JPH07308286A - Mechanism for fixing treatment tool insert channel of endoscope - Google Patents

Abstract

PURPOSE:To surely fix a flexible tube by engaging a stopper part to be fixed to the treatment tool path side with a through hole formed on the flexible tube from the inner surface in a non-projecting state. CONSTITUTION:A flexible tube 15 is inserted in a treatment tool path, the path 16 is divided into a large-diameter path part 16a and a small-diameter path part 16b, and the tube 15 is inserted until it comes into contact with a stepped part between the parts to be fixed by an adhesive. Further, a circular through hole 15a is bored in a part of the tube that is inserted in the path 16, a pin insert hole 17 is bored in the peripheral drum part of a hard part 10a in the direction intersecting perpendicularly to its axial direction, and the hole 17 is opened to the interior of the path part 16a. A pin 18 is installed in the through hole 17, the shaft part 18b of the pin 18 is inserted in the through hole 15a in a close fitting state, and the tube 15 is fixed not to be deviate from the treatment tool path 16 by fitting of an adhesive, the pin 18 and the through hole 15a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a treatment instrument insertion channel which is provided in an insertion portion of an endoscope used for medical purposes and through which forceps and other treatment instruments are inserted.
In particular, the present invention relates to a treatment instrument insertion channel fixing mechanism of an endoscope for fixing the distal end portion of a flexible tube forming a treatment instrument insertion channel to a treatment instrument passage formed in a distal end hard portion of an insertion portion.

[0002]

2. Description of the Related Art An endoscope is provided with a treatment instrument insertion channel for inserting forceps and other treatment instruments. The treatment instrument insertion channel is usually provided from a treatment instrument introduction section provided in a main body operation section. It is for guiding the treatment instrument to the treatment instrument lead-out port formed in the distal end hard portion of the insertion portion. When the insertion part is a flexible flexible mirror that bends along the insertion path, the treatment instrument insertion channel mounted in the insertion part is also formed of a flexible tube. And
This flexible tube is connected at its distal end to a treatment instrument lead-out port having an opening at the distal end hard portion, and this connecting portion has conventionally been configured as shown in FIG. 11.

In the figure, reference numeral 1a denotes a distal end hard portion constituting the insertion portion 1, and a distal end hard portion 1a is provided with a treatment instrument passage 2 having a treatment instrument outlet port 2a on the distal end side in the axial direction thereof. Has been done. The proximal end side of the treatment instrument passage 2 has its hole diameter enlarged, and the metal connection pipe 3 is inserted into this enlarged diameter portion and fixed by an adhesive. A flexible tube 4 extends from a main body operating portion (not shown) in which the base end portion of the insertion portion 1 is continuously provided, and the distal end portion of the flexible tube 4 is fitted to the connecting pipe 3. And is fixed using an adhesive. Therefore, the flexible tube 4, the connecting pipe 3 and the treatment instrument passage 2 form a treatment instrument insertion channel, and the forceps and other treatment instruments are guided by the treatment instrument insertion channel to have a predetermined length from the treatment instrument outlet port 2a. By projecting, cells can be collected and the affected area can be treated.

By the way, in the insertion part 1, the distal end hard part 1a is continuously provided with an angle part 1b. As is well known, the angle part 1b is desired by pushing and pulling an angle operation wire. It can be bent in the direction of. When the angle portion 1b is bent at a large angle, the flexible tube 4 is also bent accordingly. However, since the connecting pipe 3 is formed of a hard member, the flexible tube 4 changes its shape from the curved shape to the linear shape at the fitting portion of the connecting tube 3. Then, the treatment tool is inserted into the flexible tube 4 not only when the angle portion 1b is straight but also when it is curved.

As shown in FIG. 12, when the treatment instrument 5 is inserted into the flexible tube 4 in a state where the flexible tube 4 is curved by an angle operation, the treatment instrument 5 is bent. Is guided so as to slide along the outer side of the inner surface, that is, the surface on the side having a smaller curvature. When reaching the fitting portion of the connecting pipe 3 of the flexible tube 4, the treatment instrument 5 moves into the connecting pipe 3, but at the fitting portion of the flexible tube 4 to the connecting pipe 3, a curved shape to a linear shape is formed. Since the shape of the connecting pipe 3 changes, the treatment tool 5 catches on the edge portion of the tip of the connecting pipe 3 and the transferability into the connecting pipe 3 deteriorates.

Further, since the flexible tube 4 needs to smoothly follow the bending of the entire insertion portion 1 or the angle portion 1b, it is necessary to have some flexibility, and for this reason, the flexible tube 4 is required. Is made of a resin material. Moreover, in order to smoothly insert the treatment tool inside,
It is made of slippery material. From the viewpoint of easiness of machining, strength, etc., the hard tip portion 1a is usually formed of a metal material. Therefore, if an adhesive is used, the connecting pipe 3 can be securely fixed to the treatment instrument passage 2, but It is difficult to sufficiently exert the fixing force by the adhesive between the metal material which is the material of No. 3 and the resin which constitutes the flexible tube 4, and easily peels off when a strong pulling force acts. There is a risk. For this reason, it is necessary to make the fitting length of the flexible tube 4 to the connecting pipe 3 as long as possible to obtain a wide bonding area. Since the connecting pipe 3 is a hard member, if the connecting pipe 3 is lengthened, the hard portion at the distal end portion of the endoscope 1 becomes longer, and the insertion operability when inserted into the patient's body deteriorates. In addition, there is a problem that the patient's pain is increased.

[0007]

In order to solve the above-mentioned problems, a step is generated in the insertion path of the treatment instrument by directly inserting the flexible tube into the treatment instrument passage having the treatment instrument outlet. It is also known to have a configuration that does not exist. However, the flexible tube cannot be arranged at the axial center position of the insertion part due to the arrangement relationship of other built-in objects,
It is provided at a position off the axis of the insertion portion. For this reason, when the angle portion is curved, a difference occurs in the curvature between the portion close to the axis and the portion distant from the axis of the flexible tube. Force of. As a result, if the insertion length of the flexible tube into the treatment instrument passage is short, the flexible tube may be separated from the treatment instrument passage.

From the above, in order to prevent the flexible tube from being separated from the treatment instrument passage, a threaded portion is formed on the outer surface of the flexible tube and the inner surface of the treatment instrument passage to form the flexible tube. A configuration is also known in which the device is inserted by being screwed into the treatment instrument passage and is fixed by using an adhesive. However, if the screw type is used,
There are drawbacks such as a complicated structure and difficulty in manufacturing.

The present invention has been made in view of the above points, and an object thereof is to securely fix a flexible tube even if the length of the hard portion at the tip of the insertion portion is minimized. It is possible to smoothly insert the treatment tool.

[0010]

In order to achieve the above-mentioned object, the present invention has a treatment instrument passage provided in a distal end hard portion in an insertion portion of an endoscope, and a tip thereof is connected to the treatment instrument passage. A flexible tube, which is a treatment instrument insertion channel for inserting a treatment instrument, wherein the flexible tube is inserted into the treatment instrument passage and connected / fixed with an adhesive, and the flexible tube 1 to a plurality of through-holes are formed in the insertion portion of the treatment instrument passage, and a stopper portion fixed to the treatment instrument passage side is engaged in the through-hole in a non-projecting state from the inner surface of the flexible tube. The feature is that it is configured to be.

[0011]

The flexible tube forming the treatment instrument insertion channel is inserted into the treatment instrument insertion passage of the hard tip portion and fixed to this insertion portion with an adhesive. In addition to this, the insertion portion is added to the adhesive to provide a stopper portion, and the stopper portion mechanically restricts the movement of the flexible tube in the axial direction. As a result, even when the flexible tube has a short insertion length into the treatment instrument insertion passage and the bonding area is small, when a strong pulling force is applied to the flexible tube by an angle operation or the like, it is There is no risk of falling out of the treatment instrument insertion passage. Further, even when the angle portion is curved, no step is formed on the inner surface of the entire treatment instrument insertion channel, so that the treatment instrument can be smoothly inserted,
The insertability of this treatment tool is improved.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, as a first embodiment of the present invention, FIG.
2 shows the appearance of the distal end surface of the insertion portion, FIG. 2 shows the cross section of the distal end portion, FIG. 3 shows the external appearance of the distal end portion of the flexible tube, and FIG. 4 is an enlarged view of the main portion of FIG. Show.

In the figure, reference numeral 10 denotes an insertion portion, and this insertion portion 10 has a hard tip portion 10a formed of a metal member, and a hard tip portion 10a is connected to an angle portion 10b. . As is well known, the angle portion 10b is formed by sequentially pivotally attaching a plurality of angle rings 11, and when the angle operation wire (not shown) is pushed and pulled, the tip hard portion 10a is directed in a desired direction. To be operated. The hard portion in the tip portion is a portion from the tip rigid portion 10a to the tip ring 11a directly connected to the tip rigid portion 10a, and the portion from the tip ring 11a to the angle ring 11 is pivotally attached. The part becomes a hard part.

A pair of illumination windows 12 and 12 and an observation window 13 are provided on the tip surface of the hard tip portion 10a, and illumination light is emitted from the illumination window 12 into the body cavity or the like.
The inside of the body cavity can be observed through the observation window 13.
Further, the insertion portion 10 is provided with a treatment instrument insertion channel 14.

The treatment instrument insertion channel 14 has a flexible tube 15, and the distal end portion of the flexible tube 15 is inserted into the treatment instrument passage 16 provided in the distal end hard portion 10a. The treatment instrument passage 16 is provided with a step at a portion close to the distal end surface, and due to this step, the large-diameter passage portion 16 on the proximal end side is provided.
a and a small diameter passage portion 16b on the tip side. The tip of the small-diameter passage portion 16b serves as a treatment instrument outlet 16c for guiding the treatment instrument to the outside. The flexible tube 15 is directly inserted into the treatment instrument passage 16,
The tip portion is in contact with the step portion. Large diameter passage portion 16a and small diameter passage portion 16 in the treatment instrument passage 16
The difference in diameter from b is substantially the same as or slightly smaller than the thickness of the flexible tube 15, which allows the flexible tube 15 to reach the treatment instrument outlet 16c through the small diameter passage portion 16b. There is substantially no step up to this point, and there is no step that rises at least on the front side in the lead-out direction of the treatment instrument. An adhesive is applied to the outer surface of the flexible tube 15, and the flexible tube 15 is fixed to the treatment instrument passage 16 by this adhesive.

Further, as shown in FIG. 3, the flexible tube 15 is provided with a circular through hole 15a at a portion of the distal end portion to be inserted into the treatment instrument passage 16. A pin insertion hole 17 is formed in the peripheral body portion of the distal end hard portion 10a in a direction orthogonal to the axial direction thereof, and the pin insertion hole 17 is opened in the large diameter passage portion 16a of the treatment instrument passage 16. There is. Then, a pin 18 as a stopper piece is attached to the pin insertion hole 17 and fixed by using a sealing material having an adhesive function. Pin 18 is head 18a
The pin insertion hole 17 includes a large diameter portion 17a for accommodating the head portion 18a of the pin 18 and a small diameter portion 17b for inserting the shaft portion 18b.
b penetrates the small diameter portion 17b and projects into the large diameter passage portion 16a of the treatment instrument passage 16. Moreover, as is clear from FIG. 4, the treatment instrument passage 16 in the shaft portion 18 b of the pin 18
The protruding length inward is substantially equal to the thickness of the flexible tube 15, and the outer diameter thereof is the through hole 15 of the flexible tube 15.
The diameter of the shaft portion 18b is substantially the same as the inner diameter of "a".

The pin 18 has a shaft portion 18b.
Is a screw rod, and the pin insertion hole 17 is a screw hole.
The pin 18 can be screwed.
Moreover, it is preferable that the tip end surface of the shaft portion 18a of the pin 18 has a concave curved surface shape along the inner surface of the flexible tube 15. However, a slight step is formed between the tip end surface of the pin 18 as long as it does not affect the insertability of the treatment tool. It does not matter if it occurs.

Further, the insertion portion 10 has an angle portion 10b.
From the middle to the middle position of the hard tip 10a,
An outer skin tube 19 is put on, and a tip end portion of the outer skin tube 19 is fixed by winding a bobbin 20 and applying an adhesive so that the inside becomes airtight. The pin 18 described above is attached to a portion surrounded by the outer skin tube 19.

In order to connect and fix the tip portion of the flexible tube 15 to the hard tip portion 10a, first, before the outer tube 19 is attached, the pin 18 is attached to the pin insertion hole 17 and the sealing material is attached. It is fixed by filling. In this state, an adhesive is applied to the outer surface of the distal end portion of the flexible tube 15 and the flexible tube 15 is inserted into the treatment instrument passage 16. At this time, as shown in FIG. 5, the portion of the distal end portion of the flexible tube 15 where the through hole 15a is formed is curved inward. As a result, the flexible tube 15 can be inserted into the treatment instrument passage 16 while avoiding the shaft portion 18b of the pin 18 projecting inward from the large diameter passage portion 15a of the treatment instrument passage 16. The distal end of the flexible tube 15 has a large diameter passage portion 16 a and a small diameter passage portion 16 in the treatment instrument passage 16.
Although it is brought into contact with the stepped portion between b and b, at this time, as shown by an imaginary line in FIG. 4, the portion where the through hole 15a is provided is in a state of being lifted from the large diameter passage portion 16a. Therefore, the raised portion is pressed against the treatment instrument passage 16 to restore the original state. This allows pin 18
The shaft portion 18b of the flexible tube 15 is inserted into the through hole 15a of the flexible tube 15 in a substantially tightly fitted state, and the entire flexible tube 15 is the inner surface of the large diameter passage portion 16a of the treatment instrument passage 16. Is adhered to and fixed by the action of the adhesive. When the flexible tube 15 is connected to the distal end hard portion 10a in this manner, the outer tube 19 is mounted, the spool 20 is applied, and the adhesive is applied on the wound tube 20 to cover the mounting portion of the pin 18. The inside of the insertion portion 10 is kept airtight.

As described above, the treatment instrument insertion channel 1
4 is assembled, the insertion portion 10 is inserted into the body cavity, the treatment instrument is inserted into the treatment instrument insertion channel 14, and the treatment instrument is projected from the treatment instrument outlet 16c to the outside.
A desired treatment such as cell collection or incision of an affected area can be performed. Here, since the flexible tube 15 forming the treatment instrument insertion channel 14 is directly inserted into the treatment instrument passage 16 in the distal end hard portion 10a without using a connecting pipe or the like, the angle portion 10b should be curved. However, since the curved portion on the inner surface of the flexible tube 15 does not have a step, the treatment tool can be inserted extremely smoothly. Further, there is a transition portion from the flexible tube 15 to the small diameter passage portion 16b of the treatment instrument passage 16 in the distal end hard portion 10a, but this portion is always kept in a straight line state, and the large diameter passage portion 16a and Small diameter passage 16
The height of the step from b is almost the same as the thickness of the flexible tube 15. Therefore, since there is substantially no step at this portion, the smoothness of the transition of the treatment instrument from the inside of the flexible tube 15 to the small diameter passage portion 16b is not impaired. The inner diameter of the flexible tube 15 and the small diameter passage portion 1
Although the step is eliminated by making the inner diameter of 6b substantially coincide with each other, there may be a step in which the inner diameter of the small diameter passage portion 16b is larger. The treatment instrument passage 16 of the treatment instrument passage 16 is composed of a large diameter passage portion 16a and a small diameter passage portion 16b. However, the treatment instrument passage 16 does not have a diameter corresponding to the large diameter passage portion 16a, and the flexible tube 15 has this diameter. You may comprise so that it may be inserted even to the treatment implement outlet in a treatment implement passage.

Since the flexible tube 15 is made of a resin material and the hard tip portion 10a is made of a metal material, a sufficient fixing force can be obtained only by fixing the both with an adhesive. When the flexible tube 15 cannot be exhibited and the angle portion 10b is curved and a strong tensile force is repeatedly applied to the flexible tube 15, the adhesive portion is peeled off and the flexible tube 15 is removed.
May deviate. However, the through hole 15a formed in the flexible tube 15 has a shaft portion 18 of the pin 18
Since the b is inserted so as to form a substantially tight fit, and the flexible tube 15 has a considerable thickness from the viewpoint of preventing kinks, the pin 18 is a through hole of the flexible tube 15. It engages with the end surface of 15a and functions as a stopper that restricts the axial movement of the flexible tube 15 and mechanically restricts the flexible tube 15 from deviating from the treatment instrument passage 16. . Therefore, even if the adhesive force of the flexible tube 15 is weak, the flexible tube 15 can be reliably fixed in the treatment instrument passage 16, and even if a strong pulling force acts, it does not deviate. .

Further, since it is not necessary to provide a member such as a connecting pipe which projects from the distal end hard portion 10a to the proximal end side in order to fix the flexible tube 15, the length of the distal end ring 11a is shortened. Thus, the length of the hard portion from the tip hard portion 10a to the pivotal attachment portion of the tip ring 11a to the angle ring 11 can be shortened. As a result, the insertion operability when inserting the insertion portion 10 into the body cavity is improved, and the pain of the patient can be reduced.

Further, the flexible tube 15 is formed with the through hole 15a, the pin hard hole 10a is provided with the pin insertion hole 17, and the pin 18 is inserted into the pin insertion hole 17. Can be firmly fixed,
The structure of the fixing mechanism of the flexible tube 15 is remarkably simplified.

By the way, if an excessive bending force is applied to the flexible tube 15, a kink may occur.
When the flexible tube 15 is kinked in this manner, the insertability of the treatment tool is significantly deteriorated, and in extreme cases, it becomes impossible to insert the treatment tool. Therefore, the flexible tube 15 must be replaced, but after the adhesive used for fixing the flexible tube 15 to the treatment instrument passage 16 is peeled off, the engagement of the through hole 15a with the pin 18 is released. By doing so, the flexible tube 15 can be easily attached and detached from the treatment instrument passage 16, so that the damaged flexible tube 15 can be easily replaced.

Next, FIGS. 6 and 7 show a second embodiment of the present invention. In this embodiment, the inner surface of the treatment instrument passage 22 of the distal end hard portion 21 is not provided with a pin. One or a plurality of protrusions 24 forming a stopper portion are provided at a portion of the flexible tube 23 through which the flexible tube 23 is inserted. The projection 24 is formed in a rectangular shape from the viewpoint of workability and the like, and the projection height from the inner surface of the treatment instrument passage 22 is substantially the same as the thickness of the flexible tube 23. Further, the flexible tube 23 is provided with a through hole 23a to be fitted into the protrusion 24. The through hole 23a is provided with the projection 24.
The width of the flexible tube 23 in the axial direction is substantially the same as the width of the projection 24 in the axial direction of the treatment instrument passage 22.
Thus, when the flexible tube 23 is fitted to the protrusion 24, it can be fixed so as not to move in the axial direction.

With this structure as well, the through hole 23a of the flexible tube 23 is fitted to the projection 24, and an adhesive is used between the outer surface of the flexible tube 23 and the inner surface of the treatment instrument passage 22. By fixing, the flexible tube 23 is held so as not to deviate from the treatment instrument passage 22 of the distal end hard portion 21 as in the first embodiment described above. Also,
Since the flexible tube 23 is directly inserted into the treatment instrument passage 22, the treatment instrument can be smoothly guided even when the angle operation is performed.

Furthermore, FIGS. 8 to 10 show a third embodiment of the present invention. In this embodiment, in order to fix the flexible tube 31 to the distal end hard portion 30a of the insertion portion 30, The metal pipe 32 is used. Thus, the distal end portion of the flexible tube 31 and the metal pipe 32 are provided with a plurality of through holes 31a and 32a at corresponding portions on the peripheral body portion thereof. A ridge 32b is formed on the distal end side, with which the distal end surface of the flexible tube 31 abuts. The distal end of the ridge 32b is a treatment tool outlet opening in a tapered shape.

First, as shown in FIG. 9, an adhesive is applied to the outer surface of the distal end portion of the flexible tube 31,
The flexible tube 3 is inserted into the metal pipe 32 at this time.
The direction of the through hole 31a of No. 1 is adjusted so as to coincide with the through hole 32a of the metal pipe 32, and the tip end surface of this flexible tube 31 is pushed to a position where it abuts against the ridge 32b of the metal pipe 32. As a result, the through holes 31a and 32a are connected in a completely matched state. Then, as shown in FIG. 10, the adhesive 33 is filled in the through holes 31a and 32a. However, the adhesive 33 is set so as not to protrude from the inner surface side of the flexible tube 31 and the outer surface side of the metal pipe 32, and the adhesive 33 is cured. by this,
The flexible tube 31 is firmly fixed to the metal pipe 32. Of course, since the flexible tube 31 is formed of a resin material, there is a limit to the adhesive force between the flexible tube 31 and the metal pipe 32, but the adhesive 33 that is filled between the through holes 31a and 32a and hardened is It serves as a stopper portion and is held so as not to deviate from the metal pipe 32 even if a strong pulling force is applied to the flexible tube 31.

In this way, the flexible tube 31 combined with the metal pipe 32 is inserted into the treatment instrument passage 34 provided in the distal end hard portion 30a and fixed by the adhesive 35, so that FIG. Assembled as shown. Further, if necessary, a screw hole 36 that opens into the treatment instrument passage 34 is provided in the distal end hard portion 30, and a locking screw 37 is screwed into the screw hole 36, so that the metal pipe inserted into the treatment instrument passage 34. It is pressed against the outer surface of 32.

With the above construction, even when the angled portion is curved, no step is formed in the passage for guiding the treatment instrument, and the treatment instrument can be smoothly inserted. Moreover, the flexible tube 31 is connected to the distal end hard portion 30 in an extremely stable state, and even if a strong pulling force is applied when the angle portion is bent, the flexible tube 31 does not fall off from the treatment instrument passage 34. That is, since the metal pipe 32 is directly fitted into the treatment instrument passage 34 and the metal is bonded to each other, there is no possibility that the metal pipe 32 and the metal pipe 32 are firmly fixed to each other and that the metal pipe 32 and the metal pipe 32 deviate unintentionally. And the flexible tube 3
In No. 1, not only is the metal pipe 32 and its outer surface adhered and fixed with an adhesive, but also the adhesive 33 interposed between the through holes 31a and 32a functions as a stopper portion. It is also firmly connected and held with 32.

Moreover, the flexible tube 31 is connected to the metal pipe 3
2 and the through holes 31a and 32a are filled and hardened with the adhesive 33, the assembly is inserted into the treatment instrument passage 34 and fixed by the adhesive 35.
Since the flexible tube 31 can be attached to the distal end hard portion 30, it is extremely easy to attach and detach the flexible tube 31, and it is convenient to replace the flexible tube 31 when a damage such as a kink occurs.

[0032]

As described above, according to the present invention, one or a plurality of through holes are formed in the insertion portion of the flexible tube into the treatment tool passage, and the through hole is fixed to the treatment tool passage side. Since the stopper portion that is engaged is configured to be engaged with the inner surface of the flexible tube in a non-protruding state, the flexible tube can be securely fixed even if the length of the hard portion at the tip of the insertion portion is minimized, and The effect that the treatment tool can be smoothly inserted is obtained.

[Brief description of drawings]

FIG. 1 is an end view of a distal end portion of an insertion portion including a treatment tool insertion channel fixing mechanism according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is an external view of a distal end portion of a flexible tube.

FIG. 4 is an enlarged view of a main part of FIG.

FIG. 5 is an operation explanatory view showing a mounting state of the flexible tube in the treatment instrument passage.

FIG. 6 is a configuration explanatory view of a fixing mechanism of a treatment instrument insertion channel showing a second embodiment of the present invention.

FIG. 7 is an operation explanatory view showing a mounting state of the flexible tube in the treatment instrument passage in the second embodiment.

FIG. 8 is a sectional view of a main part of a distal end hard portion of an insertion portion showing a configuration of a treatment instrument insertion channel fixing mechanism showing a third embodiment of the present invention.

FIG. 9 is an external view of a state before connection between the flexible tube and the metal pipe.

FIG. 10 is an external view of a connected state of a flexible tube and a metal pipe.

FIG. 11 is a structural explanatory view of a treatment instrument insertion channel fixing mechanism according to a conventional technique.

FIG. 12 is a diagram for explaining the operation of FIG.

[Explanation of symbols]

 10, 30 Insertion part 10a, 21, 30a Tip hard part 14 Treatment tool insertion channel 15, 23, 31 Flexible tube 15a, 23a, 31a, 32a Through hole 16, 22, 34 Treatment tool passage 17 Pin insertion hole 18 pin 24 Protrusion 33 Adhesive

Claims (4)

[Claims] 1. A treatment instrument passage for inserting a treatment instrument, comprising: a treatment instrument passage provided in a distal end hard portion in an insertion portion of an endoscope; and a flexible tube having a tip connected to the treatment instrument passage. In the channel, the flexible tube is inserted into the treatment instrument passage, connected and fixed using an adhesive, and one or a plurality of through holes are formed in the insertion portion of the flexible tube into the treatment instrument passage. Then, a stopper portion fixed to the treatment instrument passage side is engaged in the through hole so as not to project from the inner surface of the flexible tube. Fixing mechanism. 2. The endoscope according to claim 1, wherein the stopper portion is formed by a stopper piece that is mounted and fixed so as to project from the peripheral body portion of the distal end hard portion to the inner surface of the treatment instrument passage. Mechanism for fixing the treatment instrument insertion channel. 3. The treatment instrument insertion channel fixing mechanism for an endoscope according to claim 1, wherein the stopper portion is formed by providing a convex portion on an inner wall of the treatment instrument passage of the distal end hard portion. 4. A metal pipe is interposed between the flexible tube and the treatment instrument passage, and the metal pipe is provided with a through hole at a portion corresponding to the through hole of the flexible tube. The flexible tube fixing mechanism for an endoscope according to claim 1, wherein an adhesive forming a stopper portion is filled between the through hole of the tube and the through hole of the metal pipe.