Retractable writing instrument

Abstract

To effectively suppress impact and vibration associated with a writing action.SOLUTION: A retractable writing instrument includes in a shaft cylinder 10, a core 20 having a writing part 21 at its front end, an urging member 30 that urges the core 20 backward, a receiving member 41 that receives the core 20 from a rear side; a rotor 42 provided on a rear side of the receiving member 41 and rotatable and movable with respect to the shaft cylinder 10; and an annular resilient member 43 that faces the rotor 42 and resiliently forwards the receiving member 41 with a force greater than an urging force of the urging member 30, wherein by moving the rotor 42 forward against the urging force of the urging member 30 and engaging it with the shaft cylinder 10, the writing part 21 is protruded and a protruding state is maintained, and the receiving member 41 integrally includes a receiving portion 41a that receives a rear end of the core 20 from behind, and a shaft portion 41b that protrudes rearward from the receiving portion 41a, and the annular resilient member 43 is annularly attached to the shaft portion 41b, and the rotor 42 is fitted to the shaft portion 41b so as to be able to advance and retreat.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a retractable writing instrument in which a writing part is adapted to appear and disappear from the front end of a barrel by a knock operation. [Background technology]

[0002] Conventional inventions of this type include, for example, a retractable writing instrument, as described in Patent Document 1, which includes a barrel containing a writing body that protrudes and retracts from the front end of the barrel, a return spring that urges the writing body rearward, a second spring that receives the writing body from the rear and contracts, and a rotor that fits concavely into the cylindrical part on the retracting side of the writing body and the second spring, and which engages with the barrel when moved forward to maintain the protruding state of the writing body. Patent document 1 states that "the incorporation of a second spring provides a cushioning effect, preventing fatigue from long periods of writing, and also provides benefits such as protecting the tip of the pen by absorbing impacts from drops and the like, and simplifying the structure." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 60-157284 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the above-mentioned conventional technology, there are cases where the cushioning effect of the second spring is not fully exhibited due to misalignment or bending of the writing element. [Means for solving the problem]

[0005] In view of the above problems, the present invention has the following configuration. The pen is provided with a barrel containing a core having a writing part at its front end, a biasing member for biasing the core rearward, a receiving member for receiving the core from the rear, a rotor provided on the rear side of the receiving member and rotatable and movable forward and backward relative to the barrel, and an annular spring member facing the rotor for springing the receiving member forward with a force greater than the biasing force of the spring member, and is configured such that the writing part is protruded and maintained in the protruding state by moving the rotor forward against the biasing force of the spring member and engaging it with the barrel, the receiving member integrally includes a receiving portion that receives the rear end of the core from behind, and a shaft portion that protrudes rearward from the receiving portion, The annular resilient member is attached to the shaft portion in an annular shape, The rotor is The device is formed in a generally cylindrical shape having a large diameter portion and a small diameter portion whose inner circumferential surface is reduced in diameter at the rear end side of the large diameter portion, The shaft portion is fitted thereto so as to be movable forward and backward. And, The shaft portion penetrates the annular resilient member and has an engaging portion, located rearward of the annular resilient member, that engages with an engaged portion provided on the small diameter portion so as to be able to advance and retreat by a predetermined amount. A retractable writing instrument characterized by: [Effects of the Invention]

[0006] Since the present invention is configured as described above, it is possible to effectively suppress the impact and vibration that accompanies the writing operation. [Brief explanation of the drawings]

[0007] [Figure 1] 1A and 1B are full cross-sectional views showing an example of a writing implement according to the present invention, in which FIG. 1A shows a state in which the writing part is retracted, and FIG. 1B shows a state in which the writing part is protruded. [Figure 2] FIG. 2 is a half cross-sectional view showing a rotor unit of the writing instrument. [Figure 3] In the rotor unit, (a) shows a state in which the receiving member is in an initial position, and (b) shows a state in which the receiving member has retracted and is in contact with the rotor. [Figure 4] FIG. [Figure 5] This shows the rotor unit being attached to the shaft cylinder. The shaft cylinder is shown in full cross section, and the rotor unit is shown in side view. DETAILED DESCRIPTION OF THE INVENTION

[0008] This embodiment discloses the following features. The first feature is that the pen comprises, within a barrel, a core having a writing part at its front end, a biasing member that biases the core rearward, a receiving member that receives the core from the rear side, a rotor that is provided on the rear side of the receiving member and is rotatable and can move back and forth relative to the barrel, and an annular resilient member that faces the rotor and biases the receiving member forward with a force greater than the biasing force of the biasing member.The pen is configured such that the writing part is protruded and maintained in its protruding state by moving the rotor forward against the biasing force of the biasing member and engaging it with the barrel, and the receiving member is integrally provided with a receiving portion that receives the rear end of the core from the rear and a shaft that protrudes rearward from this receiving portion, the annular resilient member is attached in a ring shape to the shaft, and the rotor is fitted to the shaft so that it can move back and forth (see Figures 1 to 5).

[0009] As a second feature, the rotor is formed in a generally cylindrical shape having a large diameter portion and a small diameter portion whose inner circumferential surface is reduced in diameter at the rear end side of the large diameter portion, and the large diameter portion covers the periphery of the annular resilient member, while the small diameter portion supports the rear end of the annular resilient member (see Figure 2).

[0010] As a third feature, the shaft portion penetrates the annular resilient member and has an engaging portion located rearward of the annular resilient member that engages with an engaged portion provided on the small diameter portion so as to be able to move back and forth by a predetermined amount (see Figure 2).

[0011] A fourth feature is that the engaged portion is a through-hole, and the outer periphery rearward of the engaging portion is provided with a press-fit portion that is press-fit into the inner periphery of the circular hole and passes through the circular hole, and a loose insertion portion that is circumferentially adjacent to the press-fit portion and passes through the circular hole without contacting the inner periphery of the circular hole (see Figures 2 and 4).

[0012] As a fifth feature, the shaft portion is provided with a sliding contact portion that slides against the rotor in the front-rear direction (see FIG. 2).

[0013] As a sixth feature, the sliding contact portion has a front sliding contact portion located forward of the annular resilient member and a rear sliding contact portion located rearward of the annular resilient member (see FIG. 2).

[0014] As a seventh feature, the receiving member is rotatably connected to the rotor (see FIGS. 2 and 4).

[0015] As an eighth feature, the rotor is fitted to the shaft portion so that it can move forward and backward and cannot be separated, and the receiving member, the rotor, and the annular resilient member form an integrated rotor unit (see Figures 2 and 5).

[0016] <Specific embodiment> Next, specific embodiments having the above-mentioned features will be described in detail with reference to the drawings.

[0017] In this specification, the barrel axis direction means the direction in which the center line of the barrel extends, and the barrel circumferential direction means the direction around the center line of the barrel. Furthermore, "front" means one side of the barrel axis direction in which the writing part protrudes, and "rear" means the opposite side. In addition, in this specification, the radial direction of the barrel means the diameter direction of the barrel that is perpendicular to the center line of the barrel, the outer radial direction of the barrel means the direction away from the center of the barrel along the radial direction of the barrel, and the inner radial direction of the barrel means the direction toward the center of the barrel along the radial direction of the barrel. Furthermore, in this specification, the core radial direction means the diameter direction of the core that is perpendicular to the center line of the core, the core radial outward direction means the direction away from the core center along the core radial direction, and the core radial inward direction means the direction toward the core center along the core radial direction.

[0018] This retractable writing instrument A comprises a barrel 10, a core 20 housed within the barrel 10 and having a writing portion 21 at its front end, a biasing member 30 that biases the core 20 rearward within the barrel 10, a rotor unit 40 that receives the core 20 from the rear side within the barrel 10, and a knock body 50 that can be engaged with and disengaged from the rotor unit 40 from the rear and whose rear end protrudes from within the barrel 10 to the outside of the barrel 10; the rotor 42 of the rotor unit 40 is advanced against the biasing force of the biasing member 30 and engaged with the inner surface of the barrel 10, causing the writing portion 21 to protrude from the front end of the barrel 10 and maintaining that protruding state.

[0019] The barrel 10 is formed into a long, cylindrical shape extending in the front-to-rear direction from one or more cylindrical members. The barrel 10 in the illustrated example is formed into a long, approximately cylindrical shape from a tapered, cylindrical nose portion 11, a cylindrical front axle 12 that is threadably connected to the front end of the nose portion 11, and a cylindrical rear axle 13 that is threadably connected to the front end of the front axle 12. In the figure, reference numeral 14 denotes a cylindrical elastic grip fitted to the outer periphery of the front axle 12, and reference numeral 15 denotes a clip that opens and closes at the rear end of the rear axle 13.

[0020] An annular step 11a, which is tapered forward, is provided on the inner circumferential surface of the tip 11 in order to lock the front end of the biasing member 30 thereon.

[0021] The rear end side of the inner circumferential surface of the rear axle 13 is provided with a slide groove 13a that allows the rotor 42 to move back and forth without rotating, a cam slope and a locking surface (not shown) that rotates and locks the rotor 42 when it moves forward, and the like. These configurations can be applied to the structure described in JP 2018-149787 A, for example.

[0022] In addition, on the inner surface of the rear axle 13, a climbing-over fitting protrusion 13b is provided forward of the slide groove 13a and the cam slope, etc., for climbing over and fitting the rotor unit 40 rearward during assembly work (see Figure 5). A plurality of these overriding fitting projections 13b are provided at intervals in the circumferential direction of the barrel. Each of the overriding fitting projections 13b is a projection having a generally mountain-shaped vertical cross section.

[0023] According to the illustrated example, the core 20 is a refill for a ballpoint pen, and a writing part 21, which is a ballpoint pen tip, is connected to the front end of an ink tank 22 that is a long cylindrical shape. Other examples of the core 20 include a refill for a mechanical pencil, a refill for an input pen (stylus pen) for electronic devices, and the like. A step 23 that decreases in diameter toward the front is provided on the front end side of the outer circumferential surface of the core 20. The step 23 abuts against the rear end of the biasing member 30 and receives the rearward biasing force (resilient force) of the biasing member 30.

[0024] According to the illustrated example, the biasing member 30 is an annular resilient member, the front end of which abuts against the step 11a in the shaft tube 10 and the rear end of which abuts against the step 23 with the core 20, thereby biasing the core 20 and the rotor unit 40 backward. As another example of the biasing member 30, a tension coil spring that pulls the core 20 rearward can also be used.

[0025] The rotor unit 40 is integrally formed by including a receiving member 41 that receives the core 20 from the rear side, a rotor 42 that is provided on the rear side of the receiving member 41 and is movable forward and backward relative to the shaft tube 10 and rotatable, and an annular resilient member 43 that faces the rotor 42 and resiliently urges the receiving member 41 forward with a force greater than the urging force of the urging member 30. When the rotor unit 40 advances against the biasing force of the biasing member 30, it engages with the inner surface of the barrel 10, thereby maintaining the writing part 21 in a protruding state.

[0026] The receiving member 41 is connected to the rotor 42 so as to be able to move back and forth by a predetermined distance and to be able to rotate freely. This receiving member 41 has a thin-walled cylindrical receiving portion 41a that receives the rear end of the core 20 from behind, a shaft portion 41b that protrudes rearward from the center of the rear end face of this receiving portion 41a, and a plurality of protrusions 41c that protrude rearward from the rear end face of the receiving portion 41a around the shaft portion 41b.

[0027] The shaft portion 41b is formed in the shape of an elongated shaft that penetrates the annular resilient member 43, and has a front sliding contact portion 41b1 and a rear sliding contact portion 41b31 (engagement portions) on its outer circumferential surface that come into sliding contact with the rotor 42 in the front-rear direction.

[0028] The front sliding contact portion 41b1 is a cylindrical surface located in front of the annular resilient member 43 (on the left side in FIG. 2), and its length in the front-to-rear direction is appropriately set so as to move the rotor 42 forward and backward by a predetermined amount.

[0029] The shaft portion 41b has a smaller diameter behind the front sliding contact portion 41b1 via a step portion 41b2. The step portion 41b2 receives the front end portion of the annular resilient member 43.

[0030] A small diameter portion 41b3 of the shaft portion 41b, which is rearward of the stepped portion 41b2, is inserted into the annular resilient member 43. A rear sliding contact portion 41b31 that comes into sliding contact with the engaged portion 42b1 of the rotor 42 in the front-rear direction is provided on the small diameter portion 41b3, rearward of the annular resilient member 43.

[0031] The rear sliding contact portion 41b31 is a recess formed by recessing the outer peripheral surface of the small diameter portion 41b3 in an annular shape over the entire circumference. The bottom surface of this annular recess is formed in a cylindrical shape. The length of the rear sliding contact portion 41b31 in the front-rear direction is set so as to move the rotor 42 forward and backward by a predetermined amount, and the rear sliding contact portion 41b31 functions as an engaging portion that engages with the engaged portion 42b1 of the rotor 42 so as to be able to move forward and backward by a predetermined amount.

[0032] The shaft 41b has a press-fit portion 41b32 on the outer periphery rearward of the rear sliding portion 41b31 (engaging portion) that is press-fitted into the inner circumferential surface of the engaged portion 42b1 (circular hole) and protrudes radially outward in an arc shape so as to pass through the engaged portion 42b1. Furthermore, the shaft 41b has a portion circumferentially adjacent to the press-fit portion 41b32 that is a flat loose insertion portion 41b33 that passes through the engaged portion 42b1 without coming into contact with the inner circumferential surface of the engaged portion 42b1 (circular hole).

[0033] The two press-fit portions 41b32 are provided symmetrically with the central axis therebetween. The outer diameter of these press-fit portions 41b32, 41b32 is slightly larger than the inner diameter of the engaged portion 42b1. Two loosely inserted portions 41b33 are provided substantially parallel to each other with a central axis therebetween. The press-fit portion 41b32 and the loose-insertion portion 41b33 may be one, three or more, or may have a different shape but have the same function.

[0034] The protrusions 41c protrude rearward from the rear end surface of the receiving portion 41a, and are provided at intervals in the circumferential direction. These protrusions 41c come into contact with the front end surface of the rotor 42 when the receiving member 41 moves back toward the rotor 42 (see FIG. 3).

[0035] The rotor 42 is fitted to the shaft portion 41b so as to be movable forward and backward and not to separate from the shaft portion 41b. The rotor 42 is formed in a substantially cylindrical shape and has a large diameter portion 42a and a small diameter portion 42b whose inner and outer circumferential surfaces are reduced in diameter at the rear end side of the large diameter portion 42a.

[0036] The large diameter portion 42a is formed in a cylindrical shape that covers the periphery of the annular resilient member 43 from the front sliding contact portion 41b1. When the receiving member 41 moves back and forth relative to the rotor 42, the front end side of the inner peripheral surface of this large diameter portion 42a comes into sliding contact with the outer peripheral surface of the front sliding contact portion 41b1.

[0037] The small diameter portion 42b is formed in a generally cylindrical shape with an inner diameter smaller than the outer diameter of the annular resilient member 43. An engaged portion 42b1 that protrudes annularly inward in the radial direction is provided on the rear end side of the small diameter portion 42b. The inner peripheral surface of the engaged portion 42b1 is a circular through-hole. The engaged portion 42b1 is set to have a length in the front-rear direction shorter than the recessed portion that constitutes the rear sliding contact portion 41b31 so as to slide against the rear sliding contact portion 41b31 (engagement portion) and move forward and backward by a predetermined amount.

[0038] In addition, on the outer periphery of the rotor 42, there are provided a protrusion 42c extending in the front-to-rear direction so as to fit into the slide groove 13a of the barrel 10 and be guided back and forth, and a cam slope 42d provided at the rear end of this protrusion 42c and in sliding contact with the cam slope 51 of the knock body 50 and the above-mentioned cam slope (not shown) of the barrel 10.

[0039] The annular resilient member 43 is housed in the cylindrical space between the shaft portion 41b and the rotor 42, with its front end abutting against the step portion 41b2 and its rear end abutting against the front end face of the small diameter portion 42b, thereby facing the rotor 42 and resilienting the receiving member 41 forward. The annular resilient member 43 in the illustrated example is a compression coil spring. The biasing force (resilience) of the annular resilient member 43 is greater than the biasing force of the biasing member 30. As another example of the annular resilient member 43, it is possible to use a cylindrical rubber or other resilient material other than a spring.

[0040] The knock body 50 is a rod-shaped member that is knocked from behind. The knock body 50 is formed in a generally cylindrical shape with an open front end face and a closed rear end face, and a cam slope 51 is formed on the front end face for sliding contact with the cam slope 42d of the rotor 42. Furthermore, an engagement protrusion 52 is provided on the outer circumferential surface of the knock body 50, which engages with the slide groove 13a in the barrel 10 and moves forward and backward.

[0041] In the illustrated example, the knock body 50 is composed of two members: a cylindrical member and a member that closes the rear end of the cylindrical member. However, other examples of the knock body 50 include a configuration in which the knock body 50 is made up of a single member, or a configuration in which the knock body 50 is made up of three or more members. In addition, according to the example shown in Figure 1(b), when the writing part 21 is in the protruding state, the knock body 50 can freely move back and forth in the space behind the rotor unit 40, but in other examples, the knock body 50 can also be configured to move forward or backward using a biasing member or the like not shown.

[0042] Next, the characteristic functions and effects of the retractable writing instrument A having the above-described configuration will be described in detail. When the knock body 50 is pushed forward in the initial state (see FIG. 1(a)), the action of the engagement protrusion 52 of the knock body 50, the slide groove 13a in the barrel 10, the cam slope and locking surface (not shown), the protrusion 42c of the rotor 42, the cam slope 42d, etc. causes the core 20 to move forward a predetermined distance, and the writing part 21 is held in a state protruding from the front end of the barrel 10 (see FIG. 1(b)). These actions are substantially the same as those of the structure described, for example, in JP 2018-149787 A. The mechanism for moving the rotor unit 40 forward by a predetermined distance and locking it by external operation can be replaced with a mechanism other than the above-described one.

[0043] When the barrel 10 is held by a writer or the like and writing is performed with the writing part 21 in the protruding state shown in FIG. 1(b), the annular resilient member 43 absorbs vibrations and shocks during the writing action. More specifically, since the rear end of the core 20 is supported by the front end surface of the receiving member 41, when the writing part 21 is pressed against a surface to be written on (such as a piece of paper) and a rearward pressing force greater than the biasing force of the biasing member 30 is applied to the writing part 21, the core 20 and the receiving member 41 move backward against the biasing force of the annular biasing member 43. In other words, the dimension W (see Figures 2 and 3) between the rear end of the protrusion 41c of the receiving member 41 and the front end of the rotor 42 becomes smaller.

[0044] Thereafter, when the pressing force is released, the core 20 and the receiving member 41 move forward due to the resilient force of the annular resilient member 43. That is, due to this forward movement, the dimension W between the rear end of the protrusion 41c of the receiving member 41 and the front end of the rotor 42 increases.

[0045] Therefore, even if vibrations occur in the axial direction of the barrel, for example, due to repeated pressing and releasing of the writing part 21 against the surface being written on while writing, the vibrations can be absorbed by the elasticity of the annular resilient member 43, which expands and contracts within the cylindrical space around the barrel 41b. Moreover, during the vibration, the receiving member 41 moves smoothly back and forth without rattle, with the front sliding contact portion 41b1 and the rear sliding contact portion 41b31 in sliding contact with the rotor 42. In addition, the receiving member 41 is rotatable relative to the rotor 42. Therefore, with the retractable writing instrument A, the transmission of vibrations and impacts of the core 20 to the barrel 10 during writing can be effectively suppressed without being affected by misalignment or bending of the core, thereby providing the writer with a soft writing feel.

[0046] Next, the effects of manufacturing the retractable writing instrument A will be described. As shown in FIG. 4, when assembling the rotor unit 40, an annular resilient member 43 is attached in an annular shape to the shaft portion 41b of the receiving member 41, and the rotor 42 is attached so as to cover the shaft portion 41b and the annular resilient member 43. More specifically, the shaft portion 41b has a press-fit portion 41b32 and a loosely inserted portion 41b33 on the front end side that protrude rearward beyond the annular resilient member 43, and is press-fitted into and penetrates the circular hole-shaped engaged portion 42b1. At this time, the arc-shaped press-fit portion 41b32 slides against the inner peripheral surface of the engaged portion 42b1, but the flat loose-insertion portion 41b33 does not contact the inner peripheral surface of the engaged portion 42b1, so the press-fit force can be made relatively small, resulting in good assembly ease. After the press-fit portion 41b32 passes rearward through the engaged portion 42b1, the rear end of the press-fit portion 41b32 is locked in the front end of the circular hole-shaped engaged portion 42b1, preventing the shaft portion 41b from coming out of the engaged portion 42b1. In other words, the rotor 42 can move forward and backward relative to the receiving member 41 but cannot be separated from it. Therefore, the receiving member 41, the rotor 42 and the annular resilient member 43 can be treated as an integrated rotor unit 40.

[0047] As shown in FIG. 5, the rotor unit 40 having the above configuration is inserted onto the front shaft 12 from the front side, climbs over the over-riding fitting protrusion 13b, and moves behind the over-riding fitting protrusion 13b. In more detail, the annular flange portion 42e on the front end side of the rotor 42 is positioned rearward of the over-riding fitting protrusion 13b, so that the entire rotor unit 40 including the rotor 42 does not move forward of the over-riding fitting protrusion 13b. Therefore, even when the rear axle 13 is removed from the front axle 12 and the core 20 is pulled out to replace the core 20, the rotor unit 40 can be prevented from falling off the rear axle 13.

[0048] According to the above embodiment, as a particularly preferred embodiment, the receiving member 41 is engaged with the rotor 42 so as not to be pulled out. However, as another example, it is also possible to omit the press-fit portion 41b32 that protrudes radially outward, and to adopt a structure in which the rotor 42 and the receiving member 41 are separated in the axial direction.

[0049] Furthermore, the present invention is not limited to the above-described embodiments, and can be modified as appropriate within the scope of the present invention. [Explanation of symbols]

[0050] 10: Shaft tube 13b: Overcoming fitting protrusion 20: Core 21:Writing Department 30: biasing member 40: Rotor unit 41: Support member 41a: Receiving part 41b: Shaft part 41b1: Front sliding contact part 41b31: Rear sliding contact part (engaging part) 41b32: Press-fit part 41b33: Loose insertion part 42: Rotor 42a: Large diameter section 42b: Small diameter part 42b1: Engaged portion (circular hole) 43: Ring-shaped elastic member A:Writing implements

Claims

1. The pen is provided with a core having a writing portion at its front end within a barrel, a biasing member which biases the core rearward, a receiving member which receives the core from the rear side, a rotor which is provided on the rear side of the receiving member and which can move forward and backward with respect to the barrel and rotate, and an annular resilient member which faces the rotor and resilient the receiving member forward with a force greater than the biasing force of the biasing member, and is configured such that the writing portion is protruded and maintained in the protruding state by advancing the rotor against the biasing force of the biasing member and engaging it with the barrel, the receiving member is integrally provided with a receiving portion for receiving the rear end of the core from behind, and a shaft portion protruding rearward from the receiving portion, The annular resilient member is attached annularly to the shaft portion, The rotor is formed in a generally cylindrical shape having a large diameter portion and a small diameter portion having an inner circumferential surface that is reduced in diameter at a rear end side of the large diameter portion, and is fitted to the shaft portion so as to be movable forward and backward. A retractable writing instrument characterized in that the shaft portion penetrates the annular resilient member and has an engaging portion rearward of the annular resilient member that engages with an engaged portion provided on the small diameter portion to be able to move back and forth a predetermined amount.

2. The engaged portion is a through-hole, The retractable writing instrument as described in claim 1, characterized in that the outer peripheral portion rear of the engagement portion is provided with a press-fit portion that is pressed into the inner surface of the circular hole and passes through the circular hole, and a loose insertion portion that is circumferentially adjacent to the press-fit portion and passes through the circular hole without contacting the inner surface of the circular hole.

3. 2. The retractable writing implement according to claim 1, wherein the shaft portion is provided with a sliding contact portion that slides against the rotor in the front-rear direction.

4. 4. The retractable writing instrument according to claim 3, wherein the sliding portion has a front sliding portion located forward of the annular resilient member and a rear sliding portion located rearward of the annular resilient member.

5. The pen is provided with a core having a writing portion at its front end within a barrel, a biasing member which biases the core rearward, a receiving member which receives the core from the rear side, a rotor which is provided on the rear side of the receiving member and which can move forward and backward with respect to the barrel and rotate, and an annular resilient member which faces the rotor and resilient the receiving member forward with a force greater than the biasing force of the biasing member, and is configured such that the writing portion is protruded and maintained in the protruding state by advancing the rotor against the biasing force of the biasing member and engaging it with the barrel, the receiving member is integrally provided with a receiving portion for receiving the rear end of the core from behind, and a shaft portion protruding rearward from the receiving portion, The annular resilient member is attached annularly to the shaft portion, The rotor is fitted to the shaft portion so as to be movable forward and backward. The shaft portion is provided with a sliding contact portion that is in sliding contact with the rotor in a front-rear direction, A retractable writing instrument, characterized in that the sliding contact portion has a front sliding contact portion located forward of the annular resilient member, and a rear sliding contact portion located rearward of the annular resilient member.

6. The rotor is formed in an approximately cylindrical shape having a large diameter portion and a small diameter portion whose inner circumferential surface is narrowed at the rear end side of the large diameter portion, the large diameter portion covering the periphery of the annular resilient member, and the small diameter portion receiving the rear end of the annular resilient member.

7. 6. The retractable writing instrument according to claim 1, wherein the receiving member is rotatably connected to the rotor.

8. A retractable writing instrument as described in any one of claims 1 to 5, characterized in that the rotor is capable of advancing and retracting relative to the shaft portion and is fitted so as not to separate, and the receiving member, the rotor, and the annular resilient member form an integrated rotor unit.

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