JP7219600B2 - Mechanical pencil unit and retractable writing instrument - Google Patents

Description

The present invention relates to a mechanical pencil unit constituting a refill for a mechanical pencil, a mechanical pencil, etc., and a retractable writing instrument equipped with the mechanical pencil unit.

Conventionally, in relation to this type of invention, for example, in Patent Document 1, there is disclosed a holding cylinder, a holding cylinder inserted through a front opening of the holding cylinder, projecting forward from the front end of the holding cylinder, and being able to move forward and backward relative to the holding cylinder. A holder that is supported, a lead lead feeding mechanism that advances the lead core that is inserted into the holder, and a movement direction change that moves the holder forward relative to the holding cylinder and the lead core by the radial force applied from the lead core to the holder. A mechanical pencil unit with a mechanism is described. Then, it is possible to construct a retractable writing instrument by housing this mechanical pencil unit in the barrel.
According to this retractable writing instrument, the mechanical pencil unit is advanced by a predetermined operation, and in a state in which the holder at the front end of the mechanical pencil unit protrudes from the opening at the front end of the barrel, the lead core protruding from the holder is radially moved. When the force is applied, the holder advances relative to the holding cylinder and the lead core, so that the lead core can be covered and protected by the holder.
Further, by moving the lead tank portion on the rear end side toward and away from the holding cylinder by a predetermined operation, the lead lead feeding mechanism can be operated and the lead lead can be fed.

JP 2017-159579 A

However, according to the above-described prior art, there is a possibility that the advancing and retracting lead tank portion may be scraped or worn at the engaging portion with the holding cylinder. In particular, when the lead tank portion rattles in the radial direction with respect to the holding cylinder, scraping and abrasion of the engaging portion become significant.

In view of such problems, the present invention comprises the following configurations.
In a mechanical pencil unit in which a lead tank inserted into the rear end side of a holding cylinder advances and retracts to feed out a lead lead, the rear end of the holding cylinder is engaged with an annular ring protruding radially inward. A first sliding contact portion is provided on the outer peripheral portion of the lead tank portion and is in sliding contact with the inner peripheral surface of the holding cylinder on the front side of the engaging portion. A recess that is cylindrically recessed radially inward on the rear side , and an insertion tube portion that is wider than the bottom surface of the recess on the rear side of the recess , and the recess is the tip end of the engaging portion. A mechanical pencil unit, wherein a bottom portion is disposed radially inwardly of the lead tank portion, and the length of the lead tank portion is equal to or longer than a stroke of advancing and retracting.

Since the present invention is configured as described above, it is possible to prevent shaving, wear, and the like of the lead tank portion.

1 is a cross-sectional view showing an example of a mechanical pencil unit according to the present invention; FIG. 3A to 3C are cross-sectional views sequentially showing states in which the lead tank portion is advanced in the same mechanical pencil unit. FIG. 2 is a cross-sectional view taken along line (III)-(III) in FIG. 1; FIG. 4 is a cross-sectional view showing a wick tank guide member; It is an internal structure diagram showing an example of a writing instrument equipped with the same mechanical pencil unit.

The present embodiment discloses the following features.
A first feature is a mechanical pencil unit in which a lead tank portion inserted through the rear end side of a holding cylinder advances and retracts to feed out a lead lead, in which the rear end of the holding cylinder protrudes radially inward. A first sliding contact portion is provided on the outer peripheral portion of the lead tank portion and is in sliding contact with the inner peripheral surface of the holding cylinder on the front side of the engaging portion. A concave portion is provided on the rear side of the sliding contact portion and is cylindrically recessed radially inward. It is formed to have a length longer than the forward/backward stroke (see FIGS. 1 to 3).

A second feature is that the depth of the recess is approximately equal to the amount by which the engaging portion protrudes from the inner surface of the holding cylinder, in order to prevent the bottom surface of the recess from being scraped or worn even if rattling occurs in the radial direction. It was set to equal or greater than equal (see Figure 2).

As a third feature, in order to effectively prevent rattling in the radial direction, a lead core feeding mechanism for feeding forward the clamped lead core is provided in the holding cylinder. A second sliding contact portion is provided on the front side of the first sliding contact portion and is annularly fitted to the outer peripheral surface of the rear end side of the lead lead feeding mechanism so as to slide back and forth (see FIGS. 1 and 2). ).

As a fourth feature, the lead lead feeding mechanism includes a chuck portion that clamps the lead lead, and a support cylinder portion that supports the rear end side of the chuck portion. The second sliding contact portion of the lead tank portion is provided on the outer peripheral surface of the support cylinder portion. (see Figures 1 and 2).

As a fifth feature, in order to prevent damage to the return core, the support cylinder portion includes a chuck support member connected to the rear end side of the chuck portion, and an inner portion of the chuck support member behind the chuck portion. and a wick tank guide member fitted to the peripheral surface, and the wick tank guide member has a chamfered portion whose diameter increases forward on the front end side of the inner peripheral surface of the wick tank guide member (see FIG. 4).
It should be noted that this fifth feature can be an independent invention that does not partially include the above-described first to fourth features, and in this case also has the effect of preventing damage to the return lead.

The sixth feature is that the mechanical pencil unit is provided to constitute a retractable writing instrument (see FIG. 5).

<Specific embodiment>
Next, specific embodiments having the above characteristics will be described in detail with reference to the drawings. In this specification, the axial direction means the direction in which the center line of the holding cylinder 10 extends. Further, "front" means one side in the axial direction and the direction in which the lead core is drawn out. Also, "rear" means the side opposite to the one side.

The mechanical pencil unit 1 shown in FIG. 1 includes a holding barrel 10, a lead lead feeding mechanism M1 supported in the holding barrel 10, a lead tank portion 60 penetrating through the rear end side of the holding barrel 10, and a motion direction changing mechanism M2 for advancing the holder 20 relative to the lead core x by a radial force component applied to the lead core x.

According to the illustrated example, the holding tube 10 is concentrically connected to the first tube portion 11, which is internal so that the holder 20 protrudes forward, and the rear end side of the first tube portion 11. The second tubular portion 12 and the third tubular portion 13 concentrically connected to the rear end side of the second tubular portion 12 are integrally tubular. A part or all of these cylindrical portions 11, 12, 13 can be integrated.

In particular, the third cylindrical portion 13 is formed in a long cylindrical shape from a hard metal material, and has an engaging portion 13a protruding radially inward at its rear end. As shown in FIG. 3, the engaging portion 13a is formed in an annular shape over the entire circumference, and its inward protruding edge is disposed in a space inside a recessed portion 61b of the lead tank portion 60, which will be described later.

The lead lead feeding mechanism M1 includes a lead breaker 30 that is held in the holding cylinder 10 and is elastically and loosely pressed against the outer peripheral surface of the lead core x, a chuck part 40 that advances and retreats behind the lead breaker 30, It includes a clutch ring 41 annularly fitted to the chuck portion 40 , a substantially cylindrical clutch receiver 42 that receives the clutch ring 41 from the rear side, and a support cylinder portion 43 that supports the rear end side of the chuck portion 40 .
The lead lead feeding mechanism M1 feeds out the lead core x held by the chuck part 40 in accordance with the advancing and retreating motion of the support cylinder part 43 transmitted from the lead tank part 60 . In addition, the lead feeding mechanism M1 moves the lead x, the chuck 40, the support cylinder 43, etc. together with the lead x when an urging force stronger than a preset writing pressure is applied to the lead x clamped by the chuck 40. retreat.

The core breaker 30 is formed in a substantially cylindrical shape from an elastic material such as elastomer resin or synthetic rubber, and its inner peripheral surface is in loose pressure contact with the outer peripheral surface of the lead core x.

The chuck portion 40 is formed by integrally connecting a plurality of long pieces arranged at intervals in the circumferential direction at the rear end side, and elastically deflecting the plurality of long pieces radially inward. At this time, the lead core x is held between the claws on the front end side of these elongated pieces.

The clutch ring 41 is engaged with the clamped chuck portion 40, and when moved forward together with the chuck portion 40, the clutch ring 41 comes into contact with the stepped portion on the inner surface of the holding cylinder 10 and comes off the chuck portion 40, thereby releasing the front end side of the chuck portion 40. . As the chuck portion 40 and the clutch ring 41, those having known structures can be used.

The clutch receiver 42 is provided so as to move back and forth within the holding cylinder 10 by a predetermined amount.

A first biasing member 51 , a second biasing member 52 and a third biasing member 53 are provided inside, outside and behind the clutch receiver 42 .

The first biasing member 51 faces the lead tank portion 60 and biases the clutch receiver 42 forward with a biasing force stronger than a preset normal writing pressure.

The second biasing member 52 is a compression coil spring whose biasing force is greater than that of the holder biasing member 23, which will be described later. It stops and springs between these members. The biasing force of the second biasing member 52 is set to be greater than the resistance force in the advancing/retreating direction due to friction or the like between the core breaker 30 and the lead core x.

The third biasing member 53 is a compression coil spring whose front end side is locked to the clutch receiver 42 and whose rear end side is locked to the support cylinder portion 43, and biases the chuck portion 40 rearward.

The support cylinder portion 43 includes a chuck support member 43a connected to the rear end of the chuck portion 40, and a core tank guide fitted to the inner peripheral surface of the chuck support member 43a behind the rear end of the chuck portion 40. It is integrally provided with the member 43b.

The chuck support member 43a is annularly fitted to the rear end side of the chuck portion 40 and receives the rear end of the third biasing member 53 by its front end portion.

The lead tank guide member 43b has a cylindrical fitting portion 43b1 which is inserted into and fitted to the chuck supporting member 43a, and a rear side of the fitting cylindrical portion 43b1 which is enlarged in diameter to abut on the rear end of the chuck supporting member 43a. It integrally has a flange portion 43b2 and a guide tube portion 43b3 projecting rearward from the flange portion 43b2 (see FIGS. 1 and 4).

The fitting cylinder portion 43b1 is formed in a substantially cylindrical shape having the same inner diameter as the rear end side of the chuck portion 40, and has a chamfered portion 43b11 that expands in diameter toward the front at the front inner edge of the inner peripheral surface.
The chamfered portion 43b11 reduces friction and catching on the lead core x sliding backward when the lead tank portion 60 is pushed forward and the lead core x is pushed backward. prevent damage to x.
Although the chamfered portion 43b11 is C-chamfered in the example of FIG. 4, it may be R-chamfered or an inclined surface of another shape.

The guide tube portion 43b3 is formed in a cylindrical shape extending rearward.
This guide tube portion 43b3 is inserted into the front end side of the lead tank portion 60, and when the lead tank portion 60 advances and retreats, the guide tube portion 43b3 is attached to the inner peripheral surface (second sliding contact portion 61c) of the front end side of the lead tank portion 60. Sliding contact.

The lead tank part 60 has a substantially cylindrical shape with an open front end, and supplies the lead core x from the rear side to the lead lead feeding mechanism M1. The illustrated lead tank portion 60 includes a sliding cylinder portion 61 inserted into the rear end side of the holding cylinder 10 so as to be able to move forward and backward, and a cylindrical tank connected to the sliding cylinder portion 61 and extending rearward. It is composed of a body portion 62 .
It should be noted that the lead tank portion 60 can be configured by a single tubular member as another example other than the illustrated example.

The sliding tubular portion 61 is formed in a substantially cylindrical shape that is inserted into the engaging portion 13a of the third tubular portion 13 and extends in the front-rear direction.
A first sliding contact portion 61a that slides on the inner peripheral surface of the holding cylinder 10 and a cylindrical sliding portion 61a extending radially inward on the rear side of the first sliding contact portion 61a is formed on the outer peripheral portion of the sliding cylindrical portion 61. A concave recess 61b is provided.
A second sliding contact portion 61 c is provided on the front end side of the inner peripheral portion of the sliding cylinder portion 61 .

The first sliding contact portion 61 a is a cylindrical surface that is in sliding contact with the inner peripheral surface of the third cylindrical portion 13 on the front side of the engaging portion 13 a of the holding cylinder 10 .

The concave portion 61 b has a cylindrical bottom portion arranged radially inwardly of the tip of the engaging portion 13 a of the third cylindrical portion 13 , and its length in the front-rear direction corresponds to the advancing/retreating stroke of the lead tank portion 60 . are set accordingly.
In more detail, when the lead tank portion 60 is moved back and forth by a knocking operation or the like, the gap w shown in the figure narrows, and the back and forth motion of the lead tank portion 60 is transmitted to the chuck portion 40 and the support cylinder portion 43, thereby feeding out the lead lead. A lead core x is delivered from the mechanism M1.
The length of the concave portion 61b in the front-rear direction is set so as to include the maximum stroke when the lead tank portion 60 advances and retreats by these operations.
The depth of the concave portion 61b is set to be substantially equal to or greater than the radially inward protruding amount of the engaging portion 13a (see FIG. 2).

The second sliding contact portion 61c is annularly fitted to the rear end side outer peripheral surface of the lead tank guide member 43b of the lead lead feeding mechanism M1 on the front side of the first sliding contact portion 61a.
The second sliding contact portion 61c is a cylindrical surface secured on the front side of the front end of the tank body portion 62 on the inner periphery of the sliding cylinder portion 61, and when the lead tank portion 60 advances and retreats, It slides on the outer peripheral surface of the tank guide member 43b.

Further, an insertion cylinder portion 61d having a larger diameter than the bottom surface of the recess 61b is provided behind the recess 61b in the sliding cylinder portion 61. As shown in FIG.
The insertion tube portion 61d is formed in a cylindrical shape, and its outer peripheral surface is set larger than the bottom outer diameter of the recess 61b and smaller than the inner diameter of the engaging portion 13a.
In the assembly work of the mechanical pencil unit 1, the sliding cylinder part 61 is inserted into the third cylinder part 13 from the front side (the left direction side in FIG. 1). Then, the insertion tube portion 61d is inserted through the engaging portion 13a from the front side.

Further, the motion direction conversion mechanism M2 is composed of the first cylindrical portion 11, the holder 20, the holder biasing member 23, and the like, and the force component in the radial direction applied to the holder 20 via the lead core x causes the lead core x to move. to move the holder 20 forward.

The holder 20 is integrally composed of a holder main body portion 21 and a receiving portion 22 connected to the rear side of the holder main body portion 21 and is supported so as to be able to move forward and backward relative to the holding cylinder 10 . Alternatively, these two members can be integrated.

The holder main body 21 is a substantially cylindrical member that is inserted into the holding cylinder 10 and protrudes forward from the front opening 11 a of the holding cylinder 10 . An annular cam slope 21a is provided on the outer peripheral portion of the holder main body 21 so as to increase in diameter toward the front and slidably contact the front opening 11a.

Then, the mechanical pencil unit 1 having the above configuration is incorporated into a multifunctional retractable writing instrument A, as illustrated in FIG.
In the multi-function retractable writing instrument A, by selectively advancing a plurality of pieces a2 and a3, the front end writing part of the refill connected to the advanced piece a2 (or a3) protrudes forward from the front end of the barrel a1. Let Said refill is, according to the illustrated example, a mechanical pencil unit 1 or a ballpoint pen refill 2 .
For example, a piece a2 having a clip a6 with an opening/closing function is operated to advance against the biasing force of a coil spring a4, and the front end writing portion of a mechanical pencil unit 1 (refill) connected to this piece a2 moves toward the shaft tube a1. When the piece a2 protrudes forward from the front end opening of the shaft tube a1, the piece a2 is locked by the locking portion a5 provided in the shaft tube a1, and this projecting state is maintained.
When the clip a6 is moved forward in this projected state, the lead x is drawn out from the front end of the mechanical pencil unit 1. As shown in FIG.
For this multifunctional retractable writing instrument A, for example, the basic structure shown in Japanese Patent Application Laid-Open No. 2014-198439 can be applied.

Next, the characteristic functions and effects of the mechanical pencil unit 1 and the multifunctional retractable writing instrument A configured as described above will be described in detail.
In the projecting state shown in FIG. 5, when the clip a6 is pushed and knocked with a finger or the like, the gap w is narrowed, and in a state where the front end of the lead tank portion 60 is in contact with the rear end of the support cylinder portion 43, the chuck portion 40 and the support cylinder portion 43 are separated. The tubular portion 43 moves back and forth. By this forward and backward motion, the lead core x is drawn forward from the core breaker 30 .

During the forward/backward movement, the engaging portion 13a at the rear end of the third cylindrical portion 13 maintains a gap between it and the bottom surface of the concave portion 61b on the outer peripheral surface of the sliding cylindrical portion 61 (see FIG. 2). For this reason. It is possible to prevent the outer peripheral surface of the sliding cylinder portion 61 from being scraped by the engaging portion 13a.
Moreover, during the advancing and retreating movement, the lead tank portion 60 moves with high linearity due to the two front and rear sliding contact portions of the first sliding contact portion 61a and the second sliding contact portion 61c. Therefore, it is possible to reduce malfunctions caused by rattling, wear of each contact portion, and the like, and improve quality.

When connecting the sliding cylinder portion 61 to the third cylinder portion 13, the sliding cylinder portion 61 is inserted from the front side, and the cylindrical insertion cylinder portion 61d and the concave portion 61b are engaged with each other in an annular manner. It can be inserted through the portion 13a, and the assembling workability is good.

Further, although detailed description is omitted, according to the mechanical pencil unit 1 having the above configuration, when an excessive force component in the radial direction is applied to the lead core x, the motion direction changing mechanism M2 moves the lead core x relative to the lead core x. Then, the holder 20 can be moved forward to protect the lead core x. Further, even when excessive backward pressure is applied to the lead core x, the lead core x can be retracted together with the chuck part 40 and the like to be protected.

<Modification>
According to the above-described embodiment, as a particularly preferable example, the configuration of the concave portion 61b and the like is applied to the mechanical pencil unit 1 having the movement direction conversion mechanism M2, but as another example, the movement direction conversion mechanism M2 can be omitted.

Further, the mechanical pencil unit 1 having the above configuration is configured as a mechanical pencil refill for the multifunctional retractable writing instrument A, but as another example, the mechanical pencil unit 1 is provided in the barrel to configure a single-function mechanical pencil. It is also possible to

Moreover, the present invention is not limited to the embodiments described above, and can be modified as appropriate without changing the gist of the present invention.

1: Mechanical pencil unit 10: Holding cylinder 13a: Engagement part 20: Holder 40: Chuck part 43: Support cylinder part 43a: Chuck support member 43b: Lead tank guide member 60: Lead tank part 61a: First sliding contact part 61b: concave portion 61c: second sliding contact portion x: lead core M1: lead core feeding mechanism M2: motion direction changing mechanism

Claims (6)

In a mechanical pencil unit in which a lead tank portion inserted through the rear end side of a holding cylinder advances and retreats to extend a lead lead,
An annular engaging portion protruding radially inward is provided at the rear end of the holding cylinder,
The outer peripheral portion of the lead tank portion is provided with a first sliding contact portion that is in sliding contact with the inner peripheral surface of the holding cylinder on the front side of the engaging portion, and a radial direction on the rear side of the first sliding contact portion. A concave portion cylindrically recessed inward and an insertion tube portion having a diameter enlarged with respect to the bottom surface of the concave portion on the rear side of the concave portion are provided, and the concave portion is radially inward of the tip of the engaging portion. A mechanical pencil unit characterized in that the bottom portion is arranged in the container, and the lead tank portion is formed to have a length equal to or longer than the forward/backward stroke. 2. The mechanical pencil unit according to claim 1, wherein the depth of said concave portion is set substantially equal to or more than the amount by which said engaging portion protrudes from the inner surface of said holding cylinder. A lead core feeding mechanism for feeding forward the sandwiched lead core is provided in the holding cylinder,
The lead tank portion is provided with a second sliding contact portion that is annularly fitted to the outer peripheral surface of the lead lead feeding mechanism on the rear end side of the first sliding contact portion and that slides back and forth. 3. The mechanical pencil unit according to claim 1 or 2, wherein the mechanical pencil unit comprises: The lead lead feeding mechanism includes a chuck portion that clamps the lead lead, and a support cylinder portion that supports the rear end side of the chuck portion. configured to retract the chuck portion and the support cylinder portion when applied,
4. The mechanical pencil unit according to claim 3, wherein the second sliding contact portion of the lead tank portion is provided on the outer peripheral surface of the support cylinder portion. The support cylindrical portion includes a chuck support member connected to the rear end side of the chuck portion, and a core tank guide member fitted to the inner peripheral surface of the chuck support member on the rear side of the chuck portion,
5. The mechanical pencil unit according to claim 4, wherein the lead tank guide member has a chamfered portion on the front end side of the inner peripheral surface thereof, the diameter of which increases toward the front. A retractable writing instrument comprising the mechanical pencil unit according to any one of claims 1 to 5.

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