JP2570883Y2 - Writing implement - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a writing instrument in which a valve ball for preventing writing liquid backflow is accommodated in a cylinder.

[0002]

2. Description of the Related Art Some conventional writing implements have an ink backflow prevention mechanism for preventing the ink (writing liquid) inside from flowing back to the tail end when the pen tip is directed upward. .

For example, Japanese Utility Model Publication No. 4-52067 discloses that
A projecting ridge extending in the axial direction is formed in the ballpoint pen, a ball seat is formed at a position on the tail end side thereof, and a valve chamber is formed between the seat and the projecting ridge. Shows a valve ball movably accommodated therein. According to such a writing instrument, at the time of writing, when the pen tip is directed downward, the valve ball abuts on the ridge, thereby preventing the valve ball from coming off to the distal end side. Ink flows out to the pen tip through between the ridges, and when the pen tip is turned up other than when writing, the valve ball sits on the receiving seat to block the flow of ink, Backflow of the ink to the tail end side is prevented.

[0004]

Problems to be Solved by the Invention There is a problem to be solved in the above writing implement as follows.

A) In a state in which the pen tip faces downward, that is, in a state in which the valve ball is locked on the ridge, a sufficient ink flow rate must be ensured toward the pen tip through the periphery of the valve ball. Therefore, the inner diameter of the valve chamber needs to be sufficiently larger than the outer diameter of the valve ball, so that the valve ball moves freely in the valve chamber not only in the writing tool axial direction but also in the radial direction. Because of such useless movement, it takes a long time for the valve ball to fit into the valve seat when the pen tip is turned up suddenly from the downward position, and immediately prevent ink backflow. Is difficult. Further, when the pen tip is directed obliquely upward instead of right above, the valve ball may not be accurately seated on the valve seat, and backflow of the ink may not be properly prevented.

[0006] B) Since the valve ball is locked by the ridge extending in the axial direction, there is little contact between the ball and the ridge. For this reason, it is desired to develop a structure that can more reliably prevent the ball from coming off. In the above structure, the contact area between the ball and the ridge is increased,
That is, when the ridge is increased in size, the ink flow passage between the ridges becomes narrower, and it becomes difficult to supply sufficient ink to the pen tip.

In view of such circumstances, the present invention ensures quick and reliable prevention of ink backflow in a state where the tip is directed upward while ensuring a sufficient flow rate of the writing liquid when the tip is directed downward. It is another object of the present invention to provide a writing instrument that can reliably perform backflow prevention with a simple structure and ensure ink circulation with a simple structure.

[0008]

According to the present invention, there is provided a writing instrument in which a valve chamber is provided in the middle of a writing fluid flow passage, and a valve ball for preventing backflow is accommodated in the valve chamber. The valve section has a deformed cross section that is substantially circumscribed, and a tail portion of the valve chamber is formed over the entire circumference with the valve ball to form a seal portion that prevents the flow of writing liquid, The distal end portion is provided with a restricting portion for restricting the movement of the valve ball in the distal direction by contacting a part of the valve ball in the circumferential direction.

Specifically, the cross-sectional shape of the valve chamber is preferably a substantially regular polygon substantially circumscribing the valve bulb, and the "substantially regular polygon" is not only an accurate regular polygon but also a vertex thereof. May be rounded. In this case, the restricting portion protrudes inward from each side of the substantially regular polygon which is the cross-sectional shape of the valve chamber, and is constituted by a plurality of ridges having end sides substantially parallel to these sides. Such better effects can be obtained.

[0010] Further, it is more preferable that the inner peripheral surface of the seal portion is a curved surface protruding inward.

[0011]

In the writing instrument, when the tip is directed downward, the valve ball in the valve chamber falls toward the tip and stops at a state where it hits the regulating portion (prevents the valve ball from coming off). In this state, the writing liquid is surely applied to the tip of the writing implement through a gap generated due to a difference between the planar shape (circle) of the valve ball and the cross-sectional shape (shape other than the circle) of the valve chamber, and further, a gap between the regulating portion and the valve ball. Supplied. Specifically, when the cross-sectional shape of the valve chamber is a substantially regular polygon, the gaps near the respective vertices become the writing liquid flow passages.

On the other hand, when the tip of the writing instrument is turned upward, the valve ball in the valve chamber falls toward the tail end, and stands still while hitting the seal. Here, the valve chamber has a substantially regular polygonal cross-sectional shape substantially circumscribing the valve bulb,
It regulates the movement of the valve ball in the radial direction of the writing instrument, allows the valve ball to quickly reach the restricting portion along the axial direction, and reliably guides the valve ball to the seal portion even if the writing instrument is slightly inclined. In this state, the writing liquid is prevented from flowing in this portion by the contact between the seal portion and the valve bulb, and the backflow of the writing liquid from the front end side to the tail end side is prevented.

In this case, the cross section of the valve chamber may be substantially regular polygonal, and the restricting portion may be a plurality of ridges projecting from each side of the valve chamber and having end sides substantially parallel to these sides. In this case, the figure surrounded by the edges of these ridges also becomes a substantially regular polygon, and the writing liquid can be reliably circulated through the gap generated by the difference between the shape and the shape of the bulb. In addition, the valve ball can be securely locked by each ridge, and can be prevented from falling off.

Further, if the inner peripheral surface of the seal portion is formed as a curved surface that is convex inward, the convex surfaces of the valve ball and the seal portion are in line contact with each other over the entire circumference (point contact when viewed in cross section). ), The flow of the writing liquid is more reliably prevented.

[0015]

7 and 8 show the essential parts of a writing instrument according to an embodiment of the present invention. Although a ball-point pen is shown in this embodiment, the present invention can be applied to various writing tools which need to prevent writing liquid from flowing back.

The illustrated ball-point pen has an outer cylinder 10, and an inner cylinder 12 is inserted into the outer cylinder 10, and ink (writing liquid) is stored in the inner cylinder 12. Both cylinders 10, 12
Is closed with a tail plug (not shown).
A front tube (tubular body) 14 made of an elastically deformable material such as a synthetic resin is attached to the tip of the.

The outer peripheral surface of the front cylinder 14 is composed of a small-diameter cylindrical portion 16, a large-diameter cylindrical portion 17, and a tapered conical portion 18 in this order from the tail end side. The small-diameter cylindrical portion 16 and the large-diameter cylindrical portion 17 are fitted into the distal end portions of the inner cylinder 12 and the outer cylinder 10, respectively, until the step portion 20 between the outer cylinder 10 and the step portion 18 contacts the distal end surface of the outer cylinder 10. .

As shown in FIG. 1, a large-diameter hole 24 and a small-diameter hole 26 are formed in the center portion of the front cylinder 14 in the axial direction continuously from the front end side. A valve ball 22 made of a steel ball or the like is accommodated. Here, the large-diameter hole 24 has a diameter D larger than the diameter of the valve bulb 22,
The small diameter hole 26 has a diameter d smaller than the diameter of the valve bulb 22.

In the portion of the large-diameter hole 24 adjacent to the small-diameter hole 26, raised portions 28 are formed at four locations in the circumferential direction. The surface of each raised portion 28 (that is, the inner surface of the front cylinder 14)
Are flat surfaces, and the portions surrounded by the ridges 28 are shown in FIG.
The valve chamber 31 has a substantially square cross section as shown in FIG.
The cross-sectional shape of the valve chamber 31 has a substantially square shape substantially circumscribing the valve ball 22, more specifically, a shape in which the dimension a of each of the four sides is slightly larger than the diameter of the valve ball 22 and the four vertices are arcs. Is set.

Further, the tip side portion of each raised portion 28 (FIG. 1)
In the upper part), a ridge (restriction part) 30 protruding further inward than the raised part 28 is formed. Each ridge 3
Numeral 0 has straight ends parallel to the surface of the raised portion 28 (that is, parallel to each side of the substantially regular polygon which is a cross section of the valve chamber 31), and extends in the same direction. The dimension b of a substantially square figure surrounded by the ridges 30, that is, one side of the figure shown in the center of FIG. 2 is set to be smaller than the diameter of the valve bulb 22. Therefore, the valve ball 22 cannot move further to the distal end side by contacting these protrusions 30.

On the other hand, the valve chamber 31 surrounded by each raised portion 28
And a step formed at the boundary between the ink passage and the small-diameter hole 26, the step has an inwardly convex spherical surface over the entire circumference as shown in FIG. of having on the outside of the front barrel 14 to the central point O ₁₎ there is a seal portion 27. The valve ball 22 is inserted into a valve chamber 31 formed between the seal portion 27 and the ridge 30.
Is accommodated so as to be movable in the axial direction, and the valve ball 22 comes into line contact with the seal portion 27 over the entire circumference (point contact as viewed in each cross section), so that the flow of ink at this portion is ensured. It is to be blocked.

In FIGS. 7 and 8, reference numeral 32 denotes a pen tip, and its tail end shaft 34 is fitted to the tip of the large-diameter hole 24.

Next, the operation of the writing instrument will be described.

First, as shown in FIG. 7, when the tip of the writing instrument is turned downward, the valve ball 22 in the valve chamber 31 falls toward the tip, and stands still while hitting the ridge 30. In this state, gaps 29 are formed at the four corners in the valve chamber 31 due to the difference between the cross-sectional shape (substantially regular polygon) and the planar shape (circle) of the valve ball 22 (see FIG. 3). Because of the difference in shape between the square surrounded by the circle and the valve bulb 22, gaps 29 are formed at the four corners.
(See FIG. 2). Accordingly, ink is reliably supplied from the tail end side to the pen tip through these gaps 29.

On the other hand, when the tip of the writing instrument is turned upward, the valve ball 22 in the valve chamber 31 falls toward the tail end, and rests on the seal 27. Here, since the valve chamber 31 has a substantially regular polygonal cross-sectional shape substantially circumscribing the valve ball 22, the valve ball hardly moves in the writing instrument radial direction (that is, in a useless direction) and does not move along the axial direction. The valve ball 22 reaches the seal portion 27 quickly, and even if the writing implement is slightly inclined, the valve ball 22 can be securely accommodated in the seal portion 27. In this state, since the seal portion 27 and the valve ball 22 come into contact with each other over the entire circumference, the flow of the ink is reliably prevented at this portion, and the backflow of the writing liquid from the front end side to the tail end side is prevented. .

As described above, in this writing instrument, the bulb 22
The cross-sectional shape of the valve chamber 31 that accommodates the valve ball 22 is a square shape that almost circumscribes the valve ball 22. By restricting the movement of the valve ball 22 in the writing tool radial direction on its four sides, unnecessary movement of the valve ball 22 is prevented. In this way, it is possible to reliably and easily secure the flow of the ink in the gaps 29 at the four corners while reliably and promptly guiding the ink in the axial direction without causing any trouble.

Further, in this embodiment, as shown in FIG. 6A, the sealing portion 27 at the tail end of the valve chamber 31 has a curved surface that is convex toward the inside of the front cylinder 14 over its entire circumference, that is, Since the curvature center O _{1 of the} curved surface is formed outside the front cylinder 14, the valve ball 22 and the seal portion 27 are formed.
Are in line contact with each other (ie point contact over the entire circumference)
For example, when the seal portion 36 has a curved surface that is concave toward the inside of the front tube 14 as shown in FIG. 3B (that is, when the center of curvature O ₂ is inside the front tube 14; Valve ball 2 compared to Japanese Patent Publication No. Hei 4-52067).
2. Enhance the certainty of contact with (2) (that is, sealability),
The backflow of the writing liquid can be more reliably prevented.

Further, in this embodiment, the ridges 30 are projected from all the ridges 28, and the ends thereof are substantially parallel to the inner surface of the ridges 28, and the figure surrounded by the ridges 30 is also substantially square. A sufficient gap 29 can be secured between the square and the contour (circle) of the bulb, the ink can be circulated, and the projections 30 can reliably prevent the bulb 22 from coming off. .

In the first aspect of the present invention, the restricting portion does not necessarily have to be the ridge 30 as described above.
A simple protrusion may be used as long as the movement of the second member in the direction of the tip can be restricted. However, if the ridge 30 extends in a direction parallel to the writing instrument radial direction as in the above embodiment, it is advantageous in terms of strength, and even if one ridge 30 is broken, the other ridge 30 is broken. This has the advantage that the retaining of the valve ball 22 can be reliably prevented.

In the present invention, the cross-sectional shape of the valve chamber 31 may be any shape other than a circle substantially circumscribing the valve bulb 22, and may be substantially triangular or substantially pentagonal or more substantially polygonal (particularly preferably substantially regular polygonal). Or, it may be an oval shape or the like.

[0031]

As described above, according to the present invention, the cross-sectional shape of the valve chamber accommodating the valve ball for preventing backflow is a modified cross-section (preferably a substantially regular polygon) substantially circumscribing the valve ball. Since the seal portion and the regulating portion are provided on the side and the tail end side, respectively, while regulating the movement of the valve ball in the radial direction of the writing implement on each side of the valve chamber surface, the shape of the valve ball and the valve chamber cross section The writing liquid flow passage can be easily secured by the gap due to the difference from the shape. Therefore, in a state where the tip of the writing implement is directed upward, the valve bulb is allowed to fall along the axial direction to a substantially straight seal portion without performing unnecessary movement, thereby quickly preventing the backflow of the writing liquid. On the other hand, in a state in which the tip of the writing implement is directed downward, the tip of the writing implement passes through the gap between the valve bulb and the valve chamber surface while reliably preventing the valve bulb from coming off by the contact between the valve bulb and the regulating portion. There is an effect that the writing liquid can be surely supplied to the recording medium.

Here, the cross-sectional shape of the valve chamber is a substantially regular polygon, and the restricting portion projects from each side of the substantially regular polygon and has a plurality of ridges having end sides substantially parallel to these sides. According to the configuration described above, the writing liquid can be reliably circulated through the gap created by the difference between the figure (substantially regular polygon) surrounded by these ridges and the shape of the valve bulb, while the projection projected from each side. There is an effect that the valve ball can be securely locked by the ridge and can be prevented from coming off. In particular, since each ridge extends in a direction parallel to the writing instrument radial direction, it is also advantageous in terms of strength,
Even if one ridge is broken, there is an effect that the other ridge can secure the valve ball from falling off.

Further, according to the seal portion having the curved inner surface which is convex inward, the convex surfaces of the valve ball and the seal portion are brought into line contact (ie, point contact over the entire circumference). Thereby, there is an effect that the sealing effect can be further enhanced and the backflow of the writing liquid can be more reliably prevented.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a front tube constituting a writing instrument according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a transverse sectional view showing a state where a valve ball is removed in FIG. 2;

FIG. 5 is a transverse sectional view showing a state where a valve ball is removed in FIG. 3;

FIG. 6A is an enlarged cross-sectional view of a seal portion of the front cylinder, and FIG. 6B is an enlarged cross-sectional view showing an example in which concavities and convexities are reversed in the seal portion.

FIG. 7 is a longitudinal sectional view showing a state in which a pen tip is directed downward in the writing instrument.

FIG. 8 is a longitudinal sectional view showing a state in which a pen tip is directed upward in the writing instrument.

[Explanation of symbols]

 14 front cylinder 22 valve ball 27 seal portion 28 raised portion 30 ridge 31 valve chamber

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-171290 (JP, A) JP-A-6-239088 (JP, A) JP-A-6-239089 (JP, A) 52067 (JP, Y2) (58) Fields investigated (Int. Cl. ⁶ , DB name) B43K 7/02 B43K 7/10

Claims (4)

(57) [Scope of request for utility model registration] 1. A valve chamber is provided in the middle of a writing liquid passage,
In a writing instrument in which a valve ball for preventing backflow is accommodated in the valve chamber, the cross-sectional shape of the valve chamber is an irregular cross-section substantially circumscribing the valve ball. Along with forming a seal portion that blocks the flow of the writing liquid by being in contact with the periphery, the distal end portion of the valve chamber is in contact with a part of the valve ball in the circumferential direction so that the distal end portion of the valve ball is in the distal direction. A writing implement characterized by having a regulation part for regulating movement. 2. The writing implement according to claim 1, wherein the cross-sectional shape of the valve chamber is a substantially regular polygon that substantially circumscribes the valve bulb. 3. The writing instrument according to claim 2, wherein the restricting portion projects inward from each side of a substantially regular polygon that is a cross-sectional shape of the valve chamber, and has a plurality of end sides that are substantially parallel to these sides. A writing implement characterized by comprising ridges. 4. The writing instrument according to claim 1, wherein the inner peripheral surface of the seal portion is a curved surface that is convex toward the inside.