US2732829A

US2732829A - fehling

Info

Publication number: US2732829A
Authority: US
Priority date: 1948-09-23
Publication date: 1956-01-31
Anticipated expiration: 1973-01-31
Also published as: GB695862A; LU29725A1; FR995969A; DE870814C; CH280522A; BE491286A

Description

Jan. 31, 1956 H. R. FEHLING 2,732,329

INK RESERVQIR TUBE 'Filed sept. 22, 1949 2 Sheets-sheen'v 2 H66. 2 'ff/6.2 2

Attornev:

`to the -usual size of a writing instrument.

INK REsERvoIR TUBE :Hans Reinhard Fehling,London, England, assigner to ,Compania Uruguaya `de yFomento Industrial S. A., yMontevideo, Uruguay, Southv America `This invention relates to-Ameans for arresting or preventing the liow of a liquid from an open ended tube or Y the like and has particular but not exclusive reference to ink reservoirs used for writing instruments of the ball tip type.

Instruments of this type arenow well known; there is, for example, the ball tip type of instrument sold under lthe trademark Biro, and covered by such inventions described in U. S. Patent 2,397,229, filed March 26, 1946, and U. S. Patent 2,416,896, led March 4, 1947, and the specication of copending patent application Serial Number 657,597,1iled March 27, 1946, `now abandoned, which describe instruments of thesaid type.

Several diiferent constructions oit ink reservoir are satisfactory for use with writing instruments of this type amongst which the following may be mentioned by `way of example.

,consumed is described in copending application Serial -Number 104,242, filed July 12, 1949, now'Patent Number 2,672,127.

Yet a further modilication of ink reservoir has been 'described in which the ink reservoir is constituted by a tube which at one end communicates with the bail but which at the other end has ,a layer of a liquid more viscous than the ink. It will be appreciated that with all open ended-tubes containing liquids there is a slight tendency for the liquid to run out, by what is usually known as creep If the inner surface of the tube has any imperfections such as an axial scratch, the liquid tends to creep along such scratch; a small scratch is, in eiiect a tine bore duct and the ink is drawn therealong bycapillary action. Other causes of liquid creep are small errors in manufacture of the tube or faulty handling while in use.

It is an object of the present invention to prevent or arrest the ow of a liquid from an open ended tube.

if the internal diameter of the ink reservoir is not more than 2.5 mm. the meniscus formed in the ink column at the end remote from the ball is so strong that under normal conditions of use intemperate latitudes, it will not break and the ink will not creep out of the open end. The volume of ink in a reservoir of "2.5 mm. internal diameter is however, necessarily limited having regard lf the internal diameter of the reservoir is increased beyond 2.5 mm. internal diameter to atord a larger volume of inlcth'e risk of breakage of said meniscus or ink creepage is increased. The present invention resides, ltherefore, -in

`the provision of means for "arresting for preventing the *llow of a liquid-from aveuted-tubef-or thef-like, Vwhich 2,732,829 Patented Jan. 31, 1956 2 consists in the provision of at least one peripheral and continuous or substantially continuous step or groove formed on or in the inner surface of said tube and located at any convenient position between the said vent and that end of the column of liquid adjacent thereto in the `said tube when the tube is charged with said liquid, the

said step or groovebeing so arranged as to ai'ord a sharp change in direction of movement to uid tending to llow axially relatively thereto. In carrying the invention into effect it is preferred toprovide more than one of the said steps or grooves, all of which are separated from each other; they may be separated by a ridge or the like.

It will be readily appreciated that the prevention of ink creep in writing instruments ofthe type specified is one of considerable importance. -If a user of such an instrument touches the end of an ink reservoir in which creep has occurred, he will get ink on his hands; a state of affairs to be avoided. It is, therefore, a specific object of the present invention to prevent or arrest the flow of ink from ink reservoirs of writing instruments of the type speciiied by utilising a vented tube having the characteristics set out in the last preceding paragraph.

Any suitable ink may be employed in writing instruments of the type specied; examples of suitable inks are disclosed in co-pending patent applications Seiial Number 657,598, liled March 27, 1946, and Serial Number 659,149, led April 2, 1946, both -now abandoned.

In order that the invention may be more readily Vunderstood reference will now be made to the accompanying drawings in which:

Figure 1 shows (mainly in cross section and by way of example) a reservoir writing instrument of the type specified according to the invention.

`Figure 2 is a diagrammatic View of an ink reservoir according to this invention.

Figure is an alternative construction to Figure 2.

Figure 4 Vis another alternative construction of Figure 2.

Figure 5 is a detailed View of a split ring.

Figs. 6 and 7 show partly sectional, fragmental Views of embodiments of this invention.

The instrument shown in Figure'l comprises a writing extremity 1 which houses a ball 2 and is connected to a tubular reservoir 3. This reservoir communicates with the gap between the ball and its housing by means of a'srnall-diameter feed duct. The said gap and feed duct are not illustrated since they are well understood by these familiar with the construction of writing instruments of the type specified. It may be mentioned, however, that the ball is desirably in the order of 1 mm. in diameter, the diameter of the feed duct at that end thereof which communicates with the ball housing is less than that of the ball, and the width of the gap is preferably between 1 104 and l l03 cms.

The unit consisting of the Writing extremity ll and the reservoir 3, is housed in a casing consisting of a barrel 4 provided with an air hole 5 and an adaptor 6. Conveniently, but not necessarily, the writing extremity is screwed into the adaptor 6 at 7 and said adaptor and barrel are screwed together at 8. A cap, not shown, may be provided which when the instrument is not in use, ts over a ring in the casing at 13 to protect the Writing extremity and which, when the instrument is in use, is fitted over the other end of said instrument.

It will be observed that the rear end 9 (i. e. that end which is remote from the ball 2) of the tubular reservoir 3 is open so that the contents of the reservoir are exposed to atmospheric pressure at this end.

The ink constituting the writing fluid is shown at 10. The ink column forms a continuous vein of liquidexball and -its housing.

A recess groove or channel, located inside the reservoir 3, is illustrated at 12. This groove or channel is formed as a ring inside the reservoir so that it is between the meniscus 11 and the open end of the reservoir 9. The ring provides a step over which the lm of ink must ow.

In Figure 2 the ink column 10 is shown surmounted by a layer of another liquid 14 more viscous than the ink. In this specific example two

grooves

15 and 16 of square cross section are shown situated between the viscous liquid 14 and the open end of the tube 9.

In Figure 3 a piston or float 17 is shown resting on the top of the ink column l0. In this example the

grooves

18 and 19 are shown separated from each other by a sharp ridge 20. These grooves may be adjacent to each other as shown, or they may be of a certain distance from one another. The end of the reservoir is closed but the contents of the reservoir are maintained at atmospheric pressure by means of the small air vent 21.

An alternative constructional method of carrying the invention into effect is shown in Figure 4 which shows the rear end of an ink reservoir similar to that shown in Figure 2.

The grooves formed in the inside of the reservoir of Figure 2 are replaced by removable rings 23. A more detailed view of one of these rings is shown in Figure from which it will be seen that the ring 23 is a noncontinuous ring having a gap 26; formed in the inside of the ring is a V-shaped groove 22 having comparatively sharp edges 27 and 28. The ring is preferably of resilient material of such a size that when the ring is compressed so that the gap Z6 is closed (i. e. the two faces 24 and 25 separated by the gap 26 are in contact) the maximum diameter of the ring is the same as the internal diameter of the ink reservoir. The rings are pushed into the reservoir from the open end 9.and in Figure 4 it will be seen that two rings are provided with a short space 29 between them; preferably the gaps 26 are not in line with one another. Not only will the groove 22 in the rings act as a reservoir for any ink which may creep but also the gap 2g formed between the walls of the two rings 23 will also function as an ink reservoir. in these specic examples the cross sectional shape of the grooves or channels is square or V-shaped. It will be appreciated that any suitable cross sectional shape may be used but it is preferable to use a shape which will leave a comparatively sharp edge both for entering and leaving the groove when approached in a direction along the axis of the reservoir. The reason for the sharp edge is simply explained. When a liquid lm is creeping its surface tension will resist any tendency to a sudden change of direction, because in order to move over an edge the iilm surface has to be strongly curved. Such a curvature can only be produced if the liquid at this point is at a pressure higher than atmospheric. Such a high pressure can only be produced by force of gravity (in which case the liquid must first accumulate) or by shocks or the like. It is therefore, apparent that it is more important that the edge is sharp in the sense that the radius of curvature at this point is as small as possible.

The groove also acts as a reservoir for any creeping liquid. As the liquid creeps into the grooves the groove itself acts as a capillary reservoir thus causing the liquid to fill up the groove before trying to escape therefrom; by providing a plurality of grooves the total capacity is of course increased.

lt may be said that usually the total volume of ink which creeps during the life of one of these ink reservoirs (that is before all the ink in the reservoir is consumed by usage), is comparatively small. The ink capacity of one of the grooves according to this invention is very small compared with that of the ink reservoir, but is in general sufficient to accommodate the volume of ink which creeps.

Referring now to the constructions illustrated in Figures 6 and 7 it will be seen that in the construction shown in Figure 6 there are formed on the interior surface of the reservoir 3 a series of steps 30 each of which is normal to the longitudinal axis of the reservoir. In the construction shown in Figure 7 each step 30 has an obtuse angle to said axis. The ink column is represented at 3.9. the open mouth of the reservoir its flow is arrested by each step in turn for the reason that the ink, due to surface tension, exhibits a reluctance to eiect a violent change of direction in the ow. The number of steps may be varied as desired but in practice it is found that two or three are adequate to prevent ink owing out of the open mouth of the reservoir. A groove may of course be provided at the base of each step but the essential inhibition to ink creepage is the step itself and the advantage of the constructions illustrated in the embodiments shown in Figures 6 and 7 is that they can readily be produced by a moulding process and do not necessitate a separate operation such as is entailed in the formation of grooves after the tube has been produced.

It will be appreciated that in all the constructions illustrated herein the steps and grooves are so arranged that if a film of liquid attempts to ilow axially relatively thereto such lm will of necessity assume a marked degree of convexity over the sharp edge of the step or groove and it is this phenomenon which functions to arrest the ow.

While preferred embodiments of the invention have been disclosed to advantage, it is understood that modifications as to the Aarrangement and use of parts may be made without departing from the spirit and scope of the invention as claimed.

I claim:

l. A vented tube intended for the reception of a viscous liquid and suitable for use as an ink reservoir in writing instruments of the type having at least one peripheral and continuous step between the vent and the adjacent end of the liquid column, when the tube is charged with such liquid, said step providing a sharp angle on the inner surface of said tube and located intermediate said vent and that end of the column of liquid adjacent thereto in said tube when said tube is charged with said liquid, said step providing a passage of substantially similar diametric dimension as the inside diameter of said tube and in direct coaxial communication with the inner surface of said tube thereby aifording a sharp angular change in direction of movement to fluid tending to iiow axially relative thereto, the bore of the reservoir on either side of said step for preventing the flow of ink being substantially the same.

2. A vented tube intended for the reception of a viscous liquid and suitable for use as an ink reservoir in writing instruments of the type having between the vent and the adjacent end of the liquid column when the tube is charged with such liquid, a plurality of spaced peripheral and continuous steps formed in the inner surface of said tube, said steps being of successively wider area and located away from the longitudinal axis of said tube and disposed intermediate said vent and that end of the column of liquid adjacent thereto in said tube when said tube is charged with said liquid, thereby affording a sharp angular change in direction of movement to fluid tending to flow axially relative thereto.

3. A vented ink reservoir tube for a writing instrument having means for arresting or preventing the ow of ink from said vented tube, said means comprising a portion provided with a peripheral and substantially continuous recess formed along the inner surface of said tube, said recess being sharp-edged on the side of the column of ink to prevent the ow of ink into said recess, said recess being disposed intermediate said vent and the end of the column of liquid adjacent thereto in said tube when said tube is charged with said liquid, said recess being substantially coaxial with said tube and providing a passage of substantially similar diametric` dimension as the lf for any reason said ink tends to creep towardsinside diameter of said tube and in direct coaxial communication with the unrecessed inner surfaces of said tube thereby providing a sharp change in the direction of movement of lluid tending to flow axially relative thereto.

4. The combination according to claim 3, wherein said means is provided with a plurality of peripheral continuous recesses.

5. An ink reservoir tube for accommodating a column of ink therein for use in a ball point writing instrument having a vent for the admission of air and means for preventing creep of a film of ink along the interior surface of the tube towards said vent, said means comprising at least one peripherally continuous sharp-edged portion along the interior surface of said tube providing a passage in direct coaxial communication with the inside of said tube and of substantially similar diametric dimension as the inside diameter of said tube, the sharp edge being located on the side of the column of ink to prevent the ow of ink into said passage.

i 6. A tube according to claim in which said means is constituted by a ring inserted into the body of the tube.

7. A tube according to claim 6 in which the ring or each thereof is a split ring so arranged and designed that when inserted into the tube the ring is substantially closed and forms a sharp recessed edge to abruptly change the creepage of the ink in said tube toward the open end thereof.

8. An ink reservoir tube for accommodating a column of ink therein for use in a ball point writing instrument, said tube being provided with a vent for the admission of air as the ink is used up in writing, and means for hindering creep of a film of ink along the surface of said tube towards said vent, said means consisting of at least one abrupt sharp-edged peripheral steplike portion of substantially uniform width in the interior of said tube at a location inwardly of said vent, said step-like portion providing a passage of a diametric dimension at least as large as the inside diameter of said tube in direct substantial coaxial communication with the inside of said tube and presenting a sharp edge on the side of said steplike portion adjacent the column of ink to prevent the How of ink into said passage, the sharp edge extending completely around the interior of said tube and with at least a part thereof away from the longitudinal axis of said tube.

References Cited in the tile of this patent UNITED STATES PATENTS 682,574 Skilton Sept. 10, 1901 2,087,139 Cameron July 13, 1937 2,435,123 Biro Ian. 27, 1948 2,452,504 Teift Oct. 26, 1948 2,500,998 Morris Mar. 21, 1950 2,504,649 Chesler Apr. 18, 1950 2,519,635 Claret Aug. 22, 1950 FOREIGN PATENTS 571,698 Great Britain Sept. 5, 1945 582,186 Great Britain Nov. 7, 1946 254,826 Switzerland Jan. 3, 1949