Liquid state detecting sensor

Abstract

The present invention provides a liquid state detecting sensor that is free from a problem of increase in the number of parts and a problem in assembly and furthermore capable of, in support of electrodes, absorbing an error and supporting both electrodes, even in case an inner electrode has at a surface an insulation layer, without causing any damage to the layer. The liquid state detecting sensor includes an outer tubular electrode 10 shaped tubular and formed from a conductor, an inner electrode 20 in the form of a shaft and disposed along an axial direction G and within the outer tubular electrode, and a base end support member 40 that supports, at base end sides of the both electrodes 10 and 20 , the both electrodes 10 and 20 while holding the electrodes insulated from each other, and detects a level of liquid within a tank 1 , etc. by measuring an electrostatic capacity between the electrodes, wherein an elastic body 30 made of rubber is disposed, by insertion under pressure, at a place outside a leading end or its adjacent portion of the inner electrode 20 and inside the outer tubular electrode 10 . Since the leading end or its adjacent portion of the inner electrode 20 is elastically supported on an inside of the outer tubular electrode 10 , the assembly can be attained with ease and the dimensional error of the parts and vibrations thereof can be absorbed.

1 - 11 . (canceled) 
   
   
       12 . A sensor for detecting a state of liquid contained in a container comprising:
 an outer tubular electrode made of an electrically conductive material;   an inner electrode made of an electrically conductive material and disposed concentrically within the outer tubular electrode:   a base end support member supporting base end portions of the outer tubular electrode and the inner electrode in a way as to provide insulation therebetween; and   a leading end support member elastically supporting a leading end portion of the inner electrode on an inside of a leading end portion of the outer tubular electrode.   
   
   
       13 . A sensor according to  claim 12 , wherein the leading end support member includes an elastic body and is configured so as to be inserted under pressure into a space between the leading end portions of the outer tubular electrode and the inner electrode. 
   
   
       14 . A sensor according to  claim 13 , wherein the leading end support member has at an outer circumferential surface an outward protrusion, and the outer tubular electrode has at the leading end portion a through hole in which the outward protrusion of the leading end support member is fitted. 
   
   
       15 . A sensor according to  claim 14 , wherein the protrusion of the leading end support member has an inclined outer surface portion, the protruding amount of which inclined outer surface portion in the radial direction of the leading end support member reduces gradually in the direction in which the leading end support member is inserted under pressure. 
   
   
       16 . A sensor according to  claim 14 , wherein the protrusion of the leading end support member has an inclined outer surface portion, the protruding amount of which inclined outer surface portion in the radial direction of the leading end support member reduces gradually in the direction in which the leading end support member is inserted under pressure, the inclined outer surface portion having at an end which constitutes a maximumly protruded section a chamfer, the protruding amount of which chamfer in the radial direction of the leading end support member reduces gradually in the direction opposite to the direction in which the leading end support member is inserted under pressure. 
   
   
       17 . A sensor according to  claim 12 , wherein the leading end support member has at an inner circumferential surface a plurality of inward protrusions that are arranged with angular intervals and configured to support the leading end portion of the inner electrode. 
   
   
       18 . A sensor according to  claim 17 , wherein the inward protrusions have guides for guiding insertion of the inner electrode into the leading end support member, the guides being so shaped as to flare in the direction in which the leading end support member is inserted under pressure. 
   
   
       19 . A sensor according to  claim 18 , wherein each of the guides includes a rounded chamfer. 
   
   
       20 . A sensor according to  claim 18 , wherein each of the guides includes an oblique chamfer. 
   
   
       21 . A sensor according to  claim 17 , wherein the leading end support member has a bottomed tubular shape and includes a through hole at a bottom and communication recesses between the inward projections, the through hole and the communication recesses cooperating with each other to constitute a flow passage through which the liquid flows into and out of the outer tubular electrode. 
   
   
       22 . A sensor according to  claim 12 , wherein the inner electrode has at a surface thereof an insulation layer. 
   
   
       23 . A sensor according to  claim 13 , wherein the leading end support member has a bottomed-tubular shape and further includes a non-elastic core member embedded in the elastic body. 
   
   
       24 . A sensor according to  claim 23 , wherein the core member is ring-shaped. 
   
   
       25 . A sensor according to  claim 13 , wherein the elastic body is made of rubber. 
   
   
       26 . A sensor according to  claim 12 , wherein the leading end support member has a bottomed tubular shape and is disposed between the leading end portions of the outer tubular electrode and the inner tubular electrode, the leading end support member including a non-elastic main body and an elastic body disposed at one of an outer circumferential surface and an inner circumferential of the non-elastic main body. 
   
   
       27 . A sensor according to  claim 26 , wherein the elastic body is in the form of an O-ring. 
   
   
       28 . A sensor according to  claim 26 , wherein the elastic body is made of rubber. 
   
   
       29 . A sensor according to  claim 26 , wherein the non-elastic main body is made of metal. 
   
   
       30 . A sensor according to  claim 26 , wherein the non-elastic main body is made of hard resin. 
   
   
       31 . A sensor according to  claim 12 , wherein the liquid is urea water.