US 3521969 A
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July 28, 1970 o.-VMUTS :HLER
FRONT END ASSEMBLY FOR A FUNTAIN PEN 2 Sheets-Sheet l Filed Dec. 27, 1968 IIIIIII.
07?@ Mu fsa; ler- 4 A G-E /VTS July 28, 1970 o. MUTSCHLER FRONT END ASSEMBLY FOR A FOUNTAIN PEN 2 Sheets-Sheet 2 Filed Dec. 27, 1968 /n ven/or:
AGEA/7 United States Patent O 3,521,969 FRONT END ASSEMBLY FOR A FOUNTAIN PEN Otto Mutschler, Angelweg 29, Heidelberg, Germany Filed Dec. 27, 1968, Ser. No. 787,434 Claims priority, application Germany, Feb. 3, 1968, M 61,289 Int. Cl. B431( 5/18 U.S. Cl. 401-225 14 Claims ABSTRACT OF THE DISCLOSURE The front end assembly for a fountain pen normally supplied with ink in cartridges has a tubular point holder whose axial passage is divided into front and rear compartments by an apertured radial partition. A feed bar in the front compartment abuts agains the raised rim of the aperture orifice, and its rotation is prevented by a rib on the point holder projecting into a notch in the rear end of the feed bar. Ink from a cartridge is supplied from the aperture to a writing point at the front end of the point holder through a capillary slot whose radial depth increases from the point to the aperture orifice and which intersects annular grooves in an intermediate portion of the feed bar. Air is supplied to the grooves through an axial duct in the feed bar surface extending inward from the front end.
BACKGROUNDv OF THE INVENTION This invention relates to fountain pens, and particularly to a front end assembly of a fountain pen capable of accomodating ink cartridges.
It is common practice to provide fountain pens of the type referred to with front end assemblies which can be separated from the barrel of the pen and include a point holder bounding a receptacle for a writing point which partly projects from the point holder in an axially forword direction. Ink supply to the point and the admission of air to the ink reservoir of the pen are controlled by a feed bar received in the tubular point holder.
The object of the invention is the provision of a front end assembly for such a pen which consists of only a few unitary elements of sufficiently simple shape to permit these parts to be produced from plastics by injection molding with minimal mechanical finishing operations after molding, and which controls ink and air ow in a particularly reliable manner even under varying conditions of ambient pressure and temperature.
SUMMARY OF THE INVENTION In one of its aspects, the invention resides in a front end assembly in which an axial passage through the point holder is divided by a fixed, radial partition into a major front compartment and a minor rear compartment connected by an aperture in the partition. A raised rim projects from the partition about the orifice of the aperture in the front compartment.
A feed bar is secured in the front compartment by friction against axial movement in axially abutting engagement of its rear end with the raised rim on the partition. The feed bar and the point holder jointly define a conduit connecting the orifice on the partition with the receptacle for the writing point in the point holder. The feed bar also is formed with an axially elongated, radially open notch which extends forwardly from the rear end of the feed bar, and into which a rib on the point holder radially projects to prevent rotation of the feed bar. External threads are provided for fastening the point holder to a pen barrel.
Other feature, additional objects, and many of the attendant advantages of this invention will readily be ap preciated as the same becomes better understood by ref- 3,521,969 Patented July 28, 1970 erence to the following detailed description of a preferred embodiment when considered in connection with the attached drawing.
BRIEF DESCRIPTION OF THE DRAWING In the drawing:
FIG. 1 shows a front end assembly of the invention and a portion of a connected ink cartridge in axial section;
FIG. 2 shows the assembly of FIG. 1 and a portion of an alternate ink supply mechanism partly in axial section, internal elements of the front assembly being shown in elevation; and
FIGS. 3 to 8 show the front end assembly of FIGS. 1 or 2 in radial section on the lines III-III to VIII--VIII respectively.
DESCRIPTION OF THE PREFERRED EMBODIMENT The illustrated front end assembly consists of three unitary elements, a tubular, plastic point holder 30, a plastic feed bar 31, the rear portion of which is approximately coaxially received in the point holder, and a metallic writing point 32.
A recess 1 diametrically opposite the point 32 at the front end of the feed bar 31 permits the bar to be axially withdrawn from the axial passage of the point holder 30 in which it is normally secured by a friction fit. The front end 2 of an air duct which is open in a radially outward direction extends rearward from the recess 1. An axial throttling portion 3 of the duct which is axially coextensive with the rear end of the point 32 has a reduced cross section and leads rearwardly into another deep duct portion 4 whose bottom wall, that is, the wall nearest the axis of the assembly, is of arcuate cross section in the axially sectional view of FIG. 1, but also in radial section as viewed in FIG. 2. The duct portion 4 terminates near the rear end of the feed bar 31 where it communicates with an annular circumferential groove 5 in the bar.
The groove 5 is shallower than the duct portion 4, and it liares axially in a radially outward direction. The portion of the groove 5 diametrically opposite to the duct portion 4 communicates with a radially and rearwardly open notch 6 in the bar 31 which extends through the rear end of the bar.
A slot 7 extends inward of the bar 31 from the surface of the bar diametrically opposite the duct 2, 3, 4. Its circumferential width is minimal, as best seen in FIGS. 3 and 4, so that the slot acts as a capillary ink duct. It extends axially in the bar 31 from the front end of the point holder 30 through the rear end of the feed bar 31. The slot increases in radial depth in a rearward direction, being quite shallow where it is directly under the point 32, of intermediate depth where it is axially coextensive with the duct portion 4, and thereafter deepening steeply so that its depth is greater than the radius of the feed bar in the rear face of the latter.
As is best seen from FIG. 6i, when jointly considered with FIG. 2, the front end of the feed bar 31 under the Writing point 32 is formed With two groups of lateral notches 8 extending circumferentially away from each side of the writing point 32 in axially offset relationship'. The notches 8 of each group are axially connected by a recess 9 in the bar, but are separated from the duct 2 by wall portions 10 of the bar which sealingly engage the inner wall of the point holder 30.
The aforementioned groove 5 is the rearmost member of a group of substantially identical grooves 11 in the intermediate axial portion of the feed bar 31 in which the slot 7, which intersects the grooves 5, 11, is of uniform intermediate depth greater than the depth of the grooves, which are also connected by the rear portion 4 of the air duct.
A rib 12 on the inner surface of the point holder 30 engages the notch 6 of the feed bar 31, and thereby secures the bar against rotation in the point holder. In its illustrated operative position, the feed bar 31 axially abuts against an integral radial partition 13 of the point holder which divides the passage of the latter into a front compartment and a rear compartment radially bounded by the externally threaded, terminal rear portion 21 of the point holder 30.
The partition 13 has a recess 14 adjacent the rib 12 and thus' axially aligned with the notch 6 which is only partly obstructed by the rib, as is best seen in FIGS. 3 and 4. The recess 14 also communicates with a shallower annular channel defined between a radial end wall of the feed bar 31 and an annular front face of the partition 13 between the inner face of the point holder 30 and an axially projecting annular rim 15. A depression 16 in the rim 15, shallower than the recess 14 and radially aligned with the same, connects the recess to the orifice of a relatively wide aperture 18 in the partition 13. The aperture extends rearwardly through a hollow cylindrical pin 17 coaxial and integral with the partition 13. Three capillarly slots 19 extend from the aperture 18 into the pin 17 and the partition and are axially coextensive with the same.
A shallow depression 22 in the inner wall of the point holder 30 adjacent the front end of the latter provides a receptacle for the point 32 in the usual manner. The pin 17 is dimensioned for insertion into the front end of an ink cartridge 25, and displaces a ball valve 24 normally closing the cartridge end when inserted, as is conventional (FIG. 1).
Internal threads 23 in the Tear portion 21 of the point holder 30 alternatively permit the front assembly to be connected with the mouth piece 26 of a conventional collapsible ink chamber, not itself shown (FIG. 2).
The afore-described front assembly operates as follows.
The ink cartridge normally used with the front-end assembly of the invention is entirely filled with ink until the cartridge is opened by engagement of the ball valve 24 with the pin 17. Ink is displaced by entry of the pin into the cartridge and is driven into the three capillary slots 19 and the aperture 18. It further enters the slot 7. Ink thereafter is drawn toward the receptacle 22 and the point 32 by capillary attraction in the communicating slots 19 and 7.
The ink discharged from the cartridge 25 is replaced by air which enters the cartridge through the ducts 2, 3, 4, the groove 5, the notch 6, the recess 14, the depression 16, and the aperture 18.
If the air in the cartridge 25 expands because of a sudden temperature increase, or because of a sudden drop in ambient air pressure, the shallow depression 16 is quickly flooded with ink, and additional air is thereby prevented from entering the cartridge. Further expansion of the air in the cartridge causes ink to fill the recess 14, the annular space about the raised rim 15, the notch 6, the annular groove 5, and ink may ultimately enter the rear portion 4 of the air duct in the surface of the feed bar 31 diametrically opposite the slot 7, and the point 32. Axial flow of the ink through the air duct portion 4 is retarded or prevented by the relatively great radial depth and by the rounded configuration of the duct portion 4 so that excess ink is retained by the grooves 11. Ink does not readily flow forward under the point 32 at a rate higher than its normal discharge by writing because of the shallowness of the slot 7 adjacent the point 32.
If ink should flow forward beyond the grooves 11, it cannot readily enter the front portion 2 of the air duct. The throttling portion 3 of the duct is normally effective in preventing axially forward ink flow from the duct portion 4, and the front portion 2 is laterally closed by the wall portions 10 of the feed bar 31. Any excess ink penetrating forward from the grooves 11 is trapped in the notches 8 which communicate through the axially elongated recesses 9. As soon as the flooding condition subsides, air can therefore again enter the duct portion 2 and be drawn backward into the grooves 11 as the ink therein is depleted by writing or by contraction of the air in the cartridge 25.
The front en-d assembly of the invention operates in substantially the same manner when supplied with ink from a collapsible rubber chamber in a conventional manner, as partly illustrated in FIG. 2.
What is claimed is:
1. A front-end assembly for a fountain pen comprising, in combination:
(a) an elongated point holder member (30) having a longitudinal axis, being formed with an axial passage therethrough, and bounding a receptacle (22) for a portion of a writing point (32);
('b) radial partition (13) fixed in said passage and dividing the same into a major front compartment (20) and a minor rear compartment, said partition being formed with an aperture (18) connecting said compartments, and having a raised rim (15) in said front compartment extending about the orifice of said aperture;
(c) a feed bar (31) secured in said front compartment against axial movement in axially abutting engagement of the rear end portion of said feed bar with said raised rim,
(l) said feed bar and said point holder member jointly defining an air conduit (2, 3, 4, 5, 6, 14, 16) an-d an ink conduit (7) connecting said orifice with the ambient air at the front end of said passage and with said receptacle respectively,
(2) said feed bar being formed with an axially and radially open notch (6) in said rear end portion thereof;
(d) a rib (12) on said point holder member radially projecting into said notch for preventing rotation of said feed bar about said axis; and
(e) fastening means for fastening said point holder member to a pen barrel.
2. An assembly as set forth in claim 1, wherein said ink conduit includes a slot (7 of capillary circumferential width, said slot extending axially in an outer face of said feed bar from said receptacle to said rear end, and radially inward from said outer surface, the radial depth of said slot increasing from said receptacle toward said rear end, a portion of said feed bar axially intermediate said receptacle and said rear end portion being formed with a plurality of axially offset circumferential grooves (11, 5), said slot intersecting said grooves and communicating with said orifice.
3. An assembly as set forth in claim 2 said slot intersecting said notch (6), and said notch axially extending into the circumferential groove (5) nearest said partition and communicating with said aperture (18) through a recess (14, 16) in said partition open toward said front compartment, said notch and said nearest groove constituting portions of said air conduit.
4. An assembly as set forth in claim 3, wherein said recess (14, 16) extends radially from said notch (6) through said rim (15) to said orifice and is bounded axially by said rear end portion, a portion (16) of said recess spaced from said notch being of reduced cross section.
5. An assembly as set forth in claim 2, said partition being formed with a plurality of capillary slots (19) axially substantially coextensive with said aperture and communicating with said aperture.
6. An assembly as set forth in claim 2, said air conduit being constituted in part by an axially elongated air duct (2, 3, 4) formed in said feed bar and circumferentially spaced from said receptacle (22), said air duct being Open in an axially forward direction and a radially outward direction, and being bounded in said radially outward direction by said point holder, said air duct having a rear portion (4) intersecting said circumferential grooves (11, 5) and a throttling portion (3) forwardly offset from said rear portion and having a smaller cross section than said rear portion.
7. An assembly as set forth in claim 6, the radial depth of said rear portion of the air duct being greater than the radial depth of said circumferential grooves, and the bottom wall of said rear portion radially inwardly olfset from said grooves being of arcuate section in a radial plane and in an axial plane.
8. An assembly as set forth in claim 6, two wall portions of said feed bar circumferentially bounding a front portion (2) of said air duct axially substantially coextensive with said receptacle, said wall portions sealingly engaging said point holder member in said front compartment.
9. An assembly as set forth in claim 8, said Wall portions being each formed with a plurality of notches (8) extending from said receptacle (22) circumferentially toward said front portion of the air duct in axially spaced relationship, but being sealed from said duct by said wall portions.
10. An assembly as set forth in claim 9, each wall portion being formed with an axially elongated recess (9) connecting said notches (8) in the wall portion.
11. An assembly as set forth in claim 1, wherein said rear compartement is open in an axially rearward direction, and said point holder member is formed with an internal thread (23) about axis in said rear compartment.
12. An assembly as set forth in claim 1, said point holder member, said partition, and said rib jointly consituting a unitary body of plastic.
13. An assembly as set forth in claim 1, wherein a portion of said ink conduit is constituted by a slot (7) in said feed bar, said slot having a front portion axially coextensive with said receptacle, a rear portion axially extending through said rear end portion of the feed bar, and an intermediate portion connecting said front and rear portions, the radial depth of said front portion being smaller than the radial depth of said intermediate and rear portions, and the depth of said rear portion of the slot increasing continuously from the depth of said intermediate portion to a depth greater than one half the radial thickness of said feed bar, the radial depth of said intermediate portion being uniform, the circumferential width of said slot being smaller than the radial depth of said front portion thereof.
14. An assembly as set forth in claim 1, wherein a portion of said air conduit is constituted by an axially elongated air duct in said feed bar, said air duct having a forwardly open front Iporton (2), a rear portion (4), and a throttling portion (3) intermediate said front and rear portions and having a smaller cross section than said front and rear portions of said air duct.
References Cited UNITED STATES PATENTS 2,417,861 3/1947 Dahlberg 401-226 2,581,739 l/1952 Wing 401-225 2,881,737 4/1959 Young 401-227 X 3,289,640 l2/1966 Rosler et al. 401-227 LAWRENCE CHARLES, Primary Examiner