Patent Publication Number: US-2012046523-A1

Title: Self propelling device

Description:
FIELD OF THE INVENTION 
     This present invention relates to a self propelling device for propelling an insert section of an endoscope in a body. 
     BACKGROUND OF THE INVENTION 
     An endoscope is provided with an insert section inserted into a body and an operation unit for operating the insert section. The insert section is sectioned into a distal portion, a bending portion and flexible portion. The distal portion and the bending portion are located at a front end side of the insert section. For example, an imaging capturing window for importing a target image is located on a front surface of the distal portion. The bending portion bends by operation of the operation unit to orient the distal portion toward a desired direction. The flexible portion has a length approximately 1 m to 2 m depending on the intended purpose of the endoscope. 
     In a colonoscope, the insert section is inserted into a large intestine from an anus. In the large intestine, since a sigmoid colon and a transverse colon relatively freely move in the body, it is difficult to advance the insert section deeply in the sigmoid colon or transverse colon, and much experience of manipulation of the endoscope is required. If a doctor is insufficiently skilled in the manipulation, physical load to the body of a patient will be very large. In view of such a problem, in order to assist the insertion, a self propelling device which propels the insert section in a body, for example, in a body cavity has been developed in recent years. 
     JP-A 2009-195321 discloses a self propelling device for inserting the insert section into a deep part in the large intestine, for example, back of a SD junction that is a boundary between the sigmoid colon and transverse colon. The self propelling device is provided with an extensible unit attached to a front end side of the inserter, and a balloon that is attached to a rear end of the extensible unit. While the balloon swells and contacts an intestine wall at the front of the SD junction, the extensible unit forwardly extends and the front end side of the insert section goes over the SD junction to advance deeply. Thereby, the insert section can be inserted into the back of the SD junction. 
     The self-propelling device disclosed in U.S. 2006/0089533 (corresponding to JP-A 2009-513250) is provided with an internal cylinder attached to the front end side of the inserter, and an external cylinder positioned outside of the internal cylinder, and a rotating body. The rotating body is wound between an inner periphery and an outer periphery of the external cylinder. The rotating body is supported by the external cylinder so as to rotate along an axial direction. The insert section can be inserted into the deep part of the large intestine by rotation of the rotating body in a manner that the rotating body contacts the intestine wall of the large intestine. 
     The self propelling device disclosed in the JP-A 2009-195321 is constituted of the extensible unit and the balloon, so that the self propelling device is formed long in an axial direction of the insert section. Thereby, the entire of the bending portion is covered with the self propelling device, in addition to the part of the distal portion and the part of the flexible portion. Therefore, there is a possibility that the bending operation, for example, bending of the bending portion at 180° is blocked by the self propelling device. 
     Also in the self propelling device disclosed in the WO 2007/050370, the internal cylinder and the external cylinder are formed long in the axial direction of the insert section, so that the entire of the bending portion is covered with the self propelling device. Therefore, problems arise in that the bending operation of the bending portion is blocked and the flexibility of the flexible portion is partly lost due to the self propelling device. As a result, the insert technique becomes more difficult. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a self propelling device for allowing smooth bending operation of a front end side of an insert section. 
     In order to achieve the above object, a self propelling device of the present invention has an internal cylinder, an external cylinder, a rotating body, a driver and a support member. The self propelling device is attached to a bendable front end side of an insert section of an endoscope and propels the front end side in a body. The internal cylinder has an insertion hole into which the front end side is inserted with a predetermined space. The external cylinder is disposed outside of the internal cylinder. The rotating body is wound to surround the outer periphery and inner periphery of the external cylinder. The driver rotates the rotating body along the axis direction of the external cylinder. The support member is provided between an inner periphery of the internal cylinder and an outer periphery of the front end side, and movably supports the front end side in an at least radial direction in the insertion hole. The driver rotates the rotating body to propel the front end side in the body. 
     A first end of the support member is preferably fixed to the inner periphery of the internal cylinder, and a second end of the support member is detachably fit onto the outer periphery of the front end side, and the first end and the second end are separated in the axis direction. Moreover, the support member is preferably a coil spring formed in a circular truncated cone shape, and the first end is positioned at a bottom having large diameter and the second end is positioned at a top having small diameter. Furthermore, the second end is preferably fit onto an outer periphery of a bending portion that is bendable and provided at the front end side. Still furthermore, the internal cylinder and the external cylinder are preferably formed in skirt shape gradually spreading toward the rear end side of the insert section. 
     According to the present inversion, since the front end of the insert section is movably supported in an at least radial direction in the insert section, it is possible to prevent the self propelling device from blocking bending operation of the front end when the insert section is bended. Thereby, the bending operation of the front end side can be smoothly carried out. 
     Moreover, one end of the support member and the other end thereof are separated along an axis direction of the internal cylinder, so that the front end side is easy to move in the radial direction in the insertion hole when the front end side is bended. Therefore, the front end side can be easily bended in the insertion hole. As a result, further smooth bending operation of the front end side can be achieved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above objects and advantages of the present invention will become more apparent from the following detailed description when read in connection with the accompanying drawings, in which: 
         FIG. 1  is a schematic diagram showing an endoscope system; 
         FIG. 2  is a sectional view illustrating a manner that a self propelling device is attached to an insert section of an electronic endoscope according to a first embodiment of the present invention; 
         FIG. 3  is an explanatory view illustrating a size relation between the self propelling device and the insert section; 
         FIG. 4  is a sectional view illustrating an example that a coil spring is reversely disposed in a front-back direction; and 
         FIG. 5  is a sectional view illustrating a self propelling device according to a second embodiment. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Shown in  FIG. 1 , an endoscope system  2  includes an electronic endoscope  10  and a self propelling device  11 . The electronic endoscope  10  includes a handling section  12  and an insert section  13  that is connected to the handling section  12  and inserted into a large intestine in a body. A universal code  14  is connected to the handling section  12 . Connecters (not shown) for respectively connecting to a light source device (not shown) and a processor (not shown) are provided at a front end of the universal code  14 . 
     The handling section  12  is provided with an angle knob  15 , an air/water feed button  16  and a suction button  17  and so on. Moreover, the handling section  12  is provided with a forceps channel  18  into which a medical instruments such as forceps and an electrosurgical knife are inserted. 
     The insert section  13  includes a flexible portion  19  having flexibility, a bending portion  20  that is freely bendable and a distal portion  21  in a sequence from the control handle  12 . The bending portion  20  and the distal portion  21  constitute a front end side of the insert section. 
     The flexible portion  19  has a length, for example, 1.6 m for reach of the distal portion  21  to an object of interest in the large intestine. The bending portion  20  has a length, for example 10 cm to 13 cm, and bends up and down or right and left in response to operation of the angle knob  15 . Thus, the distal portion  21  can be oriented in a desired direction. 
     The distal portion  21  has a length about 15 mm, and includes an image capturing window  30  (see  FIG. 2 ) for importing a target image in the large intestine. Objective optical system and image pickup device such as CCD or CMOS image sensors for capturing image of the target are provided at the back of the image capturing window  30 . The image pickup device is connected to the processor by a signal cable that is accommodated in the insert section  13 , the handling section  12  and the universal code  14 . The processor executes image processing of various functions to the image signal obtained from the image pickup device through the signal cable to generate video signal and outputs the data on a monitor (not shown) connected through the cable. Then, an observation image of the target is displayed on the monitor. 
     Moreover, the distal portion  21  is provided with an illumination window  31 , an air/water feed nozzle  32  and a forceps outlet port  33  and so on (see  FIG. 2 ). The illumination window  31  illuminates illumination light that is led from the light source device through light fiber to the internal body part. The air/water feed nozzle  32  jets air or water supplied from air/water feed device (not shown) toward the image capturing window  30  when the air/water feed button  16  is pressed. The forceps outlet port  33  is an outlet of the front end of the medical instrument that is inserted through the insert section  13  from the forceps channel  18 . 
     The self propelling device  11  is attached to the front end side of the insert section  13 , and carries the insert section  13  forward and backward in the large intestine. The self propelling device  11  is driven by a drive source  22 . The drive source  22  generates rotating torque for driving the self propelling device  11 . The rotating torque is transmitted to the self propelling device  11  through a rotating torque transmission member  55  (see  FIG. 2 ) connected to the drive source  22 . 
     The rotating torque transmission member  55  is inserted through a protective sheath  36  formed from such as fluorine resin. The protective sheath  36  is supported by plural support rings  37  fixed onto outer periphery of the insert section  13 . Therefore, the rotating torque transmission member  55  is supported along an axial direction of the insert section  13 . A torque wire or torque coil is used as the rotating torque transmission member  55 . 
     The drive source  22  is controlled by a controller (not shown). An operation unit (not shown) is attached to the controller. The operation unit includes a button for inputting command for moving forward, moving backward and stopping the self propelling device  11 , and a speed change button for changing a moving speed. Note that it may be possible that a program corresponding to an observation object is prepared in advance, and the drive source  22  is driven according to the program to automatically actuate the self propelling device  11 . 
     In  FIG. 2 , the self propelling device  11  includes a rotating body (rotor or toroid)  40 , a main body  41  that is almost cylinder shape and a coil spring  42  for attaching the main body  41  to the insert section  13 . The main body  41  includes an external cylinder  43  and an internal cylinder  44  that is placed inside of the external cylinder  43 . 
     The rotating body  40  is wound between the outer periphery and inner periphery of the external cylinder  43  so as to wrap the entire of the external cylinder  43 , and rotatably supported by the external cylinder  43 . The rotating body  40  is formed from a material having flexibility, in particular, a biocompatible plastic material, such as polyvinyl chloride, polyamide resin, fluorocarbon resin and the like. The rotating body  40  is a hollow structure having an outer surface  40   a  and an inner surface  40   b.  The inner part of the rotating body  40  is filled with anyone of fluid such as gas and liquid, or combination thereof. 
     The rotating body  40  rotates along an axial direction of the internal cylinder  44  in a manner that the outer surface  40   a  contacts the inner wall of the large intestine, shown with an allow line. Thereby, the rotating body  40  generates propulsion force for carrying the insert section  13  forward and backward along an insert direction Ai. 
     For example, when the insert section  13  is carried forward in the insert direction Ai, the rotating body  40  that contacts inner wall of the large intestine moves in a pulling direction reverse to the insert direction Ai, and turns at 180° at the rear end of the external cylinder  43  to be folded inside of the external cylinder  43 . After the rotating body  40  moves in the insert direction Ai in the inside of the external cylinder  43 , the rotating body  40  turns at 180° at the front end of the external cylinder  43  to be folded outside of the external cylinder  43 . While the outside of The rotating body  40  moves along the pulling direction, the inside of the rotating body  40  moves along the insert direction Ai to carry the insert section  13  forward. On the other hand, when the insert section  13  is carried backward in the pulling direction, the outside of the rotating body  40  rotates so as to move the outside thereof along the insert direction Ai and move the inside thereof in the purring direction. 
     The external cylinder  43  is positioned in a space  45  surrounded by the rotating body  40  to support the rotating body  40 . The internal cylinder  44  is disposed between the insert section  13  and the rotating body  40 . The internal cylinder  44  has an insertion hole  44   a  through which the bending portion  20  and the distal portion  21  (hereinafter referred to as the bending portion  20  et al.) are inserted. The inner diameter of the insertion hole  44   a  is sufficiently larger than diameter of the bending portion  20  et al. Thereby, a space  46  is formed in the insertion hole  44   a  for smooth bending of the bending portion  20 . 
     The coil spring  42  is formed in truncated cone shape, in which one end is positioned at a bottom and the other end is positioned at a top. A large loop (annular part)  42   a  having large diameter is located at the bottom and a small loop (annular part)  42   b  having small diameter is located at the top. The whole circumference of the large loop  42   a  is fixed onto the inner periphery of the internal cylinder  44  forming the insertion hole  44   a.  The whole circumference of the small loop  42   b  detachably engages with the outer periphery  20   a  of the bending portion  20 . Thereby, the bending portion  20  et al. are supported in the air in the insertion hole  44   a.  The front end side is movable and rotatable in an axis direction relative to the self propelling device  11  in the range of elastic deformation of the coil spring  42 . 
     It is noted that position for fixing the large loop  42   a  to the inner periphery of the internal cylinder  44  and the position for fixing the small loop  42   b  to the outer periphery  20   a  are separated each other in an axis direction of the internal cylinder  44 . This allows easy bending of the bending portion  20  upon bending the bending portion  20 , compared to the situation the both fixing positions are not separated. 
     Driven rollers  47  to  50  are rotatably attached to the periphery of the external cylinder  43  along the insert direction Ai. The driven rollers  47  to  50  have totally three sets, and provided at intervals of 120° in a circumferential direction of the external cylinder  43 . Each of the driven rollers  47  to  50  contacts the inner periphery  40   b  and rotates corresponding to rotation of the rotating body  40 . 
     Drive rollers  51  and  52  are rotatably attached to the periphery of the inner cylinder  44  along the insert direction Ai. The drive rollers  51  and  52  have totally three sets, and provided at intervals of 120° in a circumferential direction of the internal cylinder  44 . The drive rollers  51  and  52  contact the external cylinder  40   a.    
     The drive roller  51  locates between the driven rollers  47  and  48  and clamps the rotating body  40  between the driven rollers  47  and  48 . Moreover, the drive roller  52  locates between the driven rollers  49  and  50  and clamps the rotating body  40  at the position between the driven rollers  49  and  50 . The drive rollers  51  and  52  are rotated by a transmission gear tube  53  to rotate the rotating body  40 . 
     The internal cylinder  44  is a double cylinder having an inner cylinder  57  and an outer cylinder  59  that is placed outside of the inner cylinder  57 . The inner cylinder  57  and the outer cylinder  59  are uniformed through a front end  58  formed in a doughnut shape. A space for disposing the transmission gear tube  53  is provided between the inner cylinder  57  and the outer cylinder  59 . 
     The inner cylinder  57  has inner diameter larger than the outer diameter of the insert section  13  for sufficiently obtaining the space  46 . The drive rollers  51  and  52  are rotatably attached to the outer cylinder  59 . 
     The transmission gear tube  53  is fit onto the outer periphery of the inner cylinder  57 . Teeth  53   a  for engaging with the drive rollers  51  and  52  are formed on the outer periphery of the transmission gear tube  53 . It is noted that the teeth  53   a  are formed at two positions corresponding to the drive rollers  51  and  52 , but they may be continuously formed. The teeth  53   a  are worms, so that and the worm wheels are used for the drive rollers  51  and  52 . 
     A gear  54  having a number of teeth in its circumferential direction is formed at the rear end of the outer periphery of the transmission gear tube  53 . A pinion  56  provided at a front end of the rotation torque transmission member  55  engages with the gear  54 . The pinion  56  is rotated by the rotation torque transmission member  55  and the rotation is transmitted to the transmission gear tube  53  via the gear  54 . 
     It is noted the gear  54  is formed long in the insert direction Ai so as not to release engagement of the gear  54  and the pinion  56  even when the main body  41  moves toward the axis direction of the insert section  13 . The rotation torque transmission member  55  and the protective sheath  36  are slidably supported to the support ring  37 . 
     The transmission gear tube  53  is rotated around the central axis of the internal cylinder  44  with driving force from the pinion  56 . Thereby, the drive rollers  51  and  52  are rotated, and the rotating body  40  is rotated by the rotation of the drive rollers  51  and  52 . 
     Shown in  FIG. 3 , L 0 , L 1  and L 2  respectively represent lengths of the main body  41 , the distal end  21  and bending portion  20 . L 3  represents the inner diameter of the bending portion  20  bended at 180° and D 0  represents the outer diameter of the insert section  13 . In this case, the self propelling device  11  and the insert section  13  are formed so as to satisfy the following formula 1 and formula 2; 
         L 0≦ L 1+ L 3   [formula 1]
 
         L 3= L 2/π− D 0/2   [formula 2]
 
     Moreover, P 1  represents a position where the bending portion  20  contacts an edge of the insertion hole  44   a  when the bending portion  20  is bended at 180°, and the P 2  represents a boundary between the distal portions  21  and the bending portion  20 , and Cs represents a center of the bending portion  20 . Then, θ represents an angle intersecting a line joining P 1  and Cs, and a line joining P 2  and Cs. Moreover, D 1  represents an inner diameter of the insertion hole  44   a  and D 2  represents size of the space  46 . In this case, the self propelling device  11  and the insert section  13  are formed so as to satisfy the following formula 3 and formula 4; 
         D 2= D 1− D 0= L 3(1−cos θ)   [formula 3]
 
       θ≈sin −1 {( L 0− L 1)/ L 3}  [formula 4]
 
     To satisfy the following formulas 1 to 4 is a condition for allowing the bending portion  20  to bend at 180°. If the above condition is satisfied, there is no possibility that bending operation of the bending portion  20  is blocked by the self propelling device  11 . 
     Here, the larger the D 2  that is a size of the  46 , the easier the bending operation of the bending portion  20 . However, there is a case where DO that is outer diameter of the insert section  13  in formula 3 can not be small because of the large size of D 2 . In this case, it is necessary to enlarge the size of D 1  that is inner diameter of the insertion hole  44   a,  which makes difficult to insert the insert section  13  with the self propelling device  11  into the large intestine since the size of the self propelling device  11  becomes large. Therefore, the D 2  that is a size of the space  46  is determined considering D 0  that is outer diameter of the insert section  13  and the size of the self propelling device  11 . 
     Next, operation of the endoscope system  2  having the above-mentioned constitution is explained. First, the support rings  37  are respectively attached to the predetermined plural positions on the insert section  13 . Next, the rotation torque transmission member  55  is inserted through the holes of the support rings  37  via the protective sheath  36 . Then, the self propelling device  11  is attached to the bending portion  20  via the coil spring  42 . 
     The large loop  42   a  is fixed to the inner periphery of the internal cylinder  44  in advance. After the distal portion  21  is inserted through the insertion hole  44   a,  the small loop  42   b  is fit onto the outer periphery of the bending portion  20 . In particular, the distal portion  21  is inserted in the small loop  42   b  in a manner that the diameter of the small loop  42   b  is enlarged against the elastic deformation thereof. When the small loop  42   b  reaches the predetermined position of the bending portion  20  after passing through the distal portion  21 , force applied to the small loop  42   b  is released. Thereby, the small loop  42   b  is fixed so as to fasten the predetermined position of the bending portion  20 . Here, the attachment of the self propelling device  11  is completed. 
     After attachment of the self propelling device  11 , the processor, light source unit, control device are turned on, then the patients&#39; information are entered in an electronic medical chart server from the predetermined terminal. Next, the insert section  13  with the self propelling device  11  is inserted into the large intestine of the patient. 
     When the distal portion  21  is advanced front of, for example, the sigmoid colon of the large intestine, the operation unit is operated to turn on electric source of the drive source  22 . Then, command for advancing forward is input by button operation of the operation unit. The rotation torque transmission member  55  is rotated in the predetermined direction by the drive source  22 , and the transmission gear tube  53  is rotated by rotation of the pinion  56  corresponding to the rotation of the rotation torque transmission member  55 . 
     Rotation of the transmission gear tube  53  is transmitted to the drive rollers  51  and  52 , and the drive rollers  51  and  52  rotate the rotating body  40 . The rotating body  40  is rotated in a manner to contact the inner wall of the large intestine, to generate driving power in the insert direction Ai. The self propelling device  11  hauls the intestine wall of sigmoid colon with driving power from the rotating body  40  to carry the front end of the insert section  13  forward along the intestine wall of sigmoid colon. 
     When the command for speed change is input by button operation of the operation unit, the rotation speed of the rotation torque transmission member  55  is changed through the drive source  22 . Therefore, moving speed of the self propelling device  11  is changed. Moreover, when the command for carrying backward is input by button operation of the operation unit, the rotation torque transmission member  55  is reversely rotated through the drive source  22  and the front end side of the insert section  13  is carried backward. Furthermore, when the stop command is input through button operation of the operation unit, the drive source  22  stops and the self propelling device  11  also stops. Through the appropriate operation described above, the front end side of the insert section  13  can be carried to the desired position such as back of the sigmoid colon. 
     The operator operates the angle knob  15  to bend the bending portion  20  and orients the distal portion  21  in a desired direction. Shown in  FIG. 3 , the space  46  is sufficiently obtained. When the bending portion  20  bends, the bending portion  20  et al. are easy to move in the insertion hole  44   a  in its radial direction since the fixing position of the large loop  42   a  and the small loop  42   b  are separate each other in an axis direction of the internal cylinder  44 . Therefore, D 2  that is size of the  46  can be maximally obtained. This allows easy bend of the bending portion  20  in the insertion hole  44   a.  Consequently, bending operation of the bending portion  20  is not block by the self propelling device  11 , so that the bending portion  20  can be bended smoothly in a similar manner where the self propelling device  11  is not attached. 
     Shown in  FIG. 4 , it may be possible that the coil spring  42  is reversely disposed in a front-back direction. In particular, the small loop  42   b  is fixed on the outer periphery of the distal portion  21 , and the large loop  42   a  is fixed on the inner periphery of the internal cylinder  44 . In this case, it is preferable that whole circumferences of the large loop  42   a  and the small loop  42   b  may be respectively fixed on the inner periphery of the internal cylinder  44  and the outer periphery of the distal portion  21 . 
     Next, a self propelling device  60  in the second embodiment of the present invention will be described with reference to the  FIG. 5 . It is noted that the parts having the same structure and function as the above first embodiment have the same reference numerals, and their description will not be repeated. 
     The self propelling device  60  includes a rotating body  61  and a main body  62 . Since the rotating body  61  is basically same as the rotating body  40  of the first embodiment, explanation thereof will not be repeated. The main body  62  includes an external cylinder  63  and an internal cylinder  64 . The external cylinder  63  is disposed in a space  65  inside of the rotating body  61 . The external cylinder  63  rotatably supports the rotating body  61  in a similar manner to the external cylinder  43  of the first embodiment. The internal cylinder  64  is disposed between the insert section  13  and an outer surface  61   a  of the rotating body  61 . 
     The external cylinder  63  has a cylinder  63   a  and a skirt  63   b.  The internal cylinder  64  has a cylinder  64   a  and a skirt  64   b.  The skirts  63   b  and  64   b  are respectively connected to the rear end of the cylinders  63   a  and  64   a.  The skirts  63   b  and  64   b  gradually spread toward the rear end of the insert section  13 . Moreover, the inner periphery of the skirts  63   b  and  64   b  are formed step-shape. Inner periphery of the skirts  63   b  and  64   b  forms a space  70  in the main body  62  for smoothly bending the bending portion  20 . 
     Driven rollers  72 ,  73  and  74  are rotatably attached to a peripheral surface of the external cylinder  63  along the insertion direction Ai. Each of the driven rollers  72  to  74  has totally three sets, and provided at intervals of 120° in a circumferential direction of the external cylinder  63 . The driven  72  is disposed at front end of the cylinder  63   a.  The driven roller  73  is disposed at rear end of the cylinder  63   a.  The driven roller  74  is disposed at rear end of the skirt  63   b.  Each of the driven rollers  72  to  74  contacts an inner surface  61   b  of the rotating body  61  and rotates according to rotation of the rotating body  61 . 
     A drive roller  75  and a driven roller  76  are rotatably attached to a peripheral surface of the internal cylinder  64  along the insertion direction Ai. Each of the drive roller  75  and the driven roller  76  has totally three sets, and provided at intervals of 120° in a circumferential direction of the internal cylinder  64  and contacts an outer surface  61   a.  The drive roller  75  is disposed in the middle of the cylinder  64   a.  The driven roller  76  is disposed at the rear end of the skirt  64   b.    
     The drive roller  75  locates between the driven rollers  72  and  73  and clamps the rotating body  61  between the driven rollers  72  and  73 . Moreover, the driven roller  76  clamps the rotating body  61  with the driven roller  74 . The drive roller  75  is rotated by a transmission gear tube  77  to rotate the rotating body  61 . The driven roller  76  rotates corresponding to the rotation of the rotating body  61 . 
     Since the transmission gear tube  77  is basically same as the transmission gear tube  53  of the first embodiment, explanation thereof will not be repeated. It is noted that the rotation torque transmission member  55  for rotating the transmission gear tube  77  and the pinion  56  are omitted in the drawings. 
     The cylinder  64   a  has an insertion hole  80  into which the bending portion  20  et al. are inserted. The inner diameter of the insertion hole  80  is sufficiently larger than the outer diameter of the bending portion  20 . Therefore, a space  81  which has sufficient space not to block the bend of the bending portion  20  is provided between the bending portion  20  et al. and the inner periphery of the cylinder  64   a  forming the insertion hole  80 . 
     The bending portion  20  et al. are supported in the air in the insertion hole  80  by the coil spring formed in truncated cone shape, in a similar manner to the first embodiment. The coil spring  82  has a large loop  82   a  and a small loop  82   b.  The large loop  82   a  is fixed to the inner periphery of the cylinder  64   a.  The small loop  82   b  is fixed to the outer periphery of the bending portion  20 . Consequently, bending operation of the bending portion  20  can be smoothly carried out in a similar manner to the first embodiment. 
     Further, in the self propelling device  60 , a space  70  formed by the skirt  64   b  is provided, in addition to the space  81  formed by the insertion hole  80 . Therefore, shown with a phantom line  13   a,  more smooth bending operation of the bending portion  20  can be carried out compared to the first embodiment. 
     It is noted that the location and the number of the driven roller and the drive roller are not limited to the above first and second embodiments and may be properly changeable. 
     In the embodiments described above, whole circumferences of the large and small loops of the coil spring are respectively fixed to the internal cylinder or the inner periphery of the internal cylinder, the outer periphery of the bending portion, but the present invention is not limited to this and several points of the large and small loops may be fixed to the inner periphery and the outer periphery. 
     In the above first embodiment, the large loop  42   a  is fixed to the front end side or rear end side of the main body  41 , and the small loop  42   b  is detachably fit to the middle portion of the bending portion  20  or the distal portion  21 , but the present invention is not limited to this and for example, the large loop  42   a  may be fixed to the middle portion of the main body  41  and the small loop  42   b  may be fixed to the middle portion or the rear end of the bending portion  20 . Moreover, it may be possible to change length of the coil spring  82  in the second embodiment and appropriately change positions of the large loop  82   a  and the small loop  82   b.    
     In the above embodiments, the toroid-shaped rotating body is used, but the shape of the rotating body is not limited to this, for example, an endless belt formed in band-shape may be used. 
     The colonoscope is used in the above embodiments, but the present invention can be applied to a gastroscope and so on. Further, the present invention is not limited for medical diagnosis use, but may be applied to a self propelling device attached to various endoscopes such as industrial endoscope or ultrasonic endoscope. 
     Various changes and modifications are possible in the present invention and may be understood to be within the present invention.