Detachable and retractable pen

1. A detachable and retractable pen, comprising:

a holder;

a barrel;

a cap; and

a push component;

wherein the holder is in threaded connection with a front end of the barrel; the cap is in snap-fit with a rear end of the barrel; the barrel and the holder are configured to receive a refill; the push component is configured to drive the refill to slide axially along the barrel; a first hole is provided on an outer wall of the rear end of the barrel to enable the push component to slide axially in the barrel; a reset spring is provided between an end of the push component inside the barrel and the cap; the refill is engaged with a front portion of the push component in the barrel;

two limit clamps are symmetrically provided in the push component; and the two limit clamps are in snap-fit with the barrel, respectively;

two fixing structures are symmetrically provided on an inner wall of the rear end of the barrel for positioning of the two limit clamps; a guide structure is provided on the inner wall of the rear end of the barrel and is configured to drive the two limit clamps to respectively clamp with the fixing structures;

when the push component is pushed backwards, the two limit clamps separate from the fixing structures and the two limit clamps approach each other; and the reset spring is pressed by the push component to slide axially along the barrel to a first position;

when the push component is released, the push component is driven under an action of the reset spring to slide axially along the barrel to a second position, such that the guide structure drives the two limit clamps to separate from each other and be respectively in snap-fit with the fixing structures again and a tip of the refill emerges from the holder;

when pushed backwards again, the push component drives the two limit clamps to separate from the fixing structures and then be in snap-fit with the fixing structures again such that the tip of the refill is hidden in the holder;

the push component comprises a pen clip and a sliding cylinder; the pen clip is fixedly connected to a side of the sliding cylinder and is located outside the barrel; a rear portion of the sliding cylinder is fixed with a positioning cylinder; the reset spring is located between the positioning cylinder and the cap; a connecting plate is fixed on an inner wall of a front portion of the sliding cylinder, a pen groove is formed between the connecting plate and the inner wall of front portion of the sliding cylinder to enable the refill to be in snap-fit therewith; an outer wall of the sliding cylinder is provided with two second holes which are symmetrical with respect to an axis of the sliding cylinder; and the two limit clamps are fixed at a rear side of the connecting plate;

each limit clamp comprises one limit fixture block, the two limit fixture blocks are symmetrically fixed at the rear side of the connecting plate; a sliding surface is provided on an outer wall of a rear portion of each limit fixture block; ends of the limit fixture blocks away from the connecting plate protrude from the second holes and are respectively in snap-fit with the fixing structures; the rear portion of each limit fixture block is fixed with a magnet column; adjacent magnetic poles of the two magnet columns are opposite; and a magnetic attraction force between the two magnet columns is less than an elastic force of the reset spring;

each fixing structure comprises a first groove and a second groove; the first groove and the second groove are provided on the inner wall of the rear end of the barrel; a rear portion of the first groove is provided with a first guide surface; a rear portion of the second groove is provided with a second guide surface; the end of each limit fixture block away from the connecting plate is clamped in the first groove; and the sliding surface is in contact with the first guide surface.

2. The detachable and retractable pen of claim 1 , wherein a distance between a rear end of the first hole and a rear end of the pen clip is larger than or equal to a maximum elastic displacement of the reset spring, and smaller than or equal to a distance between the positioning cylinder and the cap.

3. The detachable and retractable pen of claim 1 , wherein opposite surfaces of the two limit fixture blocks are provided with a positioning block and a positioning groove, respectively; and the positioning block and the positioning groove are in snap-fit with each other.

4. The detachable and retractable pen of claim 1 , wherein the first guide surface is larger than the second guide surface in area.

5. The detachable and retractable pen of claim 1 , wherein the guide structure comprises a cushion block fixed on the inner wall of the rear end of the barrel and a guide column fixed on the cushion block; the cushion block is provided at an inner wall of a side of the barrel away from the pen clip, and located at a center line of the two limit fixture blocks; and a maximum distance between the cushion block and the inner wall of the side of the barrel away from the pen clip is lower than a maximum distance between the first groove and the inner wall of the side of the barrel away from the pen clip and a maximum distance between the second groove and the inner wall of the side of the barrel away from the pen clip; and the guide column is located between the two limit fixture blocks.

6. The detachable and retractable pen of claim 5 , wherein a maximum distance between a surface of the guide column close to the pen clip and the inner wall of the side of the barrel away from the pen clip is larger than a maximum distance between a surface of each limit fixture block away from the pen clip and the inner wall of the side of the barrel away from the pen clip.

7. The detachable and retractable pen of claim 1 , wherein a positioning protrusion is fixed on a surface of the cap located inside the barrel; and the positioning protrusion is inserted into the reset spring.