the shaft sealing body20D on the side of the electrode22D is bend-deformed toward the side of the electrode23D to deform part of the shaft sealing body20D having emerged as curved, thereby allowing the neighborhood of the outer periphery of the shaft sealing body20D to assume a shape contracted in the diametrical direction. In addition, elimination of the potential difference causes the shaft sealing body20D to be returned to the original position while being deformed in the diametrical direction.

Incidentally, even when using any of the macromolecular materials, by varying the shape of the shaft sealing body material to be molded, it is possible to change the movements (NO and NC movements) made when performing and stopping the application of the external electro stimuli to a movement reverse to the movement shown in the above figure. Also in this case, the same functions and effects as described above can be obtained. This is applicable to examples to be described later.

Furthermore, in addition to the expansion or contraction, or the deformation, of the shaft sealing body having the holders retained thereon, it is possible to expand or contract, or deform, the shaft sealing body having holders and a separator attached thereto. A shaft sealing device provided with a shaft sealing body having a separator attached thereto will be described.

FIGS. 21 and 22are schematic views in which a shaft sealing body has holders and a separator attached thereto. The shaft sealing device inFIG. 21has a shaft sealing body formed of an electro stimuli-responsive macromolecular material. The shaft sealing body30A is formed in the shape of a disc accompanying a concentric through-hole31A and having an appropriate thickness. The shaft sealing body30A is provided on the upper and lower surfaces thereof with electrodes32A and33A, respectively. The shaft sealing body30A and a separator35A are retained by holders40A and45A from the upper and lower sides thereof, and the retaining surfaces of the holders are provided with electrodes50A and51A, respectively. The separator35A is formed of a flexible electroconductive material and brings the electrodes32A and50A to a conduction state. The separator35A has a compliant concentric through-hole36A and fixed to the upper surface of the shaft sealing body30A by means of adhesive etc.

In the shaft sealing device, a potential difference has been given to between the electrodes of the holders40A and45A, the shaft sealing body30A retained between the holders40A and45A is urged to expand in the diametrical direction as shown inFIGS. 14 and 21(a) but, at this time, the compliant separator35A provided on the upper side prevents the shaft sealing body30A from being expanded on the upper side and, as a result, the shaft sealing body30A is deformed as being curved upward as the separator35A as the basis. In addition, the elimination of the potential difference allows the shaft sealing body to be deformed as returned to the original position as shown inFIG. 21(b).

The shaft sealing device inFIG. 22has a shaft sealing body formed of an electroconductive macromolecular material and, similarly to the case of the shaft sealing body formed of the electro stimuli-responsive material, the shaft sealing body30B is formed in the shape of a disc accompanying a concentric through-hole31B and having an appropriate thickness. A separator35B is fixed to the upper surface of the shaft sealing body30B by means of adhesion etc. Holders40B and45B retains the shaft sealing body30B and separator35B in the upper and lower directions and has the retaining surfaces thereof provided with electrodes50B and51B.

In the shaft sealing device, a potential difference has been given to between the electrodes of the holders40B and45B, the shaft sealing body30B retained between the holders40B and45B is urged to contract in the backward direction as shown inFIGS. 14 and 22(a) but, at this time, the compliant separator35A provided on the upper side prevents the shaft sealing body30B from being contracted on the upper side and, as a result, the shaft sealing body30B is deformed as being curved downward as the separator35B as the basis. In addition, the elimination of the potential difference allows the shaft sealing body to be returned to the original position while being expanded.

Incidentally, since the ionically conductive macromolecular material to which a potential difference is given in a state having holders40C and45C only attached thereto is deformed as being curved, though attachment of a separator is not required, a separator may be attached as occasion demands. In this case, the shaft sealing body is reinforced with the separator and can function similarly to that provided with no separator.

Furthermore, since it is sufficient that the electro stimuli-responsive macromolecular material, which has deformed a section thereof other than a section to which external electro stimuli have been applied, is brought to a state having part of the upper and lower surfaces thereof sandwiched between the electrodes, though attachment of a separator is not required similarly to the case of the ionically conductive macromolecular material, a separator may be attached as occasion demands. As described in the foregoing, the shaft sealing device of the present invention may be configured to have different internal structures using various kinds of macromolecular materials and, thus, an appropriate configuration can be adopted in accordance with the state of implementation.

Next, the switching action of the shaft sealing device according to the present invention will be described in more detail using a typical example selected from the above examples.FIGS. 1 to 3show one example of the shaft sealing device according to the present invention. The shaft sealing device in this example has a shaft sealing body formed of an electro stimuli-responsive macromolecular material and has a structure in which the shaft sealing body is retained by a holder only. A device body10comprises a housing11, a shaft portion15disposed in the housing, a shaft sealing body20disposed in the shaft sealing portion, and leakage flow passages13and14formed in the shaft sealing portion15for enabling fluid leakage by deformation of the shaft sealing body20.

The housing11is formed in a substantially tubular shape, and the flow passages within the housing11are shaft-sealed with the shaft sealing portion15. The shaft sealing portion15is provided with a seating face16, and the leakage flow passages13and14are disposed on the opposite sides of the seating face16and extend in parallel to each other in the circumferential direction. After the shaft sealing body20is disposed within the shaft sealing portion15, an abutting surface24of the shaft sealing body20is abutted on the seating face16when the shaft sealing body20has been deformed, thereby enabling the formation of a shaft seal. In addition, when the leakage passages13and14have communicated with each other, a fluid can be leaked. Incidentally, though not shown, a flow passage can be configured through connection of an appropriate a pipe line, such as a joint or a pipe, to the leakage flow passages13and14.

The shaft sealing body20accompanies flexible upper and lower electrodes22and23and is configured to enable the value of an electric signal to be changed when voltage is applied to the electrodes22and23. In addition, the shaft sealing body20is configured to enable the amount of deformation to be controlled by the change of the electric signal value and the degree of pressure contact with the seating face16to be optionally changed. The shaft sealing body20assumes a substantially circular outer shape and is provided at the center section with a through-hole21. It goes without saying that the outer shape of the shaft sealing body20includes various shapes, such as quadrangles including a rectangle and a trapezoid, and polygons, besides the annular shape shown in the drawing. The shaft sealing body20is provided on the outer periphery thereof with the abutting surface24that can abut on the seating face16of the housing11and, at this time, it is possible to establish a shaft sealed state, a minute fluid leakage state in which contact surface pressure is adjustable and a fluid leakage state when the abutting surface and the seating face have separated from each other to release the shaft sealed state.

InFIGS. 4 and 5, a holder40comprises an upper holder41and a lower holder45that sandwich the shaft sealing body20. The upper holder41has a substantially tubular portion41aand a flange portion41bdisposed on the lower surface of the tubular portion41a. The upper holder41is provided with an external electrode50extending along the axial direction from a retaining surface41con the lower surface of the flange portion41bfor retaining the shaft sealing body20to part of the inner peripheral surface of the tubular portion41a. The external electrode50is connected to the exterior of the device body10. When voltage is applied to the external electrode50, it can be applied to the upper electrode22of the shaft sealing body20. Thus, the external electrode50is patterned on the front surface of the upper holder41that is a three-dimensional circuit-molded part.

The lower holder45has a substantially columnar portion45aand a flange portion45bdisposed on the lower surface of the columnar portion45a. The lower holder45is provided with an external electrode51extending along the axial direction from a retaining surface45cfor retaining the shaft sealing body20to part of the outer peripheral surface of the columnar portion45a. The external electrode51is connected to the exterior of the device body10. When voltage is applied to the external electrode51, it can be applied to the lower electrode23of the shaft sealing body20. Thus, similarly to the external electrode50, the external electrode51is patterned on the front surface of the lower holder45with a three-dimensional circuit.

The outside diameter of the flange portions41band45bof the upper and lower holders41and45is made substantially equal to the outside diameter of the shaft sealing body20. In addition, the outside diameter of the columnar portion45aof the lower holder45is made smaller than the inside diameter of the inner peripheral surface of the tubular portion41aof the upper holder41and the inside diameter of the through-hole21of the shaft sealing body20to enable the columnar portion45ato be inserted into the inner peripheral part of the tubular portion41a.

By inserting a columnar portion45dof the lower holder45into the through-hole21and the columnar portion45aof the lower holder45into the tubular portion41aof the upper holder41, the shaft sealing body20is sandwiched between the flange portions41band45b. As a result, the components can be made integral in a state in which the external electrodes50and51on the sides of the flange portions41band45bhave come into contact with the upper and lower electrodes22and23of the shaft sealing body20, respectively. At this time, since the axially extending external electrodes50and51are disposed at circumferential positions opposed to each other, they are not brought into contact with each other do not induce any short circuit. In addition, in the presence of a bump gap, the electrode51does not short-circuit the external electrode50patterned on the upper holder flange portion lower side41c. When voltage has been applied to the external electrodes50and51and given to the shaft sealing body20, the shaft sealing body20is configured such that it is deformed in the circumferential direction to enable diameter enlargement.

The holders41and45can retain the shaft sealing body20while locally coming into pressure contact with it from the upper and lower directions and, in the presence of the pressure contact portions, it is possible to prevent a fluid from passing through the shaft sealing body and leaking and to perform electrical conduction. In addition, the portions other than the pressure contact portions have suitable gaps so as to enable the shaft sealing body20to be expanded or contracted freely. Furthermore, as shown inFIG. 2, the upper side of the inner peripheral surface of the tubular part41aof the upper holder41and the upper side of the outer peripheral surface of the columnar part45aof the lower holder45are provided respectively with grooves54and55to which wires not shown are connected. Thus, voltage can be applied from the exterior of the device body10to the electrodes50and51via the wires.

With the above configuration, the shaft sealing body20is used to enable provision of a structure of an EPAM that is an artificial muscle, and the entire structure has excellent characteristics such that a force generated at the time of the deformation of the shaft sealing body20can be enlarged and that the entire structure has a light weight, makes a drive structure simple and compact, allows the sound generated during the operation to be quiet and can be driven at a low voltage.

The shaft sealing body20attached to the holders41and45is attached to a attachment body17formed in a substantially tubular shape, and the attachment body17is attached to the inside of the housing11. As a result, the shaft sealing body20can be disposed at an appropriate position within the device body10. An O-ring18is provided between the attachment body17and the housing11for preventing occurrence of leakage from between them. In addition, the same effect can be obtained through integral provision of the attachment body17and the holder41.

A power supply circuit60is connected to each of the external electrodes50and51so that voltage may be applied to the external electrodes50and51and provided therein with a variable source61, a switch62and a variable resistor63and, when the switch62is turned on to close the circuit, voltages of different polarities are applied to the electrodes22and23of the shaft sealing body20to perform electric charge. When voltage of negative polarity has been applied to the external electrode50of the upper holder41, for example, voltage of positive polarity is to be applied to the external electrode51of the lower holder45. In addition, these voltages can be controlled with the variable source61or variable resistor63.

Subsequently, the operation of the above embodiment of the shaft sealing device according to the present invention will be described. When the switch62has been turned on as shown inFIG. 3from the state ofFIG. 1, voltages of different polarities are applied to the external electrode50of the upper holder41and the external electrode51of the lower holder45, respectively, and to the upper and lower electrodes22and23of the shaft sealing body20, respectively. As a result, the shaft sealing body20is deformed as being expanded in the circumferential direction and, by this deformation, the abutting surface24of the shaft sealing body20is brought into pressure contact with the seating face16of the device body10to shaft-seal the flow passage between the leakage flow passages13and14, thereby enabling the fluid to be sealed.

At this time, since adjustment of the variable source61or variable resistor63controls the amount of voltage (degree of voltage) to be applied or the applying time of the voltage (transient response) to enable the amount of deformation or deformation response time of the shaft sealing body20to be adjusted, the abutment surface24can be brought into contact with the seating face16with appropriate suppress strength, thereby enabling leakage to be effectively prevented and the shaft sealing effect to be heightened. In addition, by increasing the voltage gradually from the fluid leaked state to deform the shaft sealing body, it is possible to optionally control the state from a minute level of leaked state to a sealed state. Furthermore, by decreasing the voltage to be applied from the shaft sealed state little by little, it is possible to control so-called minute leakage that induces leakage, with the shaft sealed state maintained. Moreover, by continuously decreasing the voltage to be applied, it is possible to adjust by the shaft sealing body20the amount of a gap δ to be described later and, as a result, adjust the flow rate to a prescribed value. Thus, the device body10can control a minute level of fluid leakage amount in addition to the induction of fluid leakage or the control of the amount of leakage to zero.

On the other hand, when the switch62has been turned off as shown inFIG. 1from the state ofFIG. 3, an external discharge circuit, though not shown, discharges an electric charge from the upper and lower electrodes22and23of the shaft sealing body20via the external electrodes50and51. As a result, the shaft sealing body20is brought to a nonconductive state and deformed as being reduced in diameter in the circumferential direction to form the concentric gap δ between the shaft sealing body20(abutting surface24) and the housing11(seating face16). The fluid kept still sealed is flowed as leaking from the gap δ to enable communication between the flow passages13and14. In the case, since the amount of the gap δ at the time of turning the switch62off is peculiar to the device body10, the amount of the fluid leaked peculiar to the device body can be produced and utilized as a constant fluid flow rate. As a result, the shaft sealing device can be applied to an electromagnetic valve, for example.

Thus, the device body10deforms the shaft sealing body20as being enlarged or reduced in diameter through application of external electro stimuli via the external electrodes50and51. Therefore, the shaft sealing body20can seal the fluid in the shaft sealed state in which it is not moved, or flow the fluid while adjusting the amount of leakage after releasing the shaft sealed state. In addition, when an internal structure in which the shaft sealing body20constitutes a movable portion has been adopted, since there is no need to provide a moving mechanism, such as a screw feeding mechanism, sealing and unsealing of the fluid can easily be performed through a reversible switching operation. Furthermore, since the shaft sealing body20is not twisted at the moving time, it can be prevented from being injured or deteriorated and maintain an excellent shaft sealing function.

Incidentally, in this example, since the shaft sealing body is formed of an electro stimuli-responsive macromolecular material, it is deformed as being expanded or contracted when voltage has been applied thereto. However, when the shaft sealing body is formed of an electroconductive material, it is enlarged or reduced through the expansion or contraction thereof when voltage has been applied thereto. In addition, when the shaft sealing body is formed of an ionically conductive macromolecular material or an electro stimuli-responsive macromolecular material deforming a section other than a section to which external electro stimuli have been applied, it is deformed when voltage has been applied thereto. In addition, since either one of the leakage flow passages13and14may constitutes a primary or secondary flow passage, the fluid can be leaked or sealed in an optional direction.

Next, another example of the shaft sealing device according to the present invention will be described. Incidentally, in the following examples, the same portions as in the above example will be given the same reference numerals and the descriptions thereof will be omitted. In addition, also in this example, though the macromolecular material used as the shaft sealing body includes at least four kinds of macromolecular materials, i.e. one being an electro stimuli-responsive macromolecular material, another an electroconductive macromolecular material, another an ionically conductive macromolecular material and the remainder an electro stimuli-responsive macromolecular material deforming a section other than a section to which external electro stimuli have been applied, the case of using the electro stimuli-responsive macromolecular material will be described in this example for convenience of explanation.

In this example, as shown inFIGS. 6 to 8, at least two shaft sealing bodies80and85are provided within a device body70, a holder90capable of retaining the shaft sealing bodies80and85in the upper and lower directions, respectively, is provided, and retaining surfaces of the holder90for these shaft sealing bodies are provided with electrodes electrically connected to the exterior of the device body70. By performing or stopping application of external electro stimuli from the electrodes to deform the shaft sealing bodies80and85, at least three fluid flow passages73,74and75formed in a substantially tubular housing71for the device body70can be switched.

As shown inFIGS. 9 and 10, the holder90comprises a first holder91, a second holder92, a third holder93and a fourth holder94and, between adjacent ones of these holders91,92,93and94, the two shaft sealing bodies80and85and a separator95intervene, respectively. The first holder91has a substantially tubular portion91aand a flange portion91bon the lower side of the tubular portion91a. An electrode100is formed to extend along the axial direction from the lower side of the flange portion91bretaining the shaft sealing body80to part of the inner peripheral surface of the tubular portion91aand is connected to the exterior of the device body70. As a result, voltage applied from the upper side of the tubular portion91ato the electrode100can be applied to an upper surface82of the shaft sealing body80.

The second holder92has a substantially tubular portion92aand a flange portion92bon the lower side of the tubular portion92a, and an electrode101is formed to extend along the axial direction from the upper side of the flange portion92bto part of the outer peripheral surface of the tubular portion92aand is connected to the exterior of the device body70. As a result, when voltage has been applied from the electrode101, it can be applied to a lower surface83of the shaft sealing body80. The voltage has the opposite polarity to the voltage applied to the electrode100.

The third holder93has a substantially tubular portion93aand a flange portion93bon the lower side of the tubular portion93a, and an electrode102is formed to extend along the axial direction from the lower side of the flange portion93bto part of the inner peripheral surface of the tubular portion93aand is connected to the exterior of the device body70. Furthermore, the fourth holder94has a substantially columnar portion94aand a flange portion94bon the lower side of the columnar portion94a, and an electrode103is formed to extend along the axial direction from the upper side of the flange portion94bto part of the outer peripheral surface of the columnar portion94aand is connected to the exterior of the device body70. The voltage in the electrode103of the fourth holder is opposite to that in the electrode102of the third holder.

The electrodes100,101,102and103of the holders91,92,93and94can be detached to the exterior from the upper sides of the tubular portions91a,92aand93aand columnar portion94a, respectively, and voltage can be applied from an external power circuit to each of the electrodes. Incidentally, the power source is not shown in this example, but the lead line therefor is only shown.

The outside diameter of the flange portions91b,92b,93band94bis substantially equal to that of the shaft sealing bodies80and85and spacer95. The outside diameter of the spacer95may be made smaller appropriately. In addition, it is designed that the relations of the inside diameter of the tubular portion of the first holder91>the outside diameter of the tubular portion of the second holder92, the inside diameter of the tubular portion of the second holder92>the outside diameter of the tubular portion of the third holder93and the inside diameter of the tubular portion of the third holder93>the outside diameter of the columnar portion of the fourth holder94have been satisfied. The shaft sealing bodies80and85and the spacer95have through-holes so as to be attached to, respectively, between the first and second holders91and92, between the third and fourth holders93and94and between the second and third holders92and93.

When making these components integral with one another, the tubular portions and columnar portion are inserted into the corresponding tubular portions disposed upward, respectively, with the shaft sealing body80intervening between the first and second holders91and92, the shaft sealing body85between the third and fourth holders93and94and the spacer95between the second and third holders92and93. At this time, it is configured that the electrodes100and101of the first and second holders91and92do not come into contact with the electrodes102and103of the third and fourth holders93and94and, when voltages have been applied to these electrodes, the voltages of different polarities are applied to the upper and lower surfaces of the shaft sealing bodies80and85to enable the shaft sealing bodies80and85to be enlarged in diameter in the circumferential direction, respectively. The shaft sealing bodies80and85made integral are attached to an attachment body78forming a substantially tubular shape in conjunction with the holder90and spacer95, and the attachment body78is attached to the inside of the housing71via an O-ring79. In the meanwhile, the attachment body78and the holder91may be made integral with each other.

In the state shown inFIG. 6, when the application of voltage to the electrodes100and101has been stopped and when voltage has been applied to the electrodes102and103, the shaft sealing body85is deformed as being enlarged in diameter by the pressure to bring an abutting surface89of the shaft sealing body85into contact with a seating face77, thereby closing a flow passage between the leakage flow passages74and75. On the other hand, the shaft sealing body80between the leakage flow passages73and74is in non-conductive state to maintain a diameter-reduced state, thereby inducing a gap6′ between an abutting surface84and a seating face76and, therefore, the leakage flow passages73and74are allowed to communicate via the gap6′ with each other to form a leakage flow passage.

Stopping the application of voltage to the electrodes102and103from the state shown inFIG. 6and applying voltage to the electrodes100and101brings about a state shown inFIG. 8. In the figure, since the shaft sealing body85is in a non-conductive state to become in a deformed state as being reduced in diameter, a gap6″ is formed between the abutting surface89and the seating face77. On the other hand, the shaft sealing body80is in a conductive state to maintain a deformed state as being enlarged in diameter, thereby bringing the abutting surface84of the shaft sealing body80into pressure contact with the seating face76. As a result, the flow passage between the leakage flow passages73and74is closed, whereas the flow passage between the leakage flow passages74and75becomes in a state communicating with each other. In this example, as described above, by providing the plural shaft sealing bodies80and85and controlling the application of voltage to deform the shaft sealing bodies80and85and bring the abutting surfaces84and89into contact with or separate them from the seating faces76and77provided between the adjacent leakage flow passages73,74and75, the leakage flow passages can be switched. Also in this case, similarly to the aforementioned example, control of the voltage to be applied varies the size of the gap δ″ to enable the adjustment of the leakage flow rate and, furthermore, in the case of adjusting the voltage in the state of bringing the shaft sealing body into pressure contact with seating face, the amount of minute leakage can be controlled.

InFIG. 11, a holder110of a different shape is shown and configured to have a flange portion112provided on the outside diameter side thereof with plural bored holes113and, when having been accommodated within a shaft sealing portion116of a housing115, form a gap α between the shaft sealing portion116and the outer periphery of the flange portion112. Incidentally, in this example, the bored holes113are disposed in the circumferential direction of the flange portion112at positions on the outside diameter side thereof from the intermediate position thereof. The holder110can guide a shaft sealing body, not shown, when having been expanded or contracted, or deformed, to make the shape of the shaft sealing body stable and enable the flange portion112to serve as a guide when the shaft sealing body attached to the holder110is inserted into the housing115.

When the shaft sealing body not shown is attached to the holder110, the outside diameter of the shaft sealing body when having been contracted is set to be smaller than the positions of the bored holes113and, when the shaft sealing body attached to the holder110is contracted or deformed in the diameter-reducing direction, it is possible to secure (increase) the area for passage of a fluid, thereby making it possible to increase the amount of leakage (flow rate) at the time of shaft sealing leakage. On the other hand, when the shaft sealing body is expanded or deformed in the diameter-enlarging direction, it can stop up the bored holes113to close the flow passages, thereby making it possible to seal the fluid with exactitude. The flange portion may be formed with cancellous holes, for example, insofar as it can close the flow passages when the shaft sealing body has been increased in diameter or, when the shaft sealing body has been decreased in diameter, increase the area for the passage of the fluid. Thus, the mode of the holder does not matter. In addition, the above mode of the holder can be utilized for any of the aforementioned shaft sealing devices.

FIG. 12shows an example in which the shaft sealing body is applied to a safety valve120. In the figure, a device body121has a shaft sealing body122capable of being expanded or contracted, or deformed, by performing or stopping the application of voltage, and the shaft sealing body122is accommodated in a housing123. The housing123is attached to a pipe124so as to allow an internal flow passage thereof to communicate with the pipe. In addition, a pressure sensor125can transmit the fluctuation in internal pressure of the pipe124as a voltage signal and detect the variation in internal pressure of the pipe124. A switch circuit126is disposed between the pressure sensor125and the device body121and configured to enable stopping the application of voltage to the device body121in accordance with the fluctuation of the pressure detected with the pressure sensor125. Furthermore, to the switch circuit126, voltage having a reference value for provisionally sealing the shaft sealing body during the course of the shaft sealing body122reaching a prescribed pressure value in an initial seal of pressure into the pipe is applied.

The safety valve120stops the application of voltage with the switch circuit126when the value of the internal pressure of the pipe124detected with the pressure sensor125has exceeded a prescribed value and, by the voltage application stopping, the shaft sealing body122is contracted or deformed from the normally expanded or deformed state to form a gap between the housing123for the device body121and the shaft sealing body122, thereby enabling the internal pressure of the pipe124to be lowered through relief of the pressure from the gap. In addition, when the pressure has been returned to the prescribed value or less after the pressure relief, the switch circuit126is used to apply the voltage of the pressure sensor125to the shaft sealing body122to change the shaft sealing body122from the contracted or deformed state to the expanded or deformed state, thereby enabling sealing pressure leakage.

FIG. 13shows an example in which the shaft sealing device of the present invention is applied to a piston-cylinder drive mechanism130. In the figure, a device body131has four shaft sealing bodies132,133,134and135capable of being expanded or contracted, or deformed, in the circumferential direction accommodated in a housing136to enable air flow passages to be switched. The housing136is formed therein with leakage flow passages137,138,139,140and141. The leakage flow passage137is provided so as to enable compressed air to be supplied from the exterior to the device body131, and the leakage flow passages138and139are provided so as to enable the compressed air within the device body131to be discharged to the exterior. In addition, the leakage flow passages140and141are connected to a cylinder portion130aand provided so as to enable supply and discharge the compressed air between the device body131and the cylinder portion130a.

The shaft sealing bodies132,133,134and135are disposed between the leakage flow passages138and141, between the leakage flow passages141and137, between the leakage flow passages137and140and between the leakage flow passages140and139, respectively, and application of voltage to the shaft sealing bodies132,133,134and135is controlled to expand or contract, or deform, these shaft sealing bodies to enable a shaft seal between the adjacent leakage flow passages.

InFIG. 13(a), by making a control so that application of voltage to the shaft sealing bodies132and134is stopped to contract or deform these shaft sealing bodies in the diameter-reducing direction and so that voltage is applied to the shaft sealing bodies133and135to expand or deform these shaft sealing bodies in the diameter-enlarging direction, the flow passage between the leakage flow passages137and140and the flow passage between the leakage flow passages141and138are allowed to communicate with each other as shown and, at the same time, the flow passage between the leakage flow passages139and140and the flow passage between the leakage flow passages141and137are closed, respectively. When compressed air has been supplied from the leakage flow passage137, with the above state maintained, the compressed air was sent into the cylinder portion130avia the leakage flow passage140to move a piston130bleftward in the figure. This movement of the piston130bdischarges the compressed air within the cylinder portion130afrom the leakage flow passage138via the leakage flow passage141.

On the other hand, inFIG. 13(b), by making a control so that voltage is applied to the shaft sealing bodies132and134to expand or deform these shaft sealing bodies in the diameter-enlarging direction and so that application of voltage to the shaft sealing bodies133and135is stopped to contract or deform these shaft sealing bodies in the diameter-reducing direction, the flow passage between the leakage flow passages137and141and the flow passage between the leakage flow passages140and139are allowed to communicate with each other as shown and, at the same time, the flow passage between the leakage flow passages141and138and the flow passage between the leakage flow passages137and140are closed, respectively. When compressed air has been supplied from the leakage flow passage137, with the above state maintained, the compressed air was sent into the cylinder portion130avia the leakage flow passage141to move a piston130brightward in the figure. This movement of the piston130bdischarges the compressed air within the cylinder portion130afrom the leakage flow passage139via the leakage flow passage140. Thus, in the piston-cylinder drive mechanism130, it is possible to switch the flow passages through the control of the application of voltage to each of the shaft sealing bodies132,133,134and135and enable the piston130bto reciprocate through the supply of the compressed air from one of the leakage flow passages137.

Though the cases of providing the shaft sealing device of the present invention with the safety valve120and the piston-cylinder drive mechanism130have been described above, these are absolutely mere examples. The shaft sealing device of the present invention can shaft-seal the primary and secondary sides of a fluid flow passage and release the shaft seal to induce a prescribed leakage amount, and may be applied to various apparatus and mechanisms insofar as minute leakage can be controlled.

Though not shown, the shaft sealing device of the present invention may be configured have the shaft sealing portion formed like a room to constitute a shaft sealing chamber in which a fluid can be accommodated besides the configuration thereof as part of a flow passage. In addition, the device body may be formed of a material resistant to a drug solution or provided as an internal structure, thereby enabling supply of the drug solution while sealing the drug solution or controlling the flow rate of the drug solution. As a result, it is possible to provide the shaft sealing device as part of a liquid crystal fabricating plant or a semiconductor precision plant. In this case, the material for a pipe connected to an inlet or outlet side of the device can be selected freely and, in accordance with a fluid to be used, can be changed appropriately.

Next, a valve structure using the shaft sealing device will be described. In the shaft sealing device in this case, an annular shaft sealing body is inserted into a device body via a holder, the shaft sealing body has a base fixed to the holder or device body and an opposite free end and, when external electro stimuli have been applied to the shaft sealing body, the shaft sealing body is expanded or contracted in the shape of a substantially perfect circle, with the free end as a shaft sealing portion, thereby obtaining a shaft sealed state or a fluid leaked state.

In the valve structure using the shaft sealing device, the device body is formed therein with plural flow passages communicating with the exterior, and the shaft sealing portion that are the free end of the shaft sealing body is disposed between the flow passages to bring the shaft sealing portion to a shaft sealed state or liquid leaked state, thereby enabling switching the flow passages.

InFIG. 23, macromolecular materials of which the shaft sealing body is formed and which are used in the valve structure are shown. The macromolecular materials used in the valve structure can be expanded or deformed through external electro stimuli similarly in the case of the aforementioned shaft sealing device and includes at least three kinds of materials, i.e. one being an electro stimuli-responsive macromolecular material, another an electroconductive macromolecular material and the remainder an ionically conductive macromolecular material. The characteristics of these macromolecular materials are the same as those of the aforementioned macromolecular materials. Though the description of an electro stimuli-responsive macromolecular material having a section, other than a section to which external electro stimuli have been applied, deformed is omitted, this macromolecular material having an appropriate configuration can be utilized in the valve structure using the shaft sealing device, similarly to the three kinds of the macromolecular materials described herein below. The characteristics of the macromolecular material are the same as those of the aforementioned macromolecular material.

In the shaft sealing body using the electro stimuli-responsive macromolecular material or ionically conductive macromolecular material as the macromolecular material, a plate-shaped base is provided on the front and back surfaces thereof with electrodes, respectively and, in the case of using an electroconductive macromolecular material as the macromolecular material, there is no need to provide the front and back surfaces of the plate-like base with electrodes, but the plate-like base is molded into an annular shape. In addition, the shaft sealing body, if formed of an electro stimuli-responsive macromolecular material or an ionically conductive material, is provided on hollow cylindrical inner and outer peripheral surfaces thereof integrally with electrodes, respectively.FIGS. 24 to 26are schematic views showing a plate-shaped base material of a shaft sealing body formed into an annular shape.

The valve structure inFIG. 24has a shaft sealing body160A which is formed of an electro stimuli-responsive macromolecular material and which has a plate-like base material161A having electrodes162A and163A patterned on the outer and inner peripheries thereof. The base material161A is formed in a concentric hollow cylindrical shape. A separator168A formed of a material having compliant characteristics, such as a resin, is attached integrally to the outer periphery of the shaft sealing body160A to allow the separator168A and the shaft sealing body160A to be operated integrally.

A holder170A retains the shaft sealing body160A from the inner periphery thereof so that voltage may be applied from the exterior to the electrodes162A and163A of the shaft sealing body160A via communication holes171A and172A formed in the holder170A and through-holes164A and165A formed in the shaft sealing body160A. In addition, the shaft sealing body160A has the through-holes164A and165A fixed to the communication holes171A and172A of the holder170A to form a base166A and has a free end167A, opposite to the base166A, enabled to expansion-deform in the shape of a substantially perfect circle relative to the holder170A.

In the valve structure, when a power source not shown has been turned on and a potential difference has been given to between the electrodes162A and163A on the outer and inner peripheries of the tubular shaft sealing body160A, the shaft sealing body160A is deformed in a direction of being expanded in the axial direction. At this time, since the shaft sealing body160A has its surface on the side of the separator168A maintained, the shape of the inner periphery on the side opposite to the side of the separator168A is more expanded. Therefore, as shown inFIGS. 23 and 24(a), the shaft sealing body160A has the free end167A, except for the base166A, is deformed as being enlarged in diameter relative to the holder170A maintaining a reference cylindrical shape. In addition, when the potential difference has been eliminated, as shown inFIG. 24(b), the free end167A of the shaft sealing body is returned to the original position as being deformed to reduce its diameter along the holder170A.

Furthermore, the valve structure inFIGS. 25 and 26has a shaft sealing body160B formed of an electroconductive macromolecular material and, in this case, there is no need to provide the shaft sealing body with electrodes, and a base material161B is formed into a concentric hollow cylindrical shape. A separator168B is formed of a resin similarly to the case ofFIG. 24. The separator168B adheres integrally to the outer periphery of the shaft sealing body160B inFIG. 25and to the inner periphery of the shaft sealing body160B inFIG. 26.

A holder170B retains the shaft sealing body160B from the inner periphery thereof, and it is configured that voltage can be applied from the exterior to the outer and inner peripheral surfaces162B and163B of the shaft sealing body160B via communication holes171B and172B formed in the holder170B and through-holes164B and165B formed in the shaft sealing body160B. In addition, the shaft sealing body160B has the through-holes164B and165B fixed to the communication holes171B and172B of the holder170B to form a base166B, and a free end167B opposite to the base166B can be expanded or contracted, or deformed, in the shape of a substantially perfect circle relative to the holder170B.

In the valve structure ofFIG. 25, when a potential difference has been give to between the outer and inner peripheral surfaces162B and163B of the shaft sealing body160B, the shaft sealing body160is urged to expand in the axial direction. At this time, since the shape of the shaft sealing body160B on the side of the separator168B is maintained, the inner periphery of the shaft sealing device on the side opposite to the side of the separator168B is more expanded. As shown inFIGS. 23 and 25(b), therefore, the shaft sealing body160B has the free end167B, except for the base166, enlarged in diameter relative to and along the holder170A assuming the reference cylindrical shape. When the potential difference has been eliminated, as shown inFIG. 25(a), the free end167B is returned to the original position as being contracted.

On the other hand, in the valve structure ofFIG. 26, when a potential difference has been give to between the outer and inner peripheral surfaces162B and163B of the shaft sealing body160B, the shaft sealing body160B is urged to contract in the axial direction. At this time, since the shape of the shaft sealing body160B on the side of the separator168B is maintained, the outer periphery of the shaft sealing device on the side opposite to the side of the separator168B is more contracted. As shown inFIGS. 23 and 26(a), therefore, the shaft sealing body160B has the free end167B, except for the base166B, enlarged in diameter relative to the holder170B. When the potential difference has been eliminated, as shown inFIG. 26(b), the free end167B is returned to the original position as being expanded relative to and along the holder170B.

The valve structure inFIG. 27has a shaft sealing body160C formed of an ionically conductive macromolecular material and, similarly to the case of the electro stimuli-responsive macromolecular material, a plate-like base material161C has electrodes162C and163C patterned on the outer and inner peripheries thereof and is formed in a concentric hollow cylindrical shape. Similarly to the shaft sealing device ofFIG. 19, there is no need to attach a separator to the shaft sealing body160C. However, the separator may be attached as occasion demands.

A holder170C retains the shaft sealing body160C from the inner periphery thereof, and it is configured that voltage can be applied from the exterior to the electrodes162C and163C via communication holes171C and172C formed in the holder170C and through-holes164C and165C formed in the shaft sealing body160C. In addition, the shaft sealing body160C has the through-holes164C and165C fixed to the communication holes171C and172C of the holder170C to form a base166C, and a free end167C opposite to the base166C can be expanded or contracted, or deformed, in the shape of a substantially perfect circle relative to the holder170C.

In the valve structure ofFIG. 27, when a potential difference has been given to between the electrodes162C and163C on the outer and inner peripheries of the shaft sealing body160C, since the shaft sealing body160C has the inner peripheral surface expanded and the outer peripheral surface contracted, the free end167, except for the base166C, assumes a shape having the distal end thereof more expanded as shown inFIG. 27(a). In addition, when the potential difference has been eliminated, as shown inFIG. 27(b), the free end167C is returned to the original position as extending along the holder170C.

Next, the switching operation of the flow passages in the valve structure will be described using a typical example selected from the above examples.FIGS. 28 to 30show one example of the valve structure using the shaft sealing device. As shown inFIGS. 30(b) and30(c), a shaft sealing body160has front and back surfaces161aand161bof a base material161provided with electrodes162and163, respectively, and has the base material161molded into an annular shape as shown inFIG. 30(a).FIG. 30(b) is a development view having the shaft sealing body160developed, with line ab-a′b′ inFIG. 30(a) as a cutting-plane line, and a hatched portion in the figure denotes the electrode162. In addition,FIG. 30(c) is a development view showing the backside ofFIG. 30(a), and a hatched portion in the figure denotes the electrode163.

The electrodes162and163have belt-like electrodes162aand163a, respectively, each having a width one half the width of the shaft sealing body160in the axial direction and, when the shaft sealing body160is molded into a perfect circle, the belt-like electrodes162aand163aare formed on the front and back surfaces161aand162adescribing circumferences, respectively. Extraction electrodes162band163bdrawn from and connected to the belt-like electrodes162aand163a, respectively, are provided with through-holes164and165opposed to each other, whereby voltage can be applied to the entire electrodes from the through-holes164and165via the extraction electrodes162band163b. Since the configuration is such that voltage is applied to the electrodes162and163on the front and back surfaces via the through-holes164and165as described above, the electrodes162and163are not short-circuited, and it is possible to apply voltages of opposite polarities to the front and back surfaces161aand161bof the shaft sealing body160.

A holder170comprises a substantially circular portion170a, a diameter-increasing portion170bslightly larger in diameter than the cylindrical portion170aand a lid portion170clarger in diameter than the diameter-increasing portion170b. The cylindrical portion170ahas an outside diameter not shown but made slightly smaller than the inside diameter, not shown, of the shaft sealing body160and has the outer periphery thereof to which the shaft sealing body160can be attached. In addition, the diameter-increasing portion170bhas an outside diameter not shown but made substantially equal or slightly smaller than the inside diameter, not shown, of a device body150and can be inserted into the inside diameter of the device body150. The lid portion170chas an outside diameter capable of covering an opening end152of the device body150. Furthermore, the holder170is formed with communication holes171and172at positions corresponding to those of the through-holes164and165of the shaft sealing body160and, via the communication holes171and172, wires can be connected from the power supply circuit60to the electrodes162and163, respectively.

The power supply circuit60has the power source61and switch62and, when the switch62has been turned on, the circuit is closed to enable voltage to be applied to the electrodes162and163. The circuit60may be provided therein with a variable resistor not shown to enable the voltage to be adjusted. In addition, the polarities of the power source61are not limited to those shown inFIGS. 28 and 29, but may be vise versa.

The shaft sealing body160is attached to the position of the diameter-increasing portion170bof the holder170while subjecting the through-holes164and165and the communication holes171and172to alignment with each other, respectively, thereby enabling the shaft sealing body160to the holder170in an appropriately positioned state, and it is possible to connect the power supply circuit167from the inside of the holder170to the electrodes162and163via the communication holes171and172. This connection can be attained by connecting the electrode163to the extraction electrode163bon the inner peripheral side via the communication hole172, whereas the electrode162is connected to the extraction electrode162bon the outer peripheral side in a state in which the communication hole171and through hole164are allowed to communicate with each other.

After the connection of the power supply circuit60to the electrodes162and163, an appropriate fixing material is sealed in the through-holes164and165and communication holes171and172to fix a base166of the shaft sealing body160to the holder170. A free end167opposite to the base166can be deformed as being enlarged or reduced in diameter in the shape of a substantially perfect circle relative to the holder170. In addition, the sealed-in fixing material seals the through-holes and communication holes, thereby preventing a fluid from entering the holder170. Furthermore, the inside of the holder170may be filled with a potting material shown by two-dot chain lines.

The shaft sealing body160is inserted via the holder170into the device body150and, at the time the insertion, the diameter-increasing portion170bis inserted until the lid portion170cof the holder170is abutted on the opening end152of the device body, thereby obtaining the appropriate position enabling the free end167to be abutted on a seating face that constitutes a valve seal. In addition, since the opening end152is formed with an annular groove152ato which an O-ring154is attached, after the holder170and device body150are made integral with each other, the O-ring154seals between the device body150and the holder170to prevent a fluid from leaking between the two.

Furthermore, the cylindrical device body150is formed in the circumferential face direction with plural flow passages155and156communicating with the exterior, and the seating face153is provided between the flow passages155and156. In the valve structure, when external electro stimuli have applied to the shaft sealing body160, the free end167is expanded or contracted, or deformed, in the shape of a substantially perfect circle. By bringing the free end167that forms a shaft sealing portion into contact with or separating the same from the seating face153to obtain a shaft sealed state or fluid leakage state, thereby causing the flow passages155and156to be switchable.

When the switch62has been turned on from the state ofFIG. 28, voltages of opposite polarities are applied to the electrodes162and163. Since the shaft sealing body160is formed in a substantially cylindrical shape, with the opposite surfaces thereof provided with the electrodes162and163, and has the base166fixed to the holder170and the free end167, the shaft sealing body160is urged to deform as being enlarged in diameter in proportion as it goes to its distal end at the time of the application of voltage. As a result, the shaft sealing body160has the free end167enlarged in diameter in the circumferential direction more than the base166, i.e. assumes a shape widening toward the end (a trumpet shape). The shape in the diameter-enlarged state has a cross section in the direction orthogonal to the axis becomes a shape of a substantially perfect circle. The free end167of the shape of the substantially perfect circle is brought into circumferential pressure contact with the perfectly circular seating face153when higher voltage has been applied thereto to close between the passages155and156, thereby enabling the shaft sealed state to be obtained. Furthermore, by controlling the applied voltage to be lowered little by little from the shaft sealed state, the minute leakage amount can be adjusted to the prescribed flow rate to enable the shaft sealing body160to be operated as a valving element.

On the other hand, when the switch has been turned off from the state ofFIG. 29, the shaft sealing body160is in a nonconductive state and, as shown inFIG. 28, the free end167is returned to the original state in which it is deformed as being reduced in diameter and the entire shaft sealing body160assumes the substantially tubular shape. This deformation forms a gap between the shaft sealing body160and the device body150to allow the flow passages155and156to communicate with each other to enable the fluid to flow.

At this time, in order for the free end167to establish the shaft sealed state with exactitude, it is necessary process the seating face153with high precision to enhance the surface roughness and the dimensional precision including circularity and select a material suitable for sealing relative to the shaft sealing body160to form the device body150so as not to induce leakage. In this case, the device body is fabricated so that a gap between the device body150and the shaft sealing body160when the shaft sealing body160has been reduced in diameter may be around 0.5 mm and, as a result, a fluid can flow at the time of the diameter reduction and minute leakage induced when the shaft sealing body160has been enlarged or contracted in diameter can be controlled with high precision.

Incidentally, the shaft sealing body formed of the ionically conductive macromolecular material has been described in the valve structure using the shaft sealing device in this example. However, it goes without saying that the shaft sealing body may be formed of an electro stimuli-responsive macromolecular material, an electroconductive macromolecular material, an electro stimuli-responsive macromolecular material having a section, other than a section to which external electro stimuli have been applied, deformed, or other macromolecular material. In this case, a valve structure is adopted to meet each of the macromolecular materials to be used. When the shaft sealing body is formed of an electroconductive macromolecular material, for example, there is no need to provide the shaft sealing body with electrodes. In addition, when the shaft sealing body is formed of an electro stimuli-responsive macromolecular material or an electroconductive macromolecular material, a flexible separator169is attached to the macromolecular material on the side of the outer or inner periphery of the shaft sealing body160.

FIGS. 31 to 33show an example in which the valve structure using the shaft sealing device is applied to a multiway valve. In the valve structure, a shaft sealing body190is formed of an ionically conductive macromolecular material and has a substantially central neighborhood thereof serving as a base196fixed to a cylindrical portion201of a holder200and opposite ends thereof serving as free ends197and198. As shown inFIG. 33, the shaft sealing body190has front and back surfaces191aand191bof the axial opposite ends provided with belt-like electrodes192aiand192a2and belt-like electrodes193aiand193a2, respectively, and extraction electrodes192b1,192b2,193b1and193b2extend from the belt-like electrodes192ai,192a2,193aiand193a2to the axial central neighborhood, thereby constituting electrodes192and193. At this time, electrodes of the same polarity are disposed on different ends of the front and back surfaces191aand191bof the shaft sealing body190via one through-hole, and voltages of the same polarity can be applied from one through-hole to the electrode on the front surface191aof one end and to the electrode on the back surface191bof the other end.

For example, since a through-hole194is connected to the extraction electrodes192b1and192b2and since the extraction electrodes192b1and192b2are connected to belt-like electrodes192aiand192a2, it is possible to apply voltage from the through-hole194to the electrodes192and192on the front and back surfaces at the same time. On the other hand, since electrodes are similarly configured with respect to a through-hole195, voltage can simultaneously be applied from the through-hole195to the electrodes193and193on the front and back surfaces. Furthermore, in this example, since the polarities of a power supply circuit not shown can be switched, voltages of opposite polarities can be applied to the electrodes192and193, respectively.

A device body180has three flow passages185,186and187formed therein in a circumferential direction and two inner cylindrical annular portions (seating faces)183and184formed on the inner periphery thereof and sandwiched between the adjacent two of the three flow passages185,186and187. When the shaft sealing body190has been inserted into the device body180via the holder200, the two free ends197and198are disposed at the positions of the two inner cylindrical annular portions183and184and, when voltage has been applied to expand or contract the free ends197and198, the free ends197and198are brought into contact with or separated from the inner cylindrical annular portions183and184, as shaft sealing portions, thereby enabling switching the flow passages185,186and187.

FIG. 31shows a state, in which voltages have been applied to the front and back surfaces of the free end197so that the front side of the free end197may be contracted relative to the shaft sealing body190and the back side thereof may simultaneously be expanded relative to the same. At this time, the free end197is brought into pressure contact with the inner cylindrical annular portion183while being enlarged in diameter and maintaining the shape of a substantially perfect circle, thereby obtaining a shaft-sealed state. On the other hand, since voltage of an opposite polarity to that applied to the free end197has been applied to the front and back surfaces of the free end198, the free end198is urged to have the front side expanded and the back side contracted. As a result, the free end198is contracted in the inside diameter direction and brought to a state in which the free end is separated from the inner cylindrical annular portion184. Consequently, a space between the flow passages185and186is shaft-sealed with a circumferential seal by the free end197, whereas a gap is formed between the flow passages186and187communicating with each other to enable a fluid to flow from the flow passage186to the flow passage187as shown in the figure.

On the other hand, inFIG. 32, the polarities of voltages from the power supply circuit are switched to apply voltage of a polarity, which enables the front surface of the free end197to be expanded and the back surface thereof to be contracted, to the free end and apply voltage of a polarity, which enables the front surface of the free end198to be contracted and the back surface thereof to be expanded, to the free end. In this case, the free end197is contracted in the inside diameter direction to separate from the inner cylindrical annular portion, whereas the free end198is urged to enlarge its diameter while maintaining the shape of a substantially perfect circle. Consequently, a gap is formed between the flow passages185and186and, at the same time, a space between the flow passages186and187is shaft-sealed to enable a fluid to flow from the flow passage186to the flow passage185. With this valve structure, since it is possible to seal the inner cylindrical annular portions183and184of the cylindrical device body180and switch the fluid from the flow passage186to the flow passage185or187, it is possible to provide an on-off valve having a simple and compact structure and capable of being fabricated at low cost.

Incidentally, when the opposite ends of the shaft sealing body are made free, by forming the shaft sealing body of the ionically conductive macromolecular material or electro stimuli-responsive macromolecular material having a section, other than a section to which external electro stimuli have been applied, deformed, as is done in this embodiment, the application of voltage enables the opposite side free ends to be expanded and contracted, respectively, even in the case where the front and back surfaces of the base material are provided with electrodes of opposite polarities at the opposite free ends. This is because the ionically conductive macromolecular material can reverse its deformation (expansion or contraction) direction by changing the polarity of the voltage to be applied. When using an electro stimuli-responsive macromolecular material or electroconductive macromolecular material and making the opposite ends free, however, the deformation direction or expansion or contraction direction of the macromolecular materials at the time of performing or stopping the application voltage is decided irrespective of a difference in polarity, it is impossible that the opposite free ends of a single base material are deformed (expanded or contracted) in different directions. Therefore, when using each of these macromolecular materials and making the opposite ends free, two base materials of the same material are attached to the inner or outer peripheral surface of the macromolecular material to obtain an integral body, an electrode is disposed on each of the base materials and, with this state maintained, the entirety is attached to the holder.

Subsequently,FIGS. 34 and 35show another example in which the valve structure using the shaft sealing device is applied to a multiway valve. In this example, the valve structure has two shaft sealing devices ofFIG. 31continuously disposed in the axial direction, and the free end of each shaft sealing body is used as a shaft sealing portion that is brought to a shaft-sealed state or fluid leakage state, thereby making a large number of fluid passages switchable.

In the valve structure, a device body210is formed with five flow passages216,217,218,219and220in the circumferential direction and four inner cylindrical annular portions (seating faces)212,213,214and215each sandwiched between adjacent two of the flow passages216,217,218,219and220. The holders200each having the shaft sealing body190attached thereto are inserted from two opening ends211aand211binto the device body210, respectively, to bring the free ends197and198of the shaft sealing bodies190and190into contact with or separate them from the inner cylindrical annular portions212,213,214and215, thereby making it possible to switch the five flow passages. In addition, different power supply circuits are connected to the shaft sealing bodies190to enable the shaft sealing bodies190to be operated individually.

InFIG. 34, voltages of polarities capable of contracting the free end197of the upper shaft sealing body190in diameter and, at the same time, enlarging the free end198in diameter are applied from the power supply circuits, and voltages of polarities capable of contracting the free end197of the lower shaft sealing body190in diameter and, at the same time, enlarging the free end198are applied from the power supply circuits. In this case, the flow passages218and219are allowed to communicate with each other, the flow passages216and217are also allowed to communicate with each other, and spaces between other flow passages are brought to a shaft-sealed state. As a result, a fluid can be flowed from the flow passage218to the flow passage219and from the flow passage217to the flow passage216.

On the other hand, inFIG. 35, voltages of polarities capable of enlarging the free end197of the upper shaft sealing body190in diameter and, at the same time, contracting the free end198in diameter are applied from the power supply circuits, and voltages of polarities capable of enlarging the free end197of the lower shaft sealing body190in diameter and, at the same time, contracting the free end198are applied from the power supply circuits. In this case, the flow passages218and217are allowed to communicate with each other, the flow passages219and220are also allowed to communicate with each other, and spaces between other flow passages are brought to a shaft-sealed state. As a result, a fluid can be flowed from the flow passage218to the flow passage217and from the flow passage219to the flow passage220.

In the valve structure using the shaft sealing device, therefore, by connecting an air supply opening and an exhaust opening of an air pressure operable actuator not shown to the flow passages217and219, for example, when compressed air has been supplied from the flow passage218in the state ofFIG. 34, it is possible to send the compressed air to a first air chamber of a cylinder not shown via the flow passage219and, at the same time, exhaust the compressed air from a second air chamber disposed across a piston within the cylinder via the flow passage217out of the flow passage216.

In addition, when compressed air has been supplied from the flow passage218, with the flow passages switched to the state ofFIG. 35, it is possible to supply the compressed air to the second air chamber via the flow passage217and, at the same time, exhaust the compressed air from the first air chamber via the flow passage219out of the flow passage220.

Thus, the valve structure using the shaft sealing device is used as an electromagnetic changeover valve, for example, to enable controlling the operation of the actuator and, as described above, it is possible to use the free end of the shaft sealing body as the shaft sealing portion that is brought into contact with or separated from at least two inner cylindrical annular portions (seating faces), thereby making it possible to switch the flow passages. In addition, a multiway valve can be provided through disposing two or more shaft sealing bodies within the device body.

Incidentally, in this example, since the flow passages216,217,218,219and220are formed in different circumferential directions of the device body and, as a consequence, this example can be applied to all kinds of multiway valves. In addition, in each of the examples described above, the base of the shaft sealing body is attached to the holder. However, the shaft sealing body can be fixed to the device body and, also in this case, the shaft-sealed state or fluid leakage state can be obtained in the same manner as described above.

Next, the practicability of each of the shaft sealing device and the valve structure according to the present invention was examined through the simulation of the deformation state of the shaft sealing body of the present invention by the CAE analysis. Since it was difficult to confirm the state of deformation of an actual shaft sealing body when having been expanded or contracted, an analysis of the state of deformation of a workpiece was made by the CAE analysis. The results of the analysis were substituted for the deformations of the actual shaft sealing body when having been expanded or contracted. The CAE analysis method included the steps of giving a temperature difference to between the inner and outer peripheries of the workpiece and confirming the state of deformations when having been expanded or contracted due to the temperature difference.

The workpieces used in the analysis are shown inFIGS. 36 and 37. As shown inFIG. 36, the workpiece A was a single layer of cylinder having dimensions of 7 mm in outside diameter, 5 mm in inside diameter and 10 mm in height at 24.85° C. (normal temperature) and having one end thereof constrained and the other end thereof made free, expansible and contractible. The conditions of constraint included the steps of dividing the height of 10 mm into two sections H1and H2, constraining both the inner and outer peripheries of the section H1and making both the inner and outer peripheries of the section H2free. The workpiece A was used to simulate the movements of the shaft sealing body160formed of an ionically conductive macromolecular material as shown inFIG. 28and make analyses through substitution of the section H1for the neighborhood of the base166of the shaft sealing body160and of the section H2for the neighborhood of the free end167.

On the other hand, the workpiece B shown inFIG. 37had the same dimensions as the workpiece A, was axially divided into two members X 7 mm in outside diameter (6 mm in inside diameter) and Y 6 mm in outside diameter (5 mm in inside diameter) and integrally combining the two members X and Y together. At that time, a heat-insulating layer 0.1 mm in thickness not shown was allowed to intervene between the members X and Y in order to prevent heat transfer between the respective members. The conditions of constraint of the workpiece B included the steps of dividing the height of 10 mm into two sections H3and H4, constraining both the inner and outer peripheries of the section H3and making both the inner and outer peripheries of the section H4free, similarly to the case of the workpiece A. The workpiece B was used to simulate the movements of the shaft sealing body160ofFIG. 28formed of an electro stimuli-responsive macromolecular material or an electroconductive macromolecular material in the case of using the separator169, allow the shaft sealing body160to serve as the member Y and the separator169to serve as the member X and make analyses through the substitution of the section H3for the neighborhood of the base166and the section H4for the neighborhood of the free end167.

The material for each workpiece might have an appropriate linear coefficient of expansion and, when it was TFE (tetrafluoroethylene), for example, the linear coefficient of expansion thereof was 79.0×10−5/° C. at 20° C., 20.0×10−5/° C. at 0° C., 16.0×10−5/° C. at 30° C., 12.4×10−5/° C. at 50° C. and 13.5×10−5/° C. at −50° C., for example. As the linear coefficient of expansion thereof at a set temperature having no temperature value, the value obtained by the regression calculation was adopted. In addition, the Poisson ratio of each workpiece before and after the deformation thereof was set to be 0.46.

The temperatures set for sections during heat transfer to the workpiece A are shown in Table 1. At that time, the inner periphery of the workpiece A was expressed as the inner avoiding surface on the inner periphery and the outer periphery thereof as the outer avoiding surface on the outer periphery, and the combinations of the temperatures on these surfaces were as shown in the table.

The temperatures set for sections during heat transfer to the workpiece B are shown in Table 2. The entire members X and Y of the workpiece B were give temperatures, respectively. This was because the state of deformations made by giving relative temperature differences to the inner and outer peripheries of the workpiece B was substituted for the state of deformations of the shaft sealing body and the separator in the shaft sealing body having the separator attached thereto.

The state of each of the workpieces A and B was, as shown in the schematic view ofFIG. 38when the inner periphery was set at low temperatures (minus temperatures) and the outer periphery at high temperatures (plus temperatures), such that a distal end (free end)230of each workpiece had a diameter shape contracted more in proportion as it went toward the distal end side while maintaining a shape of a substantially perfect circle. At that time, that tendency was further strengthened in the case where the temperature difference between the inner and outer peripheries became larger.

For example, the maximum amount of deformation (the amount of contraction in diameter) of the free end in set temperature No. 2 of the workpiece A became 0.008 mm at the inside diameter side, and that of the free end in set temperature No. 3 having a larger temperature difference became 0.015 mm. In addition, the maximum amount of deformation of the free end in set temperature No. 7 of the workpiece B became 0.008 mm, and that of the free end in set temperature No. 8 having a larger temperature difference became 0.013 mm.

On the other hand, when the inner periphery of each of the workpieces A and B was set at high temperatures (plus temperatures) and the outer periphery thereof at low temperatures (minus temperatures), as shown in the schematic view ofFIG. 39, a distal end230′ of each workpiece assumed a diameter shape expanded more in proportion as it went toward the distal (upper) end side, i.e. a shape substantially widening toward the end. Also in that case, hat tendency was further strengthened when the temperature difference between the inner and outer peripheries became larger.

For example, the maximum amount of deformation (the amount of expansion in diameter) of the free end in set temperature No. 4 of the workpiece A became 0.010 mm at the outside diameter side, and that of the free end in set temperature No. 5 having a larger temperature difference between the inner and outer peripheries became 0.015 mm. In addition, the maximum amount of deformation of the free end in set temperature No. 9 of the workpiece B became 0.008 mm, and that of the free end in set temperature No. 10 having a larger temperature difference became 0.013 mm.

As described above, obtained were analysis results in either the workpiece A or the workpiece B that by making the temperature on the inner periphery lower than on the outer periphery, the distal end of the work could uniformly be reduced in diameter in the shape of a substantially perfect circle and that by changing the temperature difference states on the inner and outer peripheries, i.e. making the temperature on the inner periphery higher than on the outer periphery, free end (distal end) of the workpiece could uniformly be enlarged in diameter in the shape of a substantially perfect circle. When the analysis results were applied to the shaft sealing body of the above embodiment, by applying voltages of opposite polarities to the front and back surfaces of the shaft sealing body, it could be said that the shape was changed by expansion or contraction, or deformation, while maintaining a cross-sectional shape of a perfect circle. Thus, by simulating, through the CAE analysis, the state of change of the shaft sealing body at the time external electro stimuli were applied, it could be verified that the shaft sealing body was a suitable material for the shaft sealing structure and the valve structure according to the present invention.

Subsequently, in order to confirm whether the deformation mode of an electro stimuli-responsive macromolecular material having a section, other than a section to which external electro stimuli were applied, deformed was applicable to the shaft sealing device, predetermined voltage was applied and the resultant amount of displacement was measured. This measurement was performed using a displacement measurement device240shown inFIG. 40.

The displacement measurement device240has a movable stand242for fixing a measured body (a gel sheet sold under the trade name Hitohada (registered trademark) and product code H0-1)241and a stage243capable of moving the stand242. In addition, a high-voltage power supply (sold under the type of HJPQ-30P1 and manufactured by Matsusada Precision Inc.)244is connected to fixed electrodes not shown for clamping the measured body241to enable the application of voltage to the measured body241. A laser displacement gauge (sold under the type of LJ-G080 and manufactured by Keyence Corporation)245irradiates the measured body241with a laser L to enable the measurement of the amount of bending displacement of the measured body241.

First, before the measurement, the measured body241was clamped by the fixed electrodes of the displacement measurement device240and fixed to the stand242. In addition, the movable stage243was used to adjust the distance between the measured body241and the laser displacement gauge245.

The high-voltage power supply244was operated, with the above state maintained, to stepwise increase the voltage from 0 V to 7 kV by 1 kV per 20 sec. to be applied to the measured body241as shown inFIG. 41(a) and, during the operation, the amount ∈ of bending displacement of the measured body241was measured with the laser displacement gauge245.FIG. 41(b) shows the states of a current under the application of the voltage.

FIG. 42shows the movement of the measured body at the time of applying voltage. As shown inFIG. 42(a), the measured body241was bent and deformed from the foot thereof toward a negative electrode by the application of voltage and, at that time, the distance from an end face241aof the measured body241when no voltage (0 V) was applied to a corner241bthereof when voltage was applied was defined as the amount ∈ of displacement. The transition of the amount ∈ of displacement is shown by a graph inFIG. 41(c).

The displacement of the measured body241was confirmed fromFIG. 41when the voltage applied reached 4 kV. Furthermore, when the applied voltage reached 7 kV, the amount ∈ of displacement was about 1.15 mm that was the maximum value. In addition, when the applied voltage was decreased from the state of 7 kV to the state of no voltage (0 V), it was confirmed that the measured body241was returned to the initial shape (before the voltage was applied).

It was confirmed from the above measurement results that the electro stimuli-responsive macromolecular material of which the measured body241was formed was suitable for use in the shaft sealing device of the present invention because the maximum amount of deformation thereof under the above conditions was 1.15 mm that was a large value. In that case, the measured body241was bent toward the negative electrode when the voltage was applied thereto. When turning over the polarity, however, it was confirmed that the bending direction was reversed (toward the positive electrode). In actual use, therefore, the measured body can be bent in a desired bending direction through adoption of the condition described above. In addition, in the above case, since the measured body241is bent and deformed at the time of the application of voltage to form a gap by the amounts of deformation, the electro stimuli-responsive macromolecular material is utilized to constitute an NC seal device. Furthermore, an NO seal device can be constituted by beforehand setting that the electro stimuli-responsive macromolecular material is molded into a bent shape in an initial state and deformed into a plane shape when voltage has been applied.