Endoscope treatment tool

1. An endoscope treatment tool comprising:

a clip unit having a clip main body which includes first and second arm portions and a locked portion which protrudes from the clip main body, the clip unit including a pressing tube which is formed in a tube shape to be capable of accommodating the clip main body and provided to make a distal end of the first arm portion and a distal end of the second arm portion approach to each other as the clip main body is moved toward a proximal end side of the pressing tube, the pressing tube including a locking portion which protrudes from an inner circumferential surface of a proximal end of the pressing tube;

a linear member having a distal end portion connected to the clip unit and provided to manipulate the clip main body by being advanced and retracted;

a sheath portion being inserted into a channel of an endoscope, wherein the linear member is inserted into the sheath portion so that the linear member is advanceable and retractable; and

a manipulation portion having a manipulation portion main body connected to a proximal end portion of the sheath portion, a slider configured to be movable relative to the manipulation portion main body, and a fracture mechanism configured to connect a proximal end portion of the linear member and the slider, the manipulation portion being manipulated at a proximal end side of the channel when the sheath portion is inserted into the channel,

wherein the fracture mechanism includes:

a first support member connected to the proximal end portion of the linear member,

a second support member disposed on a proximal end side of the first support member and connected to the slider, and

a fracturable member disposed between the first support member and the second support member so as to connect the first support member and the second support member, the fracturable member being configured such that a fracture strength of the fracturable member against a tensile force applied to pull the linear member in an axial line direction is lower than a fracture strength of the first support member and a fracture strength of the second support member,

wherein a force necessary to make the fracturable member to be fractured is configured to be higher than a force necessary to move the locked portion proximally beyond the locking portion.

2. The endoscope treatment tool according to claim 1 ,

wherein the fracture mechanism is disposed inside the manipulation portion,

and wherein the fracturable member is fractured when an amount of a manipulation force by the slider reaches a value equal to or greater than a predetermined value, when the slider is continuously pulled after the clip main body is moved such that the locked portion is located more proximally than the locking portion.

3. The endoscope treatment tool according to claim 2 , wherein

the clip unit is fixed in a closed state that the first and second arm portions are closed by moving the clip main body until the locked portion is located proximally beyond the locking portion, and

the fracture mechanism is configured so as to allow an operator to identify, upon the occurrence of the fracture of the fracturable member, that the clip unit has been fixed in the closed state.

4. The endoscope treatment tool according to claim 3 , wherein

the fracturable member is formed as a plate and is configured such that a width of a middle fraction portion of the fracturable member is narrower than a width of a first end portion of the fracturable member connected to the first support member and a width of a second end portion of the fracturable member connected to the second support member, and

fracture strength of the middle fracture portion of the fracturable member is set to be lower than the first and second end portions.

5. The endoscope treatment tool according to claim 4 , wherein

the fracture mechanism includes an elastic member connected to the first and second support members, and

wherein a connection state of the first and second support members is maintained by the elastic member after the fracturable member is fractured.

6. An endoscope treatment tool comprising:

a clip unit having a clip main body which includes first and second arm portions, a pressing tube which is formed in a tube shape to be capable of accommodating the middle portion and the clip main body and provided to make a distal end of the first arm portion and a distal end of the second arm portion approaching to each other as the clip main body is moved toward a proximal end side of the pressing tube, a locking portion which protrudes from an inner circumferential surface of a proximal end of the pressing tube, and a locked portion which protrudes from the clip main body;

a linear member connected to the clip unit and provided to manipulate the clip main body by being advanced and retracted;

a sheath in which the linear member is inserted so that the linear member is advanceable and retractable; and

a fracture mechanism connected to a proximal end of the linear member,

wherein the fracture mechanism includes:

a first support member connected to the linear member,

a second support member disposed on a proximal end side of the first support member, and

a fracturable member disposed between the first support member and the second support member so as to connect the first support member and the second support member, the fracturable member being configured such that a fracture strength of the fracturable member against a tensile force applied to pull the linear member in an axial line direction is lower than a fracture strength of the first support member and a fracture strength of the second support member,

wherein a force necessary to make the fracturable member to be fractured is configured to be higher than a force necessary to move the clip main body accommodated in the pressing tube so that the locked portion is located on a proximal end side of the locking portion and beyond the locking portion;

the fracture mechanism includes an elastic member connected to the first and second support members, and

after the fracturable member is fractured, a connection state of the first and second support members is maintained by the elastic member.