Patent Publication Number: US-2023157528-A1

Title: Rigidity variable apparatus, endoscope, and manufacturing method of rigidity variable apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation application of PCT/JP2020/027370 filed on Jul. 14, 2020, the entire contents of which are incorporated herein by this reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a rigidity variable apparatus including a rigidity variable member having a cylindrical shape, a bending rigidity of which increases by being heated by a heater, and also relates to an endoscope and a manufacturing method of the rigidity variable apparatus. 
     2. Description of the Related Art 
     In recent years, endoscopes have been widely used in medical fields and industrial fields. Endoscopes are capable of performing observation, various kinds of treatment, and the like, of an inside of a subject or an object by inserting an elongated insertion portion into the subject or the object. 
     A known technique is to vary a rigidity of a flexible tube portion, which is provided on a proximal end side with respect to a bending portion, in an insertion portion of an endoscope. 
     Specifically, a configuration is known in which a rigidity variable apparatus is provided in a flexible tube portion, to allow the rigidity of the flexible tube portion to be variable by using the rigidity variable apparatus. 
      Also a configuration is known in which a plurality of rigidity variable apparatuses are provided in a flexible tube portion along a longitudinal axis direction of the flexible tube portion, and a bending rigidity of the flexible tube portion is increased, that is, the flexible tube portion is hardened, sequentially from a distal end toward a proximal end in the longitudinal axis direction by using the respective rigidity variable apparatuses. 
     Furthermore, as a known example of a rigidity variable apparatus, the rigidity variable apparatus has a configuration using a rigidity variable member, for example, a shape memory alloy (SMA), a bending rigidity of which increases by being heated. 
     A shape memory alloy has such a property that a given part can be hardened by being heated using a heater and can be softened by cooling. 
     In order to improve a hardening speed of a shape memory alloy, there has been a need for improving a heat transfer performance (efficiency) from the heater to the shape memory alloy. 
     In view of such a circumstance, WO2018/189888 discloses a rigidity variable apparatus having a configuration in which a cylindrical heater for heating a shape memory alloy is provided on an inside of a cylindrical shape memory alloy in a radial direction, a bending rigidity of the shape memory alloy increasing by being heated. 
     With such a configuration, the heater directly heats the shape memory alloy, to thereby be capable of improving the heat transfer performance from the heater to the shape memory alloy. As a result, the shape memory alloy can be hardened quickly. 
     SUMMARY OF THE INVENTION 
     A rigidity variable apparatus according to one aspect of the present invention includes: a rigidity variable member having a cylindrical shape, a bending rigidity of the rigidity variable member increasing by being heated; a heater having a cylindrical shape and arranged along the rigidity variable member on an inside of the rigidity variable member in a radial direction, the heater being configured to heat the rigidity variable member; a filler arranged so as to fill a gap between the heater and the rigidity variable member in the radial direction, the filler being configured to transfer heat from the heater to the rigidity variable member; and a tube arranged along the heater on an inside of the heater in the radial direction. 
     Further, an endoscope according to one aspect of the present invention includes: an insertion portion; and a rigidity variable apparatus provided in the insertion portion. The rigidity variable apparatus includes: a rigidity variable member having a cylindrical shape, a bending rigidity of the rigidity variable member increasing by being heated; a heater having a cylindrical shape and arranged along the rigidity variable member on an inside of the rigidity variable member in a radial direction, the heater being configured to heat the rigidity variable member; a filler arranged so as to fill a gap between the heater and the rigidity variable member in the radial direction, the filler being configured to transfer heat from the heater to the rigidity variable member; and a tube arranged along the heater on an inside of the heater in the radial direction. 
     Furthermore, a manufacturing method of a rigidity variable apparatus according to one aspect of the present invention includes: filling a filler into an inside of a rigidity variable member in a radial direction, the rigidity variable member being formed in a cylindrical shape having a first opening at one end portion, a bending rigidity of the rigidity variable member increasing by being heated, the filler being filled through the first opening; and passing a heater unit having a cylindrical shape through the first opening and pushing the heater unit into the inside of the rigidity variable member, the heater unit including a heater having a cylindrical shape and a tube arranged on an inside of the heater in the radial direction, to arrange the filler so as to fill a gap between an inner circumferential surface of the rigidity variable member and the heater. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a view schematically showing an appearance of an endoscope including, in a flexible tube portion of an insertion portion thereof, rigidity variable apparatuses according to a first embodiment. 
         FIG.  2    is a cross-sectional view of one of the rigidity variable apparatuses provided in the flexible tube portion of the insertion portion of the endoscope in  FIG.  1   . 
         FIG.  3    is a cross-sectional view of the rigidity variable apparatus having a configuration ideal for quickly hardening a rigidity variable member in  FIG.  2   . 
         FIG.  4    is a cross-sectional view showing a state where a filler has been filled into an inside of a heater in  FIG.  3   . 
         FIG.  5    is a cross-sectional view showing a state where the filler is filled into an inside of the rigidity variable member in a radial direction. 
         FIG.  6    is a cross-sectional view showing a state where a heater unit in  FIG.  2    is pushed into the inside of the rigidity variable member in  FIG.  5   . 
         FIG.  7    is a cross-sectional view of a rigidity variable apparatus according to a second embodiment. 
         FIG.  8    is a cross-sectional view showing a state where a heater unit in  FIG.  7    is pushed into the inside of the rigidity variable member in  FIG.  5   . 
         FIG.  9    is a cross-sectional view showing a state where conductive wires are extended respectively from one end and another end of a heater in the rigidity variable apparatus in  FIG.  2   . 
         FIG.  10    is a cross-sectional view showing a state where conductive wires are extended respectively from one end and another end of a heater in the rigidity variable apparatus in  FIG.  7   . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     Hereinafter, embodiments of the present invention will be described with reference to drawings. Note that, in the embodiments to be described below, description will be made on an endoscope by taking a colonoscope for medical use as an example. 
     First Embodiment 
       FIG.  1    is a view schematically showing an appearance of an endoscope including, in a flexible tube portion of an insertion portion thereof, rigidity variable apparatuses according to the present embodiment. 
     As shown in  FIG.  1   , an endoscope  1  has a main part configured by including: an insertion portion  2  configured to be inserted into a subject; an operation portion  3  provided continuously with a proximal end side of the insertion portion  2  in a longitudinal axis direction N; a universal cord  8  extended from the operation portion  3 ; and a connector  9  provided at an extension end of the universal cord  8 . 
     Note that the endoscope  1  is electrically connected to external apparatuses such as a control apparatus and an illumination apparatus, through the connector  9 . 
     The operation portion  3  is provided with a bending knob  4  and a bending knob  6 . The bending knob  4  is configured to bend a bending portion  2   w , to be described later, of the insertion portion  2  in up and down directions. The bending knob  6  is configured to bend the bending portion  2   w  in left and right directions. Furthermore, the operation portion  3  includes a fixing lever  5  and a fixing knob  7 . The fixing lever  5  is configured to fix a rotation position of the bending knob  4 . The fixing knob  7  is configured to fix a rotation position of the bending knob  6 . 
     Furthermore, the operation portion  3  is provided with a rigidity variable switch  11  configured to harden a rigidity variable member  60  (see  FIG.  2   ) of each of rigidity variable apparatuses  100  provided in a flexible tube portion  2   k , to be described later, of the insertion portion  2 . 
     The insertion portion  2  is configured of a distal end portion  2   s , the bending portion  2   w , and the flexible tube portion  2   k , and is formed in an elongated shape along the longitudinal axis direction N. 
     The distal end portion  2   s  includes, inside thereof, an image pickup unit configured to observe an inside of a subject, an illumination unit configured to illuminate the inside of the subject (neither of them is shown), and the like. 
     The bending portion  2   w  is configured to be bent in four directions, for example, up, down, left, and right directions, by rotational operations of the bending knob  4  and the bending knob  6 , to thereby vary the observation direction of the image pickup unit provided in the distal end portion  2   s  and improve an insertion performance of the distal end portion  2   s  in the subject. 
     Furthermore, the flexible tube portion  2   k  is provided continuously with a proximal end side of the bending portion  2   w . In the flexible tube portion  2   k , one or a plurality of rigidity variable apparatuses  100  are provided along the longitudinal axis direction N. 
     Note that  FIG.  1    shows a case where five rigidity variable apparatuses  100  are provided in the flexible tube portion  2   k . However, it is needless to say that the number of the rigidity variable apparatuses  100  is not limited to five. The rigidity variable apparatuses  100 , the number of which corresponds to a size of a region a rigidity of which is desired to be varied, may be provided in the flexible tube portion  2   k  along the longitudinal axis direction N of the flexible tube portion  2   k . 
     Next, description will be made on the configuration of the rigidity variable apparatus  100  with reference to  FIGS.  2  to  4   . 
       FIG.  2    is a cross-sectional view of one of the rigidity variable apparatuses provided in the flexible tube portion of the insertion portion of the endoscope in  FIG.  1   .  FIG.  3    is a cross-sectional view of the rigidity variable apparatus having a configuration ideal for quickly hardening the rigidity variable member in  FIG.  2   .  FIG.  4    is a cross-sectional view showing a state where a filler has been filled into an inside of the heater in  FIG.  3   . 
     As shown in  FIG.  2   , the rigidity variable apparatus  100  has a main part configured by including the rigidity variable member  60 , a heater unit  50 , and a filler  30 . 
     The rigidity variable member  60  is formed in an elongated and cylindrical shape along the longitudinal axis direction N. In addition, the rigidity variable member  60  has a first opening  60   h   1  at one end portion  60   a  in the longitudinal axis direction N and has an opening  60   h   2  at another end portion  60   b  in the longitudinal axis direction N. The opening  60   h   2  of the rigidity variable member  60  is closed, and therefore, the rigidity variable member  60  has a recessed shape in a landscape orientation in  FIG.  2   . 
     Note that the first opening  60   h   1  is sealed by an adhesive, or the like, not shown. In addition, also the opening  60   h   2  of the rigidity variable member  60  formed in a cylindrical shape may be sealed by an adhesive, or the like, not shown. 
     The rigidity variable member  60  is a member, the rigidity of which increases by being heated and which is made of a known shape memory alloy, the bending rigidity of which increases by being heated by a heater  51  to be described later. 
     The heater unit  50  is formed in an elongated and cylindrical shape along the longitudinal axis direction N, and is constituted of the heater  51  and a tube  52 . 
     The heater  51  is formed in an elongated and cylindrical shape along the longitudinal axis direction N. The heater  51  is arranged on the inside of the rigidity variable member  60  in a radial direction R and configured to heat the rigidity variable member  60 . 
     In addition, the heater  51  is constituted of a heating member which is pliable and has a small diameter, for example, a coil heater, in order to follow the pliability of the flexible tube portion  2   k . 
     The tube  52  is formed in an elongated and cylindrical shape along the longitudinal axis direction N, and arranged on an inside of the heater  51  in the radial direction R. 
     In addition, the tube  52  is an insulator and made of a material having a heat conductivity lower than a heat conductivity of the filler  30 , for example, a material including polyimide (heat conductivity of which is 0.3 W/m·K). Note that the material constituting the tube  52  is not limited to polyimide as long as the material is a resin material having a heat conductivity lower than that of the filler  30 . 
     The filler  30  is filled into a gap S formed between the heater  51  and the rigidity variable member  60  in the radial direction R. The gap S is created unavoidably in consideration of assemblability of the rigidity variable apparatus  100 . 
     In addition, the filler  30  is preferably made of a non-conductive material in order to ensure insulation to the heater  51 . Furthermore, the filler  30  is preferably made of a material having a heat conductivity (high heat conductivity) higher than that of air. Specifically, the filler  30  includes a heat-dissipating silicon potting material (heat conductivity 1.6 W/m·K, for example) or a heat-dissipating silicon adhesive. 
     Note that the filler  30  may be gelatinous or cured. 
     The filler  30  fills the gap S instead of gas G having a low heat conductivity, to improve the heat transfer performance of the heater  51  in transferring the heat H to the rigidity variable member  60 . 
     If the gas G having the low heat conductivity is filled into the gap S as described in the above-described conventional example, the heat transfer performance from the heater  51  to the rigidity variable member  60  is decreased by the gas G. Therefore, the rigidity variable apparatus  100  is configured such that the filler  30  having a high heat conductivity is filled into the gap S. 
     Note that, if an object of the present invention is only to improve the heat transfer performance from the heater  51  to the rigidity variable member  60  by using the filler  30 , the rigidity variable apparatus  100 , as shown in  FIG.  3   , does not have to include the tube  52  on the inside of the heater  51  in the radial direction R. 
     If the gas G having a low heat conductivity (for example, the heat conductivity of air is about 0.02 W/m·K) is filled into the inner side than the heater  51  in the radial direction R, the heat transfer performance from the heater  51  to the gas G is decreased. Therefore, the heat H of the heater  51  should be able to be efficiently transferred to the rigidity variable member  60  through the filler  30 . 
     However, if the assemblability of the rigidity variable apparatus  100  is taken into consideration, the filler  30  having the high heat conductivity is filled also into the inner side than the heater  51  in the radial direction R, as shown in  FIG.  4   . In other words, it is very difficult to manufacture the rigidity variable apparatus  100  shown in  FIG.  3   . In this case, the heat H of the heater  51  is transferred also to the filler  30  filled into the inner side than the heater  51  in the radial direction R. 
     Therefore, in the present embodiment, the tube  52  is provided to prevent the filler  30  from entering the inner side than the heater  51  in the radial direction R. 
     Note that, since the tube  52  is made of the material having the low heat conductivity, as described above, the heat H of the heater  51  is hardly transferred to the tube  52 , which enables the heat H of the heater  51  to be efficiently transferred to the rigidity variable member  60  through the filler  30 . 
     Next, description will be made on a manufacturing method of the rigidity variable apparatus  100  according to the present embodiment, with reference to  FIG.  5    and  FIG.  6   . 
       FIG.  5    is a cross-sectional view showing a state where the filler is filled into the inside of the rigidity variable member in the radial direction.  FIG.  6    is a cross-sectional view showing a state where the heater unit is pushed into the inside of the rigidity variable member in  FIG.  5   . 
     As shown in  FIG.  5   , first, the filler  30  is filled into the inside of the rigidity variable member  60  in the radial direction R, through the first opening  60   h   1 . 
     Next, the heater unit  50 , the one end  50   i  of which in the longitudinal axis direction N is closed, is passed, from the one end side  50   i , through the first opening  60   h   1 , to be pushed along the longitudinal axis direction N into the inside of the rigidity variable member  60  in the radial direction R, as shown in  FIG.  6   . 
     After that, the filler  30  is filled into the gap S between the heater  51  and the rigidity variable member  60  in the radial direction R. Since the one end  50   i  of the heater unit  50  is closed, the filler  30  does not enter into the inside of the tube  52  and is filled only into the gap S, while being discharged from the first opening  60   h   1 . Finally, after the pushing-in of the heater unit  50  is completed, the first opening  60   h   1  is sealed by an adhesive or the like. As a result, the rigidity variable apparatus  100  shown in  FIG.  2    is manufactured. 
     Thus, in the present embodiment, the filler  30  having the high heat conductivity is filled into the gap S between the heater  51  and the rigidity variable member  60  in the radial direction R. 
     In addition, the tube  52  having the heat conductivity lower than that of the filler  30  is provided on the inside of the heater  51  in the radial direction R. 
     With such a configuration, the tube  52  can prevent the state as shown in  FIG.  4    in which the filler  30  having the high heat conductivity is filled into the inner side than the heater  51  in the radial direction R. In addition, the tube  52  can effectively prevent the heat H of the heater  51  from being transferred to the inner side than the heater  51  in the radial direction R. 
     Thus, the heat H of the heater  51  is efficiently transferred to the rigidity variable member  60  through the filler  30  having the high heat conductivity. As a result, the rigidity variable member  60  can be hardened quickly. In other words, when the rigidity variable apparatus  100  is provided in the flexible tube portion  2   k , a desired part of the flexible tube portion  2   k  can be hardened quickly. 
      As described above, it is possible to provide the rigidity variable apparatus  100  having the configuration for enabling the hardening speed of the rigidity variable member  60  to be increased by improving the heat transfer performance from the heater  51  to the rigidity variable member  60 , and also provide the endoscope  1  including the rigidity variable apparatus  100 , and the manufacturing method of the rigidity variable apparatus  100 . 
     Second Embodiment 
       FIG.  7    is a cross-sectional view of a rigidity variable apparatus according to the present embodiment. 
     Configurations of the rigidity variable apparatus and an endoscope according to the second embodiment are different from those of the rigidity variable apparatus and the endoscope according to the first embodiment shown in  FIGS.  1  and  2   , in that a filler is filled also into an inside of the tube. 
     Therefore, only the different point will be described, and the same components as those in the first embodiment are attached with the same reference signs and descriptions thereof will be omitted. 
     As shown in  FIG.  7   , a rigidity variable apparatus  200  according to the present embodiment is configured such that the filler  30  is filled also into the inside of the tube  52  in the radial direction R. 
     Note that, even if the filler  30  having the high heat conductivity is filled into the inside of the tube  52  in the radial direction R, the tube  52  prevents the heat H of the heater  51  from being transferred to the filler  30  arranged on the inside of the tube  52  in the radial direction R. 
      Other configurations of the rigidity variable apparatus  200  are the same as those of the rigidity variable apparatus  100  in the first embodiment. 
     Next, description will be made on a manufacturing method of the rigidity variable apparatus  200  according to the present embodiment, with reference to  FIG.  5    and  FIG.  8   . 
       FIG.  8    is a cross-sectional view showing a state where the heater unit in  FIG.  7    is pushed into the inside of the rigidity variable member in  FIG.  5   . 
     As shown in  FIG.  5   , first, the filler  30  is filled into the inside of the rigidity variable member  60  in the radial direction R, through the first opening  60   h   1 . 
     Next, the heater unit  50 , which includes a second opening  50   h   2  at one end  50   i  in the longitudinal axis direction N and a third opening  50   h   3  at another end  50   t  in the longitudinal axis direction N, is passed, from the one end  50   i  side, that is, the second opening  50   h   2  side, through the first opening  60   h   1 , to be pushed into the inside of the rigidity variable member  60 , as shown in  FIG.  6   . 
     After that, the filler  30  enters the inside of the tube  52  through the second opening  50   h   2 , to be discharged from the third opening as well as from the first opening  60   h   1 . Furthermore, the filler  30  is filled into the gap S between the heater  51  and the rigidity variable member  60  in the radial direction R as well as into the inside of the tube  52  in the radial direction R. 
     Finally, after the pushing-in of the heater unit  50  is completed, the first opening  60   h   1  is sealed by an adhesive or the like. As a result, the rigidity variable apparatus  200  shown in  FIG.  7    is manufactured. 
      With also such a configuration, the same effects as those in the above-described first embodiment can be obtained. In addition, in the case where the gap S is extremely small in the radial direction R or in the case where the viscosity of the filler  30  is high, for example, in the configuration of the rigidity variable apparatus  100  in the first embodiment, it is very difficult to fill the filler  30  only into the gap S by the pushing-in of the heater unit  50 . 
     Specifically, it is very difficult to push the heater unit  50  into the inside of the rigidity variable member  60  while allowing the filler  30  to be discharged from the first opening  60   h   1 , as shown in  FIG.  6   . 
     However, according to the configuration and the manufacturing method of the rigidity variable apparatus  200  according to the present embodiment, when the heater unit  50  is pushed into the inside of the rigidity variable member  60 , while allowing the filler  30  to be discharged from the first opening  60   h   1 , as shown in  FIG.  8   , the filler  30  enters also the inside of the tube  52  through the second opening  50   h   2 , to be discharged from the third opening  50   h   3 . With such a configuration, it is easy to push the heater unit  50  into the rigidity variable member  60 . Therefore, the rigidity variable apparatus  200  can be surely manufactured. 
     Description will be made below on a modification, with reference to  FIG.  9    and  FIG.  10   .  FIG.  9    is a cross-sectional view showing a state where conductive wires are extended respectively from one end and another end of the heater in the rigidity variable apparatus in  FIG.  2   .  FIG.  10    is a cross-sectional view showing a state where conductive wires are extended respectively from one end and another end of the heater in the rigidity variable apparatus in  FIG.  7   . 
     In the above-described first and second embodiments, the heater  51  is required to be energized in order to generate the heat H from the heater  51 . 
      When the heater  51  is configured of a coil heater, the heater  51  is configured to generate heat by a current flowing between one end  51   a  and another end  51   b  of a wound heating wire that configures the coil heater. 
     Usually, a first conductive wire  41  is extended from the one end  51   a , and a second conductive wire  42  is extended from the other end  51   b . Note that the first conductive wire  41  and the second conductive wire  42  are each connected to a power source, not shown. In addition, both the first conductive wire  41  and the second conductive wire  42  configure the heating wire. 
     However, if the gap S is small in the radial direction R, there is a possibility that the second conductive wire  42  cannot be passed through the gap S. 
     Therefore, as shown in  FIG.  9    and  FIG.  10   , in rigidity variable apparatuses  100 ′ and  200 ′, the second conductive wire  42  may be arranged so as to pass through the inside of the tube  52  in the radial direction R. In this case, there is no need for passing the second conductive wire  42  through the gap S. As a result, it is possible to reduce the diameters of the rigidity variable apparatuses  100 ′ and  200 ′ in the radial direction R. 
     Note that the heater  51  usually has a configuration in which the outer circumference of the heating wire is covered with an insulation coating film. If the insulation coating film is broken, the heating wire is likely to make a short circuit to the second conductive wire  42  passing through the inside of the tube  52  in the radial direction R. However, as described above, the tube  52  is configured of an insulator, to thereby prevent the short circuit. 
     In other words, the tube  52  may have a function of preventing a short circuit between the heating wire and the second conductive wire  42  in the heater  51 . 
      Note that other effects are the same as those in the above-described first and second embodiments. 
     In addition, in the above-described first and second embodiments, the endoscope has been described by taking a colonoscope for medical use as an example. However, the present invention is applicable not only to the colonoscope, but also to other medical endoscopes and industrial endoscopes. 
     Furthermore, the rigidity variable apparatuses  100 ,  200 ,  100 ′, and  200 ′ according to the first and second embodiments may be provided in an insertion portion of a treatment instrument. 
     Furthermore, the present invention is not limited to the above-described embodiments, but can be changed appropriately within a range not departing from the gist or the concept of the invention that can be read from claims, throughout the specification, and the drawings.