Refillable pen with automatic extension and retraction of the refill

Abstract

The application discloses a refill automatic telescopic pen, which comprises a pen barrel, a refill, and a refill self-locking mechanism, the refill self-locking mechanism is supported at the rear end of the refill, a first spring is arranged between the front end of the refill and the pen barrel, the refill self-locking mechanism comprises a sleeve, a connecting rod, a counterweight, a sliding block and a second spring, the sleeve is provided with a window at the side, the sliding block is horizontally movably arranged at the window of the sleeve, the front end of the connecting rod is movably arranged at the inner side of the sleeve and is in transmission connection with the sliding block, the rear end of the connecting rod is connected with the counterweight, the second spring acts between the sleeve and the connecting rod, the connecting rod and the sleeve are in guiding movement cooperation through a convex shaft and an inclined guide groove arranged between the connecting rod and the sleeve, and the front part of the pen barrel is provided with a counterweight for balancing the gravity center. The refill automatic telescopic pen has the advantages of less parts and simple structure.

Description

Technical Field

[0001] This invention relates to a pen with an automatically retractable lead. Background Technology

[0002] Currently, there are pens on the market that can automatically extend and retract the pen tip based on gravity. When the pen is placed vertically, the pen tip extends automatically under the action of gravity and remains in the extended position, making it convenient for writing. When the pen is placed horizontally or upside down, the pen tip retracts automatically into the pen barrel, achieving automatic retraction. This type of pen can reduce user operations and is more convenient to use.

[0003] Currently, there are two types of pens that automatically extend the lead based on gravity. One type adopts the solution shown in the Chinese invention patent "Automatic Reset Pen Linkage Structure" (CN221698336U), which includes a lead, outer shell, counterweight, reset structure, transmission component, and locking component. The transmission component consists of a first connecting component, a connecting rod, a rotating component, and a second connecting component connected in sequence. The extension or retraction of the lead is achieved through the coordinated cooperation between the counterweight, reset structure, and transmission component. The other type adopts the solution shown in the Chinese invention patent "Writing Tool with Telescopic Component Ball Locking Structure" (CN106274162B), which has a forward / backward component, a rolling element, etc. The rolling element contacts the side of the forward / backward component, and the telescopic component is locked by means of components such as a locking component.

[0004] The two types of pens mentioned above are quite complex and require higher standards for manufacturing and assembly processes. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention provides a pen with fewer parts, a simpler structure, and an automatically retractable refill tip.

[0006] The present invention relates to an automatically retractable pen, comprising a pen barrel, a pen refill disposed within the pen barrel, and a pen refill self-locking mechanism. The pen refill self-locking mechanism is supported at the rear end of the pen refill and can move along the front-back direction of the pen. A first spring is disposed between the front end of the pen refill and the pen barrel. The pen refill self-locking mechanism includes a sleeve, a connecting rod, a counterweight, a slider, and a second spring. A window is provided on the side of the sleeve. The slider is laterally movable at the window of the sleeve. The front end of the connecting rod moves along the front-back direction through the inner side of the sleeve and is connected and engaged with the slider. The rear end of the connecting rod is connected to the counterweight. The block is preferably made of metal. The second spring acts between the sleeve and the connecting rod and drives the connecting rod to move backward relative to the sleeve. The connecting rod and the sleeve are guided by a convex shaft and an inclined guide groove between them. This allows the connecting rod to drive the slider to move laterally outward and inward along the window of the sleeve when it moves forward and backward relative to the sleeve, respectively. When the slider extends, it forms an abutment with the inner wall of the pen barrel. The inner side of the pen barrel is provided with a limiting part that cooperates with and limits the front end of the sleeve. The front part of the pen barrel is provided with a counterweight for balancing the center of gravity. The counterweight is preferably made of metal.

[0007] When the pen is in use, it is held vertically. The pen refill locking mechanism and the pen refill move forward against the elastic force of the first spring under the action of gravity, causing the pen refill to extend from the front end of the pen barrel. During the forward movement of the pen refill locking mechanism, when the front end of the sleeve moves to the position limited by the limiting part, the counterweight and connecting rod move forward relative to the sleeve under the action of gravity against the elastic force of the second spring. At the same time, the slider is driven to extend laterally outward along the window of the sleeve. The slider and the inner wall of the pen barrel form an abutting fit. During writing, due to the damping between the slider and the inner wall of the pen barrel, the pen refill can be locked in the refill position, preventing the pen refill from retracting due to writing pressure. When the pen is not in use, it is held horizontally. The direction of gravity of the pen refill and the pen refill locking mechanism is no longer in the same direction as the elastic force of the first and second springs. The counterweight and connecting rod move backward relative to the sleeve under the action of the second spring, causing the slider to retract laterally inward. The pen refill and the pen refill locking mechanism as a whole move backward under the action of the first spring, realizing the automatic refill function.

[0008] Compared with existing technologies, the above-mentioned solution for automatic pen retraction has fewer parts, a simpler structure, and simpler assembly and processing of parts. It is also more reliable and less prone to jamming.

[0009] Furthermore, the slider includes a sleeve portion and an abutment portion. The abutment portion is located on one side of the sleeve portion. The sleeve portion and the connecting rod form a movable sleeve fit. The guide groove is located on the side of the sleeve portion, and the convex shaft is located on the connecting rod. When the connecting rod moves back and forth relative to the slider, the slider moves laterally in conjunction with the convex shaft and the guide groove.

[0010] Furthermore, guide grooves are symmetrically arranged on both sides of the sleeve portion, and the guide grooves penetrate the inner and outer sides of the sleeve portion. A connecting hole is provided on the connecting rod, and the convex shaft is composed of the two ends of a metal rod that is fixedly inserted into the connecting hole. During assembly, the connecting rod is first inserted into the sleeve portion, and then the metal rod is inserted into the connecting hole of the connecting rod along the guide groove for installation and positioning. The structure is simple and the assembly is convenient.

[0011] Furthermore, an annular baffle is provided on the inner side of the sleeve near the rear end, and a movable cavity is formed between the rear end of the sleeve and the annular baffle. A connecting block is provided at the rear end of the connecting rod, and the connecting block is movably disposed in the movable cavity. The connecting rod is connected and cooperates with the front end of the counterweight through the connecting block. The second spring is sleeved on the connecting rod and abuts and cooperates with the annular baffle and the connecting block respectively. The overall structure is simple and compact, ensuring the stability of the force direction of the second spring.

[0012] Furthermore, the rear end of the connecting block is provided with a plug-in hole, and the front end of the counterweight block is provided with a plug-in block that cooperates with the plug-in hole for positioning, so as to realize the fixed cooperation between the counterweight block and the connecting rod and avoid the counterweight block from shaking; the front end of the sleeve is provided with a positioning hole that cooperates with the rear end of the pen refill for positioning, so as to realize the relative fixation between the sleeve and the pen refill and improve the cooperation effect.

[0013] Furthermore, the pen barrel includes a front section, a rear section, and a connecting section. The front end of the connecting section is screwed to the rear end of the inner hole of the front section, and the rear end of the connecting section is inserted and positioned at the front end of the inner hole of the rear section. The limiting part is formed by the rear end of the connecting section. The rear end side of the connecting section and the inner hole sidewall of the rear section are circumferentially limited by a sliding groove and a protrusion arranged along the front-back direction of the pen. During installation, the rear end of the connecting section can be inserted into the rear section of the pen barrel first. When the rear section is rotated relative to the front section, the screw connection between the front end of the connecting section and the front section can be achieved, which is relatively convenient. The rear end side of the connecting section and the inner hole sidewall of the rear section are axially limited by two annular protrusions arranged along the circumference of the pen, which can prevent the rear end of the connecting section from coming out of the inner hole of the rear section.

[0014] Furthermore, the counterweight is a cylindrical counterweight (including a ring-shaped one), which is placed inside the pen barrel and sleeved on the outside of the pen refill. The cylindrical counterweight can be a spirally wound metal wire. The cylindrical counterweight is used to adjust the center of gravity of the pen and improve the writing feel. The counterweight with this structure is simple and easy to assemble.

[0015] Furthermore, a pen clip is provided on the rear side of the pen barrel, which can move back and forth relative to the pen barrel. A locking member is movably arranged between the pen clip and the pen barrel. An opening is provided on the side of the pen barrel. When the pen clip moves relative to the pen barrel, it can drive the locking end of the locking member to extend into the inside of the pen barrel along the opening or retract. The front and rear sides of the counterweight block both include positioning parts that can form a locking and positioning engagement with the locking end of the locking member when it extends into the inside of the pen barrel. The front edge of the counterweight block can serve as the positioning part of its front side, and the annular groove in the middle of the counterweight block can serve as the positioning part of its rear side. When the locking end of the locking member and the positioning part of the counterweight block are locked together, the counterweight block can be held in its current position, thereby keeping the pen refill in the extended or retracted position, so that it is not affected by the posture of the pen. For example, it can still maintain the extended position when the pen is placed horizontally, and it can still maintain the retracted position when the pen is placed vertically. In particular, it can prevent the pen refill from extending automatically when the pen is carried with you.

[0016] Furthermore, the snap-fit ​​component is a metal spring sheet disposed between the pen clip and the pen barrel. One end of the metal spring sheet is a snap-fit ​​end, and the other end is a fixed end. A bent portion is formed between the snap-fit ​​end and the fixed end. The fixed end is fixed to the inside of the pen clip. A notch is formed between the pen clip and the pen barrel, into which the bent portion of the metal spring sheet can be inserted. This notch is located near the opening on the side of the pen barrel. The notch includes a side wall adjacent to the opening, and the snap-fit ​​end and the side wall form an elastic pressing fit. When the pen clip moves back and forth relative to the pen barrel, it can also drive the metal spring sheet to move back and forth relative to the pen barrel. Since the snap-fit ​​end of the metal spring sheet presses against the side wall of the notch, it can move along the side wall with the movement of the pen clip. When it moves to the opening, it extends into the inside of the pen barrel under its own elasticity, and can cooperate with the counterweight.

[0017] Furthermore, a positioning rib is provided on the side wall of the notch, and a positioning groove is provided on the snap-fit ​​end to cooperate with the positioning rib for positioning. Through the cooperation of the positioning rib and the positioning groove, positioning can be formed between the metal spring and the pen barrel, thereby also keeping the pen clip and the pen barrel in position and preventing them from shaking. Attached Figure Description

[0018] Figure 1 This is an assembly diagram of an embodiment of the present invention; Figure 2 This is an assembly diagram of the pen refill self-locking mechanism according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the assembly of the slider and connecting rod according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the assembly of the pen clip and pen barrel according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the assembly of the pen clip and the metal spring in an embodiment of the present invention; Figure 6This is a schematic diagram of the connecting section of the pen barrel according to an embodiment of the present invention; Figure 7 This is a partial cross-sectional view of the core-shrinking state in an embodiment of the present invention; Figure 8 This is a partial cross-sectional view of the core-exit state in an embodiment of the present invention; Figure 9 This is a partial cross-sectional view of the first locking state of the counterweight block in an embodiment of the present invention; Figure 10 This is a partial cross-sectional view of the second locking state of the counterweight block in an embodiment of the present invention. Detailed Implementation

[0019] The structure of the automatically retractable pen according to an embodiment of the present invention is as follows: Figure 1-10 As shown, the pen includes a pen barrel (11, 12, 13), a pen refill 2 disposed inside the pen barrel, and a pen refill self-locking mechanism. The pen refill self-locking mechanism is supported at the rear end of the pen refill 2 and can move along the front-back direction of the pen. A first spring 3 is disposed between the front end of the pen refill 2 and the pen barrel. The pen refill self-locking mechanism includes a sleeve 41, a connecting rod 42, a counterweight 43, a slider 44, and a second spring 45. A window 411 is provided on the side of the sleeve 41. The slider 44 is laterally movable at the window 411 of the sleeve 41. The front end of the connecting rod 42 moves along the front-back direction. The connecting rod 42 is inserted into the inner side of the sleeve 41 and is connected to the slider 44 in a transmission connection. The rear end of the connecting rod 42 is connected to the counterweight 43. The second spring 45 acts between the sleeve 41 and the connecting rod 42 and is used to drive the connecting rod 42 to move backward relative to the sleeve 41. When the connecting rod 42 moves forward and backward relative to the sleeve 41, it can drive the slider 44 to move laterally outward and inward along the window 411 of the sleeve 41, respectively. When the slider 44 is extended, it forms an abutment with the inner wall of the pen barrel. The inner side of the pen barrel is provided with a limiting part that cooperates with and limits the front end of the sleeve 41.

[0020] When the pen is needed, it is held vertically. The self-locking mechanism and the pen refill 2 move forward against the elastic force of the first spring 3 under gravity, causing the pen refill 2 to extend from the front end of the pen barrel. During this forward movement, when the front end of the sleeve 41 reaches the position limited by the limiting part, the counterweight 43 and connecting rod 42 move forward relative to the sleeve 41 against the elastic force of the second spring 45 under gravity. Simultaneously, this drives the slider 44 to extend laterally outward along the window 411 of the sleeve 41. The slider 44 and the inner wall of the pen barrel form an abutting fit. During writing, due to the slider 44... When the pen is in contact with the inner wall of the pen barrel, there is damping, which can lock the pen tip 2 in the lead-out position and prevent the pen tip 2 from moving backward due to writing pressure. When the pen is not in use, the pen is placed horizontally, and the direction of gravity of the pen tip 2 and the pen tip self-locking mechanism is no longer in the same direction as the direction of the elastic force of the first and second springs 45. Under the action of the second spring 45, the counterweight 43 and the connecting rod 42 move backward relative to the sleeve 41, causing the slider 44 to retract laterally inward, releasing the lock between it and the pen barrel. The pen tip and the pen tip self-locking mechanism as a whole move backward under the action of the first spring 3, realizing the automatic lead retraction function.

[0021] Compared with existing technologies, the above-mentioned solution for automatic pen retraction has fewer parts, a simpler structure, and simpler assembly and processing of parts. It is also more reliable and less prone to jamming.

[0022] like Figure 2 , 3 As shown, the slider 44 includes a sleeve portion 441 and an abutment portion 442. The abutment portion 442 is disposed on one side of the sleeve portion 441. The sleeve portion 441 and the connecting rod 42 form a movable sleeve fit. Inclined guide grooves 443 are symmetrically arranged on both sides of the sleeve portion 441. The guide grooves 443 penetrate the inner and outer sides of the sleeve portion 441. The connecting rod 42 is provided with a convex shaft that forms a guiding motion fit with the guide grooves 443. When the connecting rod 42 moves back and forth relative to the slider 44, the slider 44 moves laterally in conjunction with the convex shaft and the guide grooves 443. The connecting rod 42 is provided with a connecting hole 421. The convex shaft is composed of the two ends of a metal rod 422 that are fixedly inserted into the connecting hole 421. During assembly, the connecting rod 42 is first inserted into the sleeve portion 441, and then the metal rod 422 is inserted into the connecting hole 421 of the connecting rod 42 along the guide grooves 443 for installation and positioning. The structure is simple and the assembly is convenient.

[0023] An annular baffle 412 is provided on the inner side of the sleeve 41 near the rear end. A movable cavity is formed between the rear end of the sleeve 41 and the annular baffle 412. A connecting block 423 is provided at the rear end of the connecting rod 42. The connecting block 423 is movably disposed in the movable cavity. The connecting rod 42 is connected and cooperates with the front end of the counterweight block 43 through the connecting block 423. The second spring 45 is sleeved on the connecting rod 42 and abuts against the annular baffle 412 and the connecting block 423 respectively. The overall structure is simple and compact, ensuring the stability of the force direction of the second spring 45.

[0024] The rear end of the connecting block 423 is provided with a plug-in hole, and the front end of the counterweight block 43 is provided with a plug-in block that cooperates with the plug-in hole for positioning, so as to realize the fixed cooperation between the counterweight block 43 and the connecting rod 42 and prevent the counterweight block 43 from shaking; the front end of the sleeve 41 is provided with a positioning hole that cooperates with the rear end of the pen refill 2 for positioning, so as to realize the relative fixation between the sleeve 41 and the pen refill 2 and improve the cooperation effect.

[0025] like Figure 1 , 6 As shown in Figures 7 and 8, the pen barrel includes a front section 11, a rear section 13, and a connecting section 12. The front end of the connecting section 12 is screwed to the rear end of the inner hole of the front section 11, and the rear end of the connecting section 12 is inserted and positioned at the front end of the inner hole of the rear section 13. The limiting part is formed by the rear end of the connecting section 12 (used to limit the farthest distance of the sleeve 41 moving forward). The rear end side of the connecting section 12 and the inner hole sidewall of the rear section 13 are circumferentially limited by a sliding groove and a protrusion 121 arranged along the front-back direction of the pen. During installation, the rear end of the connecting section 12 can be inserted into the rear end of the pen barrel first. In segment 13, when the rear segment 13 rotates relative to the front segment 11, the connecting segment 12 and the rear segment 13 are circumferentially limited, which can realize the screw connection between the front end of the connecting segment 12 and the front segment 11, making the operation relatively convenient. The rear end side of the connecting segment 12 and the inner wall of the rear segment 13 are axially limited by two annular ribs arranged along the circumference of the pen. The connecting segment 12 is axially limited (i.e., limited along the length direction of the pen) through the annular rib 122 on its rear end side and the pen barrel, which can prevent the rear end of the connecting segment 12 from coming out forward from the inner hole of the rear segment 13.

[0026] The pen barrel has a cylindrical counterweight 5 (including an annular shape) at its front. The cylindrical counterweight 5 is located inside the pen barrel and sleeved on the outside of the pen refill 2. The cylindrical counterweight 5 can be a spirally wound metal wire, such as... Figure 1 , 7 As shown in Figure 8, the cylindrical counterweight 5 is used to adjust the center of gravity of the pen and improve the writing feel.

[0027] like Figure 4 , 59, 10. A pen clip 6 is provided on the rear side of the pen barrel (i.e., the rear section 13). The pen clip 6 can move back and forth within a certain range relative to the pen barrel. A snap-fit ​​component 7 is movably provided between the pen clip 6 and the pen barrel. An opening 131 is provided on the side of the pen barrel. When the pen clip 6 moves forward relative to the pen barrel, it can drive the snap-fit ​​end 71 of the snap-fit ​​component 7 to extend into the inside of the pen barrel along the opening 131. When it moves backward, the snap-fit ​​end 71 retracts along the opening 131. The front and rear sides of the counterweight block 43 both include positioning parts that can form a snap-fit ​​positioning engagement with the snap-fit ​​end 71 of the snap-fit ​​component 7 when it extends into the inside of the pen barrel. In this embodiment, the front edge of the counterweight block 43 serves as the positioning part of its front side, and the annular groove 431 opened in the middle of the counterweight block 43 serves as the positioning part of its rear side. When the snap-fit ​​end 7 of the snap-fit ​​component 7 and the positioning part of the counterweight 43 snap into each other, the counterweight 43 can be held in its current position, such as Figure 9 As shown, when the counterweight 43 is in the rear position (corresponding to the retracted core state), the front edge of the counterweight 43 is engaged and positioned by the locking end 71. Since the pen clip 6 is in the front position, it cannot move forward, which also prevents the counterweight 43 from moving forward. Figure 10 As shown, when the counterweight 43 is in the forward position (corresponding to the lead extension state), it is engaged and positioned by the locking end 71 with the annular groove 431 of the counterweight 43. Since the pen clip 6 is in the rear position, it cannot move backward, which also prevents the counterweight 43 from moving backward. This keeps the pen lead 2 in the lead extension or retraction position, unaffected by the pen's posture. That is, whether the pen is placed vertically or horizontally, it can prevent the pen lead from automatically extending or retracting. Especially when carrying a pen, it can prevent the pen lead 2 from automatically extending, providing some protection for the pen lead 2 and preventing it from soiling other items in the bag. In addition, it can also increase the tilt angle of the pen when writing, preventing the pen lead from retracting on its own.

[0028] The snap-fit ​​component 7 is a metal spring sheet disposed between the pen clip 6 and the pen barrel. One end of the metal spring sheet is a snap-fit ​​end 71, and the other end is a fixed end 72. A bent portion 73 is formed between the snap-fit ​​end 71 and the fixed end 72. The fixed end is fixed to the inside of the pen clip 6. A recess 8 is formed between the pen clip 6 and the pen barrel, into which the bent portion 73 of the metal spring sheet can be inserted. The recess 8 is located close to the opening 131 on the side of the pen barrel. The recess 8 includes a side wall adjacent to the opening 131. The snap-fit ​​end 71 and the side wall form an elastic pressing fit. When the pen clip 6 moves back and forth relative to the pen barrel, it can also drive the metal spring sheet to move back and forth relative to the pen barrel. Since the snap-fit ​​end 71 of the metal spring sheet presses against the side wall of the recess 8, it can move along the side wall with the movement of the pen clip 6. When it moves forward to the opening 131, it extends into the inside of the pen barrel under its own elastic action, and can cooperate with the counterweight 43 (e.g., Figure 9 , 10 (The state shown).

[0029] The side wall of the notch 8 is provided with a positioning rib 81, and the snap-fit ​​end 71 is provided with a positioning groove 711 that cooperates with the positioning rib 81 for positioning. Through the cooperation of the positioning rib 81 and the positioning groove 711, positioning can be formed between the metal spring and the pen barrel, thereby achieving positioning between the pen clip 6 and the pen barrel when the pen clip 6 moves backward to the end position, and preventing the pen clip 6 from shaking.

[0030] The above embodiments are merely one preferred embodiment of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solution of the present invention are all included within the protection scope of the present invention.

Claims

1. A pen with an automatically retractable retractable lead, comprising a pen barrel, a lead disposed within the pen barrel, and a lead self-locking mechanism, the lead self-locking mechanism being supported at the rear end of the lead and capable of moving along the front-rear direction of the pen, and a first spring disposed between the front end of the lead and the pen barrel, characterized in that: The self-locking mechanism of the pen refill includes a sleeve, a connecting rod, a counterweight, a slider, and a second spring. A window is provided on the side of the sleeve, and the slider is laterally movable at the window. The front end of the connecting rod moves along the front-back direction through the inner side of the sleeve and is connected to the slider in a transmission manner. The rear end of the connecting rod is connected to the counterweight. The second spring acts between the sleeve and the connecting rod, driving the connecting rod to move backward relative to the sleeve. The connecting rod and the sleeve are guided by a convex shaft and an inclined guide groove, which allows the connecting rod to move backward. When the connecting rod moves forward and backward relative to the sleeve, it can drive the slider to move laterally outward and inward along the window of the sleeve, respectively. When the slider extends, it forms an abutment with the inner wall of the pen barrel. The inner side of the pen barrel is provided with a limiting part that cooperates with and limits the front end of the sleeve. The front part of the pen barrel is provided with a counterweight for balancing the center of gravity. The slider includes a sleeve part and an abutment part. The abutment part is located on one side of the sleeve part. The sleeve part and the connecting rod form a movable sleeve fit. The guide groove is located on the side of the sleeve part. The convex shaft is located on the connecting rod.

2. The pen with an automatically retractable refill as described in claim 1, characterized in that: The sleeve portion has symmetrical guide grooves on both sides, which penetrate the inner and outer sides of the sleeve portion. The connecting rod has a connecting hole, and the convex shaft is composed of the two ends of a metal rod that is fixedly inserted into the connecting hole.

3. The pen with an automatically retractable refill as described in claim 1, characterized in that: An annular baffle is provided on the inner side of the sleeve near the rear end. A movable cavity is formed between the rear end of the sleeve and the annular baffle. A connecting block is provided at the rear end of the connecting rod. The connecting block is movably disposed in the movable cavity. The connecting rod is connected and cooperates with the front end of the counterweight block through the connecting block. The second spring is sleeved on the connecting rod and abuts and cooperates with the annular baffle and the connecting block respectively.

4. The pen with an automatically retractable refill as described in claim 3, characterized in that: The rear end of the connecting block is provided with a plug-in hole, and the front end of the counterweight block is provided with a plug-in block that is inserted and positioned in conjunction with the plug-in hole; the front end of the sleeve is provided with a positioning hole that is inserted and positioned in conjunction with the rear end of the pen refill.

5. The pen with an automatically retractable refill as described in claim 1, characterized in that: The pen barrel includes a front section, a rear section, and a connecting section. The front end of the connecting section is screwed to the rear end of the inner hole of the front section, and the rear end of the connecting section is inserted and positioned at the front end of the inner hole of the rear section. The limiting part is formed by the rear end of the connecting section. The rear end side of the connecting section and the side wall of the inner hole of the rear section are circumferentially limited by a sliding groove and a protrusion arranged along the front-back direction of the pen. The rear end side of the connecting section and the side wall of the inner hole of the rear section are axially limited by two annular ribs arranged along the circumference of the pen.

6. The pen with an automatically retractable refill as described in claim 1, characterized in that: The counterweight is a cylindrical counterweight, which is placed inside the pen barrel and sleeved on the outside of the pen refill.

7. The pen with an automatically retractable refill as described in claim 1, characterized in that: The pen barrel has a pen clip at its rear end, which can move back and forth relative to the pen barrel. A snap-fit ​​device is movably connected between the pen clip and the pen barrel. The pen barrel has an opening on its side. When the pen clip moves relative to the pen barrel, it can drive the snap-fit ​​end of the snap-fit ​​device to extend into the inside of the pen barrel or retract it. The counterweight has a positioning part at its front and rear sides, which can engage with the snap-fit ​​end of the snap-fit ​​device when it extends into the inside of the pen barrel.

8. The pen with an automatically retractable refill as described in claim 7, characterized in that: The snap-fit ​​component is a metal spring sheet disposed between the pen clip and the pen barrel. One end of the metal spring sheet is a snap-fit ​​end, and the other end is a fixed end. A bent portion is formed between the snap-fit ​​end and the fixed end. The fixed end is fixed to the inside of the pen clip. A notch is formed between the pen clip and the pen barrel, into which the bent portion of the metal spring sheet can be inserted. The notch is located close to the opening on the side of the pen barrel. The notch includes a side wall adjacent to the opening. The snap-fit ​​end and the side wall form an elastic pressing fit.

9. The pen with an automatically retractable refill as described in claim 8, characterized in that: The recessed sidewall is provided with a positioning rib, and the snap-fit ​​end is provided with a positioning groove that cooperates with the positioning rib for positioning.

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