Shaft sealing device and valve structure using the same

Abstract

A shaft sealing device with a simple internal structure 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. 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.

1 . 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 electrostimuli 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.   
   
   
       2 . A shaft sealing device according to  claim 1 , 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. 
   
   
       3 . A shaft sealing device according to  claim 1 , 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. 
   
   
       4 . A shaft sealing device according to  claim 1 , 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. 
   
   
       5 . A shaft sealing device according to  claim 1 , 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. 
   
   
       6 . A shaft sealing device according to  claim 1 , 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. 
   
   
       7 . A shaft sealing device according to  claim 1 , 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. 
   
   
       8 . A shaft sealing device according to  claim 1 , 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. 
   
   
       9 . A shaft sealing device according to  claim 1 , 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. 
   
   
       10 . A shaft sealing device according to  claim 2 , wherein the leakage phenomenon includes a minute leakage phenomenon. 
   
   
       11 . 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.   
   
   
       12 . A shaft sealing device according to  claim 11 , 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 front and back surfaces provided respectively with electrodes. 
   
   
       13 . A shaft sealing device according to  claim 11 , 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. 
   
   
       14 . A valve structure using the shaft sealing device according to  claim 11 , 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. 
   
   
       15 . A valve structure according to  claim 14 , 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. 
   
   
       16 . A valve structure according to  claim 14 , 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.