Knock-type writing implement

Abstract

To provide a knock-type writing implement capable of reliably suppressing rattle of members caused by vibration during writing.SOLUTION: The knock-type writing implement includes a knock member 9, and a retraction mechanism that allows a pen nib 31 of a writing element 3 to protrude and retract from the front end of a barrel 2 by pressing the knock member 9 forward. The retraction mechanism includes a plurality of cam teeth 61 and cam grooves 62 formed on the inner surface of the barrel 2 and a rotating element 7 having a plurality of protrusions 75 that can alternately engage with the cam teeth 61 or cam grooves 62, a cam member 8 that is connected to the knock member 9 and has a plurality of cam protrusions 83 that rotate the rotating element 7 and a plurality of engaging protrusions 84 that can engage with the cam grooves 62 on the inner surface of the barrel 2 so as to be movable back and forth, and a spring 10 that urges the writing element 3 backward. In the pen nib protruding state, a dot-like outward protrusion 77 formed on the rotating element 7 and a dot-like inward protrusion 88 formed on the cam member 8 are engaged.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a knock-type writing instrument, and more particularly to a knock-type writing instrument equipped with a retraction mechanism that allows the pen tip of a writing element to be freely retracted from the front end of a barrel by pressing a knock member forward. [Background technology]

[0002] In the past, in this type of writing instrument, for example, Patent Document 1 discloses a knock-type thermochromic writing instrument equipped with a retraction mechanism that allows the nib of the writing instrument to be freely retracted and protruded from the front end of the barrel by pressing the clip body (knock member) forward.

[0003] In detail, in the retraction mechanism of the thermochromic writing implement, the clip body has a shaft portion housed in a barrel and extending in the front-rear direction, and the shaft portion and the rotating member are configured to be engaged in the front-rear direction while being rotatable relative to each other and having some play in the front-rear direction. Note that the play in the front-rear direction (amount of movement) is set to a small dimension that allows the protrusions of the rotating member to engage and disengage with the cam teeth of the cam portion.

[0004] This allows the rotating member to be locked by the cam teeth of the cam portion when the pen tip is in the protruding state, preventing the rotating member from moving backward and suppressing the clip body from moving in the forward and backward directions in an inadvertent manner. As a result, when performing a friction operation with the pen tip in the protruding state, even if the vicinity of the clip body is grasped, the clip body will not move inadvertently toward the friction body, allowing for stable friction operation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-217920 Summary of the Invention [Problem to be solved by the invention]

[0006] On the other hand, since the shaft portion of the clip body and the rotating member are engaged in the front-to-back direction with some play in the front-to-back direction, small vibrations that occur when writing may be transmitted to the clip body, causing rattling.

[0007] The present invention is intended to solve the above-mentioned problems of the prior art, and aims to provide a knock-type writing implement that can reliably suppress rattle of the components due to vibrations in the pen tip protruding state, i.e., during writing.

[0008] In the present invention, "front" refers to the pen tip side, and "rear" refers to the opposite side. In the present invention, the pen tip protruding state refers to the state in which the pen tip protrudes outward from the front end of the barrel, and the pen tip retracted state refers to the state in which the pen tip is retracted into the barrel. [Means for solving the problem]

[0009] The present invention provides a pen that includes a barrel, a writing body housed within the barrel so as to be movable in the front-rear direction, a knock member provided on the outer surface of the barrel, and a retraction mechanism that allows the nib of the writing body to protrude and retract from the front end of the barrel by pressing the knock member forward, the retraction mechanism comprising: a plurality of cam teeth and cam grooves formed on the inner surface of the barrel and extending in the front-rear direction and arranged alternately along the circumferential direction; a rotating member that is rotatably arranged behind the writing body and has a plurality of protrusions that can be alternately engaged with the cam teeth or cam grooves; a cam member that is connected to the knock member and has a plurality of cam protrusions that rotate the rotating member and a plurality of engaging protrusions that can be engaged with the cam grooves on the inner surface of the barrel so as to be movable back and forth; and a retraction mechanism that urges the writing body rearward. a spring, wherein the rotating member has a large-diameter cylindrical portion at the front and a small-diameter cylindrical portion that is integrally connected to the rear of the large-diameter cylindrical portion and has an outer diameter smaller than that of the large-diameter cylindrical portion, and a plurality of dot-like outward protrusions are formed on the outer surface of the small-diameter cylindrical portion, and the cam member is a cylinder with at least the front end open, and has a large-diameter front portion at the front and a small-diameter rear portion that is integrally connected to the rear of the front portion and has an outer diameter smaller than that of the front portion, and a plurality of dot-like inward protrusions are formed on the inner surface of the front portion, and the small-diameter cylindrical portion is loosely inserted into the inner surface of the front portion, and when the pen tip is protruded, the dot-like outward protrusions and the dot-like inward protrusions engage with each other, thereby preventing the rotating member and the cam member from slipping out in the forward and backward directions.

[0010] According to the present invention, when the pen tip is extended, the dot-like outward protrusion and the dot-like inward protrusion are engaged with each other, thereby preventing the rotating member and the cam member from coming loose in the forward and backward directions, thereby reliably suppressing rattling of the members due to vibrations when the pen tip is extended, i.e., when writing.

[0011] Preferably, the number of the dot-like outward projections is the same as the number of the ridges, in which case alignment of the rotating member in the rotational direction during assembly is not required, making assembly easy and achieving the effect of reliably suppressing rattle.

[0012] Preferably, the point-like outward protrusions are capable of being flexibly deformed radially inward, so that even if the point-like outward protrusions and the point-like inward protrusions interfere with each other when the small-diameter cylindrical portion is loosely inserted into the inner surface of the front portion, neither protrusion will be damaged, and a stable rattle suppression effect can be obtained after assembly.

[0013] Preferably, the small-diameter cylindrical portion has a slit extending in the front-rear direction and opening in the radial direction in a portion that avoids the point-like outward protrusions. In this case, the point-like outward protrusions can be reliably and easily deflected radially inward, making assembly easier.

[0014] Preferably, the number of the dot-like inward protrusions is twice the number of the dot-like outward protrusions, in which case alignment of the rotational member and the cam member in the rotational direction during assembly is not required, making assembly easier and achieving the effect of reliably suppressing rattle. [Effects of the Invention]

[0015] The knock-type writing implement of the present invention can reliably suppress rattle of the components due to vibrations in the pen tip protruding state, i.e., during writing. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a vertical cross-sectional view showing a pen tip retracted state of a first embodiment of the present invention; [Figure 2] 1 is a vertical cross-sectional view showing a pen tip protruding state according to a first embodiment of the present invention. FIG. [Figure 3] FIG. 2 is an enlarged longitudinal sectional view of a main part of FIG. [Figure 4] FIG. 4 is an enlarged cross-sectional view taken along the line AA in FIG. 3. [Figure 5] FIG. 4 is an enlarged cross-sectional view taken along the line BB in FIG. 3. [Figure 6] FIG. 3 is an enlarged longitudinal sectional view of a main part of FIG. 2. [Figure 7] FIG. 7 is an enlarged cross-sectional view taken along the line CC in FIG. 6. [Figure 8] FIG. 7 is a view taken along the line DD in FIG. 6. [Figure 9] FIG. 2 is an exploded view showing the main components of the retractable mechanism according to the first embodiment of the present invention. [Figure 10] FIG. 1 is a front view of a rear body according to a first embodiment of the present invention. [Figure 11] FIG. 2 is a front view of the rotating member according to the first embodiment of the present invention. [Figure 12] FIG. 2 is a front view of the cam member according to the first embodiment of the present invention. [Figure 13] FIG. 2 is a vertical cross-sectional view of a cam member according to the first embodiment of the present invention. [Figure 14] 1 is a partial vertical cross-sectional view of a knock member according to a first embodiment of the present invention. [Figure 15] 6 is an enlarged cross-sectional view of a main part of FIG. 5, showing an engagement state between an engagement protrusion and a cam groove according to the first embodiment of the present invention. FIG. [Figure 16] 5 is an enlarged cross-sectional view of a main part of FIG. 4, showing an engagement state of a convex portion and a concave portion according to the first embodiment of the present invention. FIG. [Figure 17] 1A and 1B are schematic diagrams illustrating the principle of a retraction mechanism according to a first embodiment of the present invention. [Figure 18] 17(a) to 17(d) and is a vertical cross-sectional view showing the engagement relationship between a rotating member and a cam member in the first embodiment of the present invention. FIG. [Figure 19] FIG. 10 is a front view of a rotary member according to a second embodiment of the present invention. [Figure 20] FIG. 10 is a perspective view of a rotary member according to a second embodiment of the present invention. [Figure 21] FIG. 10 is a vertical cross-sectional view of a cam member according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] First Embodiment A first embodiment of a knock-type writing instrument of the present invention will be described with reference to the drawings (see FIGS. 1 to 18).

[0018] As shown in Figure 1 or Figure 2, the knock-type writing instrument 1 of this embodiment comprises a barrel 2, a writing body 3 housed in the barrel 2, and a retraction mechanism that allows the pen tip 31 of the writing body 3 to freely protrude and retract from the front end hole 41 of the barrel 2.

[0019] The writing element 3 comprises a pen tip 31, an ink reservoir 32 into whose front end opening the pen tip 31 is press-fitted, ink 34 filled in the ink reservoir 32, and a follower 35 (e.g., a high-viscosity fluid) filled at the rear end of the ink 34 and which moves forward as the ink 34 is consumed.

[0020] The pen tip 31 may be, for example, a metal ballpoint pen that rotatably holds a ball at its front end, or a synthetic resin pen tip holder that holds the rear outer surface of the ballpoint pen tip. A tail plug 33 having an air hole that allows ventilation between the ink reservoir 32 and the outside is attached to the rear opening of the ink reservoir 32.

[0021] ·Shaft cylinder As shown in FIG. 1 or 2, the barrel 2 is made up of a front axle 4, an intermediate shaft 5 connected to the rear end of the front axle 4, and a rear axle 6 connected to the rear end of the intermediate shaft 5.

[0022] Front barrel 4 is a tapered cylindrical body made of metal or synthetic resin. A front end hole 41, through which pen tip 31 protrudes and retracts, is formed axially at the front end of front barrel 4. A spring-loaded body holding portion 42 is integrally formed on the inner surface of front barrel 4. The spring-loaded body holding portion 42 is made up of a holding wall portion 42a into which the outer peripheral surface of the front end of spring-loaded body 10 is fitted, and a locking step portion 42b on which the front end of spring-loaded body 10 is locked. A female thread is formed on the inner surface of the rear end opening of front barrel 4.

[0023] The intermediate shaft 5 is a cylindrical body made of synthetic resin with both ends open. A male thread portion is formed on the outer surface of the front end of the intermediate shaft 5 so that it can be threadedly engaged with a female thread portion of the front shaft 4. A male thread portion is formed on the outer surface of the rear end of the intermediate shaft 5 so that it can be threadedly engaged with a female thread portion of the rear shaft 6. A grip portion 51 made of an elastic material is formed on the outer surface of the middle portion of the intermediate shaft 5. The grip portion 51 is provided on the outer surface of the front shaft 4 by two-color molding or by attaching a separate member.

[0024] In this embodiment, the front shaft 4 and the intermediate shaft 5 are attached detachably by screwing together, making it possible to replace the writing body 3. Also, the intermediate shaft 5 and the rear shaft 6 are attached detachably by screwing together, making it possible to replace the writing body 3.

[0025] The rear axle 6 is a cylindrical body made of synthetic resin with both ends open. A female thread is formed on the inner surface of the front end opening of the rear axle 6 so that it can be threadedly engaged with the male thread on the outer surface of the rear end of the intermediate shaft 5. A plurality of (for example, four) cam teeth 61 and cam grooves 62 extending in the front-to-rear direction are integrally formed on the inner surface of the rear part of the rear axle 6.

[0026] As shown in Figure 9, the cam teeth 61 and the cam grooves 62 are arranged alternately in the circumferential direction. Each cam tooth 61 is formed with a cam guide groove 62a extending in the front-rear direction. The cam guide grooves 62a and the cam grooves 62 are arranged alternately at equal intervals in the circumferential direction. A locking wall portion 63 is integrally formed at the rear end of the cam groove 62.

[0027] 3 and 9, a slide hole 64 that opens rearward from the rear end of the rear body 6 and extends in the front-to-rear direction is formed in the side wall of the rear body 6 behind the locking wall portion 63. A single guide groove 65 that extends in the front-to-rear direction is formed on the inner surface of the rear end opening of the rear body 6 on the side opposite to the slide hole 64. The guide groove 65 passes through the locking wall portion 63 and is in communication with the cam groove 62.

[0028] 10, the slide hole 64 has a narrow front hole 64a and a wide rear hole 64b that is connected to the front hole 64a and is open to the rear. A slide groove 66 is formed in front of the slide hole 64, with which the ball portion 91a of the clip 91 can be engaged.

[0029] ·Appearance mechanism The retraction mechanism is a knock-type retraction mechanism using a rotary cam mechanism. The retraction mechanism includes cam teeth 61 and cam grooves 62 formed on the inner surface of the barrel 2 (inner surface of the rear barrel 6), a rotating member 7 that engages with the cam teeth 61 or cam groove 62 and abuts against the rear end of the writing element 3, a cam member 8 that engages with the rotating member 7 and cam groove 62, a knock member 9 connected to the cam member 8, and a spring 10 (e.g., a compression coil spring) that is housed in the barrel 2 and urges the writing element 3 rearward. The retraction mechanism of this embodiment is a double knock type in which the knock member 9 is pressed forward both in the pen tip extension operation and the pen tip retraction operation.

[0030] Rotating parts The rotating member 7 is a cylindrical body made of synthetic resin and open at both ends. As shown in Fig. 11, an annular flange 71 is formed at the front end of the rotating member 7. A large-diameter cylindrical portion 72 is formed behind the annular flange 71 of the rotating member 7. A small-diameter cylindrical portion 73 having an outer diameter smaller than that of the large-diameter cylindrical portion 72 is formed behind the large-diameter cylindrical portion 72 of the rotating member 7.

[0031] A step 74 is formed on the inner surface of the front end of the rotating member 7. The rear end of the writing element 3 (the tail plug 33 attached to the rear end of the writing element 3) comes into contact with the step 74. A plurality of (for example, four) ridges 75 extending in the front-rear direction are formed on the outer surface of the large-diameter cylindrical portion 72 (rear of the annular flange 71 and in front of the small-diameter cylindrical portion 73) and capable of engaging with the cam grooves 62. Cam slopes 76 that can come into contact with the cam teeth 61 and the cam protrusions 83 of the cam member 8 are formed at the rear ends of the ridges 75.

[0032] A plurality of dot-like outward protrusions 77 are formed on the outer surface of the small diameter cylindrical portion 73. The number of dot-like outward protrusions 77 is the same as the number of ridges 75. In this embodiment, the number of dot-like outward protrusions 77 and the number of ridges 75 are each four. The small diameter cylindrical portion 73 is loosely inserted into the inner surface of the front end portion of the cam member 8 (the inner surface of the large diameter front portion 81).

[0033] Cam parts 12 and 13, the cam member 8 is a cylindrical body made of synthetic resin with a bottom and an open front end and a closed rear end. The cam member 8 includes a large-diameter front portion 81 and a small-diameter rear portion 82 (insertion portion) that is integrally connected to the rear of the front portion 81 and has an outer diameter smaller than that of the front portion 81.

[0034] A plurality of (e.g., eight) sawtooth (mountain-shaped) cam protrusions 83 are circumferentially connected to one another on the front end surface of the cam member 8 (the front end surface of the large-diameter front portion 81). A plurality of (e.g., eight) engagement protrusions 84 are formed on the outer surface of the front end portion of the cam member 8 (the outer surface of the front end portion of the large-diameter front portion 81) and dispersed along the circumferential direction. Each engagement protrusion 84 is provided behind a corresponding cam protrusion 83. In the pen tip retracted state, the engagement protrusions 84 are engaged with the engagement wall portion 63 in the front-rear direction. The engagement protrusions 84 and the cam groove 62 are engaged with each other with a rotational play.

[0035] Furthermore, the engagement protrusion 84 and the cam guide groove 62a are engaged with each other with a play in the rotational direction. Specifically, as shown in FIG. 15, there is a difference of 0.19 mm between the width S1 of the cam groove 62 and the width S2 of the engagement protrusion 84. Similarly, there is a difference of 0.19 mm between the width of the cam guide groove 62a and the width of the engagement protrusion 84. This play (S1-S2) is preferably set in the range of 0.16 to 0.25 mm, and more preferably in the range of 0.18 to 0.21 mm. However, this play (0.19 mm) is just an example, and any other value can be used.

[0036] As shown in Figure 13, a plurality of (four in this embodiment) dot-like inward protrusions 88 are formed and dispersed circumferentially on the inner surface of the front end of the cam member 8 (the inner surface of the large-diameter front portion 81). The small-diameter cylindrical portion 73 of the rotating member 7 is loosely inserted into the inner surface of the front end of the cam member 8 (the inner surface of the large-diameter front portion 81). In particular, in the pen tip protruding state, with the small-diameter cylindrical portion 73 loosely inserted into the inner surface of the front portion 81, the dot-like outward protrusions 77 and the dot-like inward protrusions 88 are engaged in the front-rear direction with no play in the front-rear direction. This prevents the rotating member 7 and the cam member 8 from slipping out in the front-rear direction.

[0037] A plurality of (e.g., four) protrusions 85 extending in the front-rear direction are formed at equal intervals along the circumferential direction on the outer surface (outer surface of the base) of the front end of the small-diameter rear portion 82 (insertion portion) of the cam member 8. A first outward protrusion 86 is formed on the outer surface of the small-diameter rear portion 82 (insertion portion) rearward of the protrusions 85. A second outward protrusion 87 is formed on the outer surface of the small-diameter rear portion 82 (insertion portion) rearward of the first outward protrusion 86. The first outward protrusion 86 and the second outward protrusion 87 are formed by annular protrusions or multiple dispersed protrusions. The outer diameter of the first outward protrusion 86 is set larger than the outer diameter of the second outward protrusion 87, thereby allowing the small-diameter rear portion 82 (insertion portion) to be inserted smoothly and easily into the tubular portion 93.

[0038] Knock parts As shown in FIG. 14 , the knock member 9 includes a clip 91 extending in the front-rear direction, a clip base 92 integrally connected to the rear of the clip 91, and a bottomed tubular portion 93 integrally connected to the clip base 92, and is made of synthetic resin. A ball portion 91a protrudes integrally from the inner surface of the clip 91. The clip base 92 includes a plate-shaped first connecting wall portion 92a extending in the front-rear direction and a plate-shaped second connecting wall portion 92b integrally connected to the rear end of the first connecting wall portion 92a and extending perpendicular to the axis. This improves the durability of the clip base 92. The ball portion 91a of the clip 91 is formed in a plate shape extending in the front-rear direction and is engaged with the slide groove 66 on the outer surface of the rear axle 6 so as to be movable in the front-rear direction. This prevents the clip 91 from rotating.

[0039] The clip base 92 can be inserted into the slide hole 64. When the knock member 9 is pressed forward to change from the pen tip retracted state to the pen tip extended state, the first connecting wall 92a is inserted into the narrow front hole 64a of the slide hole 64, and the second connecting wall 92b is inserted into the wide rear hole 64b of the slide hole 64. This further prevents the clip 91 from rotating when the knock member 9 is pressed forward.

[0040] A single guide protrusion 93a is integrally formed on the outer surface of the cylindrical portion 93 on the radially opposite side from the clip base portion 92. A plurality of (e.g., eight) recesses 93b extending in the front-rear direction are formed at equal intervals along the circumferential direction on the inner surface of the front-end opening of the cylindrical portion 93. Each recess 93b opens forward from the front end of the cylindrical portion 93. A first inward protrusion 93c is formed on the inner surface of the cylindrical portion 93 behind the recess 93b. A second inward protrusion 93d is formed on the inner surface of the cylindrical portion 93 behind the first inward protrusion 93c. The first inward protrusion 93c and the second inward protrusion 93d are formed as annular protrusions or multiple dispersed protrusions. The inner diameter of the first inward protrusion 93c is set larger than the inner diameter of the second inward protrusion 93d, allowing the small-diameter rear portion 82 (insertion portion) to be smoothly and easily inserted into the cylindrical portion 93. The rear end surface of the clip 91, the rear end surface of the clip base 92 (second connecting wall portion 92b), and the rear end surface of the cylindrical portion 93 form a pressing operation surface (knock surface) that is flush with one another.

[0041] The small-diameter rear portion 82 (insertion portion) of the cam member 8 is inserted into the cylindrical portion 93, and the inner surface of the cylindrical portion 93 and the outer surface of the small-diameter rear portion 82 are connected by fitting. When the inner surface of the cylindrical portion 93 and the outer surface of the small-diameter rear portion 82 are fitted together, the recessed portion 93b on the inner surface of the cylindrical portion 93 engages with the protruding portion 85 on the outer surface of the small-diameter rear portion 82, the first inward protrusion 93c on the inner surface of the cylindrical portion 93 and the first outward protrusion 86 on the outer surface of the small-diameter rear portion 82 ride over and engage with each other, and the second inward protrusion 93d on the inner surface of the cylindrical portion 93 and the second outward protrusion 87 on the outer surface of the small-diameter rear portion 82 ride over and engage with each other. In addition, an abutting step 81a is formed at the rear end of the large-diameter front portion 81, and the abutting step 81a and the front end of the cylindrical portion 93 abut against each other. The recess 93b and the protrusion 85 are engaged in a non-rotational manner with some play in the rotational direction. The amount of play in the rotational direction between the cam groove 62 and the engagement protrusion 84 is set larger than the amount of play in the rotational direction between the recess 93b and the protrusion 85. Specifically, as shown in FIG. 16 , there is a difference of 0.10 mm between the width dimension T1 of the recess 93b on the inner surface of the cylindrical portion 93 and the width dimension T2 of the protrusion 85 on the outer surface of the small-diameter rear portion 82. That is, in this embodiment, the amount of play in the rotational direction between the cam groove 62 and the engagement protrusion 84 is set larger than the amount of play in the rotational direction between the recess 93b and the protrusion 85.

[0042] Guide protrusion 93a of knock member 9 is engaged so as to be movable in the front-rear direction with guide groove 65 on the inner surface of the rear end opening of rear barrel 6 and cam groove 62 which communicates in the front-rear direction with guide groove 65. In the pen tip retracted state, guide protrusion 93a is engaged with guide groove 65, and in the pen tip extended state, guide protrusion 93a is engaged with cam groove 62.

[0043] Pen tip retraction operation 17(a) and 18(a), in the pen tip retracted state, the engaging projection 84 of the cam member 8 is engaged with the engaging wall portion 63 at the rear end of the cam groove 62, the ridge 75 of the rotating member 7 is engaged with the cam groove 62, and the cam slope 76 at the rear end of the ridge 75 of the rotating member 7 is in contact with the cam projection 83. The writing tool 3 is constantly urged backward by the spring 10.

[0044] Next, as shown in Figures 17(b) and 18(b), when the knock member 9 is pressed forward from the pen tip retracted state against the rearward bias of the spring 10, the protrusion 75 and the engaging protrusion 84 move forward along the cam groove 62, and the protrusion 75 moves forward from the cam groove 62, disengaging from the cam groove 62. At the same time, the cam protrusion 83 comes into contact with the cam slope 76, causing the rotating member 7 to rotate, and the cam slope 76 at the rear end of the protrusion 75 engages with the cam tooth 61, maintaining the pen tip protruding state (see Figures 17(c) and 18(c)).

[0045] As mentioned above, in the case of conventional knock-type writing instruments, the shaft portion of the clip body (corresponding to the cam member 8 in this embodiment) and the rotating member are engaged in the front-to-back direction with some play in the front-to-back direction, so there was a risk that small vibrations generated during writing would be transmitted to the clip body, causing rattling.

[0046] On the other hand, in the case of the knock-type writing instrument 1 of the present invention, particularly in the pen tip protruding state, with the small-diameter cylindrical portion 73 loosely inserted into the inner surface of the front portion 81, the dot-like outward projections 77 and the dot-like inward projections 88 are engaged in the front-rear direction without any play in the front-rear direction, thereby preventing the rotating member 7 and the cam member 8 from slipping out in the front-rear direction. This reliably prevents the members from rattling in the pen tip protruding state, i.e., due to vibrations during writing.

[0047] Furthermore, when the pen tip is not in the protruding state (see Figures 18(a), (b), and (d)), the small-diameter cylindrical portion 73 is loosely inserted into the inner surface of the front portion 81, and the dot-like outward protrusions 77 and the dot-like inward protrusions 88 are not engaged in the front-to-back direction, so the rotating member 7 and the cam member 8 are rotatable relative to each other and have play relative to each other in the front-to-back direction, thereby achieving smooth knocking operation.

[0048] Finally, when the knock member 9 is pressed forward from the pen tip extended state (see FIGS. 17(c) and 18(c)) against the rearward bias of the spring 10, the protrusion 75 and the engaging protrusion 84 move forward, and the cam protrusion 83 comes into contact with the cam slope 76, rotating the rotating member 7 and disengaging the cam slope 76 at the rear end of the protrusion 75 from the cam tooth 61 (see FIGS. 17(d) and 18(d)). When the forward bias of the knock member 9 is subsequently released, the rearward bias of the spring 10 moves the rotating member 7 and cam member 8 rearward, engaging the protrusion 75 with the cam groove 62, and the protrusion 75 moves rearward along the cam groove 62. The engaging protrusion 84 of the cam member 8 then engages with the engaging wall 63 at the rear end of the cam groove 62, resulting in the pen tip retracted state (returning to the state shown in FIGS. 17(a) and 18(a)).

[0049] As described above, the knock-type writing instrument 1 of this embodiment comprises the barrel 2, the writing body 3 housed within the barrel 2 so as to be movable in the front-rear direction, a knock member 9 provided on the outer surface of the barrel 2, and a retraction mechanism that allows the pen tip 31 of the writing body 3 to protrude and retract from the front end of the barrel 2 by pressing the knock member 9 forward. The retraction mechanism comprises a plurality of cam teeth 61 and cam grooves 62 formed on the inner surface of the barrel 2 and extending in the front-rear direction and arranged alternately along the circumferential direction, a rotating member 7 that is rotatably arranged behind the writing body 3 and has a plurality of protrusions 75 that can be alternately engaged with the cam teeth 61 or the cam grooves 62, and a cam member that is connected to the knock member 9 and has a plurality of cam protrusions 83 that rotate the rotating member 7 and a plurality of engaging protrusions 84 that can be engaged with the cam grooves 62 on the inner surface of the barrel 2 so as to be movable back and forth. a spring 10 that urges the writing element 3 rearward, in which the rotating element 7 has a large-diameter cylindrical portion 72 at the front and a small-diameter cylindrical portion 73 that is integrally connected to the rear of the large-diameter cylindrical portion 72 and has an outer diameter smaller than that of the large-diameter cylindrical portion 72, and a plurality of dot-like outward protrusions 77 are formed on the outer surface of the small-diameter cylindrical portion 73, and the cam member 8 is a cylinder with at least the front end open, and has a large-diameter front portion at the front and a small-diameter rear portion that is integrally connected to the rear of the front portion and has an outer diameter smaller than that of the front portion, and a plurality of dot-like inward protrusions 88 are formed on the inner surface of the front portion, and the small-diameter cylindrical portion 73 is loosely inserted into the inner surface of the front portion, and when the pen tip is protruded, the dot-like outward protrusions 77 and the dot-like inward protrusions 88 engage with each other, thereby preventing the rotating element 7 and the cam member 8 from coming off in the front-rear direction.

[0050] In the knock-type writing instrument 1 of this embodiment, when the pen tip is extended, the dot-like outward protrusion 77 engages with the dot-like inward protrusion 88, thereby preventing the rotating member 7 and the cam member 8 from coming loose in the forward and backward directions, thereby reliably suppressing rattling of the members due to vibrations when the pen tip is extended, i.e., when writing.

[0051] Furthermore, the number of dot-like outward projections 77 is the same as the number of ridges 75. In this case, alignment of the rotational direction of the rotating member 7 during assembly is not required, making assembly easy and providing the effect of reliably suppressing rattle.

[0052] <Second embodiment> A second embodiment of the knock-type writing instrument 1 of the present invention will be described with reference to the drawings (see FIGS. 16 to 19).

[0053] This embodiment is a partial modification of the first embodiment. Specifically, slits 73a are provided in the small diameter portion of the rotating member 7 of the first embodiment, allowing the point-like outward protrusions 77 to bend and deform radially inward. The number of point-like inward protrusions 88 of the cam member 8 of the first embodiment is changed from four to eight. This is described in detail below.

[0054] Rotating parts A plurality of dot-like outward protrusions 77 are formed on the outer surface of the small-diameter cylindrical portion 73 of the rotating member 7. The number of dot-like outward protrusions 77 is the same as the number of ridges 75. As shown in Figure 19, the small-diameter cylindrical portion 73 has slits 73a extending in the front-rear direction and opening in the radial direction in a portion thereof avoiding the dot-like outward protrusions 77, and the dot-like outward protrusions 77 are capable of bending and deforming radially inward.

[0055] In addition, the small-diameter cylindrical portion 73 of this embodiment is provided with flexible pieces 73b extending in the axial direction between the slits 73a. The flexible pieces 73b are shaped like long, thin plates, and can be easily bent and deformed in the radial direction. In this embodiment, the number of point-like outward protrusions 77, ridges 75, slits 73a, and flexible pieces 73b is all the same, which is four.

[0056] Cam parts 21, a plurality of (eight in this embodiment) dot-like inward protrusions 88 are formed and dispersed in the circumferential direction on the inner surface of the front end portion (inner surface of the large-diameter front portion 81) of the cam member 8. The small-diameter cylindrical portion 73 of the rotating member 7 is loosely inserted into the inner surface of the front end portion of the cam member 8 (inner surface of the large-diameter front portion 81).

[0057] In particular, in the pen tip protruding state, with the small-diameter cylindrical portion 73 loosely inserted into the inner surface of the front portion 81, the dotted outward projections 77 and the dotted inward projections 88 are engaged in the front-rear direction without any play in the front-rear direction, thereby preventing the rotating member 7 and the cam member 8 from slipping out in the front-rear direction.

[0058] Furthermore, in this embodiment, the number of dot-like inward protrusions 88 is twice the number of dot-like outward protrusions 77. Specifically, since there are eight dot-like inward protrusions 88, when assembling the cam member 8, it can be inserted into the barrel 2 at any angle in the radial direction. This eliminates the need to align the rotational direction of the rotating member 7 and the cam member 8 during assembly, making assembly easier.

[0059] As described above, in the knock-type writing instrument 1 of this embodiment, the dot-like outward protrusions 77 can be flexibly deformed radially inward. In this case, even if the dot-like outward protrusions 77 and the dot-like inward protrusions 88 interfere with each other when the small-diameter cylindrical portion 73 is loosely inserted into the inner surface of the front portion, neither protrusion is damaged, and a stable rattle suppression effect can be achieved after assembly.

[0060] Furthermore, the small-diameter cylindrical portion 73 has a slit 73a extending in the front-rear direction and opening in the radial direction in a portion that avoids the point-like outward protrusion 77. In this case, the point-like outward protrusion 77 can be reliably and easily bent and deformed radially inward, making assembly easier.

[0061] Furthermore, the number of dot-like inward protrusions 88 is twice the number of dot-like outward protrusions 77. In this case, alignment of the rotational direction of the rotating member 7 and the cam member 8 during assembly is not required, making assembly easier and achieving the effect of reliably suppressing rattle.

[0062] The other configurations and effects are the same as those of the first embodiment, and therefore will not be described here. [Explanation of symbols]

[0063] 1. Knock-type writing implement 2 shaft cylinder 3 Cursive 31 Pen Tip 32 Ink reservoir 33 tail plug 34 Ink 35 Follower 4 Front axle 41 Front end hole 42 Projectile holding part 42a Retaining wall 42b Locking step 5 Intermediate shaft 51 Grip section 6 rear axle 61 cam teeth 62 Cam groove 62a Cam guide groove 63 Locking wall 64 slide hole 64a Anterior hole 64b Posterior foramen 65 Guide groove 66 Slide groove 7 Rotating members 71 Annular flange 72 Large diameter cylinder 73 Small diameter cylinder part 73a Slit 73b Flexible piece 74 Step part 75 protrusion 76 Cam slope 77 Punctate extrinsic process 8 Cam member 81 Front 81a Contact stepped part 82 Rear (insertion part) 83 Cam protrusion 84 Engagement protrusion 85 Convex part 86 First outward projection 87 Second outward projection 88 Punctate introvert process 9 Knock parts 91 clips 91a Tamabe 92 Clip base 92a first connecting wall portion 92b Second connecting wall portion 93 Cylindrical part 93a Guide protrusion 93b Recess 93c First inward projection 93d Second inward process 10. Spring body

Claims

1. A shaft cylinder and a writing element housed in the barrel so as to be movable in the front-rear direction; a knock member provided on an outer surface of the barrel; a retraction mechanism that allows the pen tip of the writing element to be freely retracted from the front end of the barrel by pressing the knock member forward, The retractable mechanism is a plurality of cam teeth and cam grooves formed on the inner surface of the barrel, the cam teeth and cam grooves being alternately arranged along the circumferential direction and extending in the front-rear direction; a rotating member rotatably disposed behind the writing body and having a plurality of protrusions that can alternately engage with the cam teeth or the cam grooves; a cam member connected to the knock member, having a plurality of cam protrusions for rotating the rotary member, and having a plurality of engaging protrusions that are engaged with the cam grooves on the inner surface of the barrel so as to be movable back and forth; A knock-type writing instrument having a spring that urges the writing body backward, the rotating member has a large-diameter cylindrical portion at the front and a small-diameter cylindrical portion that is integrally connected to the rear of the large-diameter cylindrical portion and has an outer diameter smaller than that of the large-diameter cylindrical portion, and a plurality of point-like outward protrusions are formed on the outer surface of the small-diameter cylindrical portion; the cam member is a cylindrical body that is open at least at its front end and has a large-diameter front portion at the front and a small-diameter rear portion that is integrally connected to the rear of the front portion and has an outer diameter smaller than that of the front portion, and a plurality of point-like inward protrusions are formed on the inner surface of the front portion; A knock-type writing instrument in which the small-diameter cylindrical portion is loosely inserted into the inner surface of the front portion, and when the pen tip is extended, the dot-like outward protrusion and the dot-like inward protrusion engage with each other, thereby preventing the rotating member and the cam member from slipping out in the forward and backward directions.

2. 2. The knock-type writing implement according to claim 1, wherein the number of the dot-like outward projections is the same as the number of the ridges.

3. 3. The knock-type writing implement according to claim 2, wherein the outwardly directed point-like protrusions are capable of being flexibly deformed radially inward.

4. 4. The knock-type writing implement according to claim 3, wherein the small-diameter cylindrical portion has a slit extending in the front-rear direction and opening in the radial direction at a portion thereof avoiding the point-like outward protrusion.

5. 5. The knock-type writing implement according to claim 4, wherein the number of the inwardly directed dot-like projections is twice the number of the outwardly directed dot-like projections.

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