Endoscope insertion apparatus

1. An endoscope insertion apparatus for inserting an endoscope into a duct, the endoscope insertion apparatus comprising:

inner-side arm members that press a duct wall;

an inner-side insertion assisting section in which the inner-side arm members are uniformly arranged in a circumferential direction on a distal end side of an inner-side insertion assisting section body portion;

outer-side arm members that press the duct wall; and

an outer-side insertion assisting section mounted on an outer circumferential portion of the inner-side insertion assisting section, in which the outer-side arm members are uniformly arranged in a circumferential direction on a distal end side of an outer-side insertion assisting section body portion such that the inner-side arm members and the outer-side arm members are alternately arranged circumferentially around the outer-side insertion assisting section;

wherein the inner-side arm members can be changed between a reduced diameter state and an expanded diameter state in which the inner-side arm members press the duct wall, and the outer-side arm members can be changed between a reduced diameter state and an expanded diameter state in which the outer-side arm members press the duct wall, and

the outer-side arm members and the inner-side arm members move forward and rearward with respect to each other in an insertion direction such that the outer-side arm members and the inner-side arm members alternately change between:

a state in which the outer-side arm members in the expanded diameter state change to the reduced diameter state and the inner-side arm members in the reduced diameter state change to the expanded diameter state, to thereby change a front/rear relationship with respect to the insertion direction between the outer-side arm members and the inner-side arm members; and

a state in which the inner-side arm members in the expanded diameter state change to the reduced diameter state and the outer-side arm members in the reduced diameter state change to the expanded diameter state, to thereby change a front/rear relationship with respect to the insertion direction between the inner-side arm members and the outer-side arm members.

2. The endoscope insertion apparatus according to claim 1 , wherein:

in the inner-side insertion assisting section, a plurality of inner-side fixing sections are uniformly arranged in a circumferential direction, the inner-side fixing sections comprising the inner-side arm members each of which is changeable between the expanded diameter state and the reduced diameter state, with distal end portions of the inner-side arm members being pressed and fixed to the duct wall in the expanded diameter state; and

in the outer-side insertion assisting section, a plurality of outer-side fixing sections are uniformly arranged in a circumferential direction, the outer-side fixing sections comprising:

the outer-side arm members each of which is changeable between the expanded diameter state and the reduced diameter state, with distal end portions of the outer-side arm members being pressed and fixed to the duct wall in the expanded diameter state, and

slit portions that extend in a direction perpendicular to the circumferential direction and from which the inner-side arm members protrude when the outer-side insertion assisting section is mounted to the outer circumferential portion of the inner-side insertion assisting section are uniformly arranged in the circumferential direction between the outer-side fixing sections;

the endoscope insertion apparatus further comprising:

an insertion operation portion that causes the inner-side arm members and the outer-side arm members to perform the diameter-expanding operation or the diameter-reducing operation, and to change the relative positions between the inner-side insertion assisting section and the outer-side insertion assisting section to thereby change the front/rear relationship with respect to the insertion direction between the inner-side arm members and outer-side arm members.

3. The endoscope insertion apparatus according to claim 2 , further comprising:

an inner-side operation transmitting section that is connected to each of the inner-side arm members and that is capable of a pushing/pulling operation with respect to each of the inner-side arm members in the insertion direction; and

an outer-side operation transmitting section that is connected to each of the outer-side arm members and that is capable of a pushing/pulling operation with respect to each of the outer-side arm members in the insertion direction;

wherein each of the inner-side arm members changes position between the expanded diameter state and the reduced diameter state by rotating around a corresponding inner-side insertion assisting section pivot as a result of the pushing/pulling operation of the inner-side operation transmitting section, and

each of the outer-side arm members changes position between the expanded diameter state and the reduced diameter state by rotating around a corresponding outer-side insertion assisting section pivot as a result of the pushing/pulling operation of the outer-side operation transmitting section.

4. The endoscope insertion apparatus according to claim 3 ,

wherein the insertion operation portion comprises:

an inner-side operation portion that operates the inner-side operation transmitting section and to which is connected an inner-side guide pipe through which the inner-side operation transmitting section is inserted; and

an outer-side operation portion that operates the outer-side operation transmitting section and to which is connected an outer-side guide pipe through which the outer-side operation transmitting section is inserted;

wherein the inner-side insertion assisting section and the outer-side insertion assisting section can be moved with respect to the insertion direction.

5. The endoscope insertion apparatus according to claim 3 , wherein:

each of the inner-side arm members has an inner-side arm member cam groove that engages with a corresponding inner-side arm member cam pin that is moved by a pushing/pulling operation of the inner-side operation transmitting section, and is pivotally held by the corresponding inner-side insertion assisting section pivot; and

each of the outer-side arm members has an outer-side arm member cam groove that engages with a corresponding outer-side arm member cam pin that is moved by a pushing/pulling operation of the outer-side operation transmitting section, and is pivotally held by the corresponding outer-side insertion assisting section pivot.

6. The endoscope insertion apparatus according to claim 3 , wherein:

each of the inner-side fixing sections has an inner-side elastic fixing section that retains each of the inner-side arm members in the reduced diameter state; and

each of the outer-side fixing sections has an outer-side elastic fixing section that retains each of the outer-side arm members in the reduced diameter state,

the endoscope insertion apparatus further comprising:

an inner-side operation transmitting section that is connected to each of the inner-side arm members and that changes a position of each of the inner-side arm members to the expanded diameter state by compressing the inner-side elastic fixing section by means of a pushing/pulling operation in a direction of the axis of advancement and retraction; and

an outer-side operation transmitting section that is connected to each of the outer-side arm members and that changes a position of each of the outer-side arm members to the expanded diameter state by compressing the outer-side elastic fixing section by means of a pushing/pulling operation in a direction of the axis of advancement and retraction.

7. The endoscope insertion apparatus according to claim 3 , wherein:

each of the inner-side fixing sections has an inner-side inflation/deflation portion that is inflatable and deflatable and that retains each of the inner-side arm members in the expanded diameter state when inflated and retains each of the inner-side arm members in the reduced diameter state when deflated; and

each of the outer-side fixing sections has an outer-side inflation/deflation portion that is inflatable and deflatable and that retains each of the outer-side arm members in the expanded diameter state when inflated and retains each of the outer-side arm members in the reduced diameter state when deflated;

the endoscope insertion apparatus further comprising an inner-side supply and discharge section that supplies or discharges a fluid to or from the inner-side inflation/deflation portion, and an outer-side supply and discharge section that supplies or discharges a fluid to or from the outer-side inflation/deflation portion.

8. The endoscope insertion apparatus according to claim 3 , further comprising a cover section that is formed using a flexible resin film and that covers a portion of the inner-side arm members and the outer-side arm members while exposing the distal end portions of the inner-side arm members and the distal end portions of the outer-side arm members.

9. The endoscope insertion apparatus according to claim 1 , wherein:

in the inner-side insertion assisting section, inner-side arm members that press a duct wall by means of an elastic force in a condition in which an amount of friction in an insertion direction with respect to the duct wall of distal end portions of the inner-side arm members is less than an amount of friction in a withdrawal direction are uniformly arranged in a circumferential direction on the distal end side of the inner-side insertion assisting section body portion; and

in the outer-side insertion assisting section, outer-side arm members that press the duct wall by means of an elastic force in a condition in which an amount of friction in an insertion direction with respect to the duct wall of distal end portions of the outer-side arm members is less than an amount of friction in a withdrawal direction are uniformly arranged in a circumferential direction on the distal end side of the outer-side insertion assisting section body portion, and the outer-side insertion assisting section is mounted to the outer circumferential portion of the inner-side insertion assisting section such that the inner-side arm members and the outer-side arm members are alternately arranged in a circumferential direction, and advances and retracts on a same axis as the inner-side insertion assisting section.

10. The endoscope insertion apparatus according to claim 9 , wherein the inner-side arm members and the outer-side arm members are elastic bodies.

11. The endoscope insertion apparatus according to claim 10 , wherein the inner-side arm members are longer than the outer-side arm members in an axial direction along which the outer-side insertion assisting section advances and retracts.

12. The endoscope insertion apparatus according to claim 9 , wherein the outer-side insertion assisting section has slit portions through which the inner-side arm members protrude at the distal end side of the outer-side insertion assisting section body portion.

13. The endoscope insertion apparatus according to claim 9 , further comprising a traction portion that draws the distal end portions of the inner-side arm members and the distal end portions of the outer-side arm members in a direction of a center of the axis of advancement and retraction, and releases a state in which the inner-side arm members and the outer-side arm members press the duct wall.