US3424536A - Plunger assembly and writing instrument - Google Patents

Plunger assembly and writing instrument Download PDF

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Publication number
US3424536A
US3424536A US602906A US3424536DA US3424536A US 3424536 A US3424536 A US 3424536A US 602906 A US602906 A US 602906A US 3424536D A US3424536D A US 3424536DA US 3424536 A US3424536 A US 3424536A
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US
United States
Prior art keywords
plunger
guide sleeve
thread
buttress
threads
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US602906A
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English (en)
Inventor
Alfred Dottlinger
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Individual
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Individual
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Publication date
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Publication of US3424536A publication Critical patent/US3424536A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B43—WRITING OR DRAWING IMPLEMENTS; BUREAU ACCESSORIES
    • B43K—IMPLEMENTS FOR WRITING OR DRAWING
    • B43K24/00—Mechanisms for selecting, projecting, retracting or locking writing units
    • B43K24/02—Mechanisms for selecting, projecting, retracting or locking writing units for locking a single writing unit in only fully projected or retracted positions
    • B43K24/08—Mechanisms for selecting, projecting, retracting or locking writing units for locking a single writing unit in only fully projected or retracted positions operated by push-buttons

Definitions

  • a plunger assembly which has special utility in writing instruments, such as ball-point pens, having an extensible and retractible writing tip carrier consists of a plunger and a guide sleeve At least one of the parts is made of elastic material to permit radial movement between the parts.
  • At least one of said parts has a buttress thread, which cooperates with the other of said parts.
  • Said buttress thread has a trailing flank which has an angle of lead which is so small that said trailing flank is self-locking when it engages said other part.
  • the buttress thread has also a pressure face, which has an angle of lead which is larger than any angle of lead that would render said pressure face self-locking when engaging said other part. The self locking action prevents rotation of the plunger in the sleeve during forward movement of the plunger. When the plunger is released, a retracting spring causes the plunger to rotate to a forward or rear locked position along the pressure flank of the buttress thread.
  • This invention relates to a writing instrument, particularly a ball-point pen, which comprises a plunger mechanism, which consists only of a guide sleeve and a springloaded plunger, which is mounted for rotational and guided longitudinal movement and by a mere pressure on its end face is caused to snap alternately into a forward notch and a rear one.
  • Writing instruments having such a mechanism which consists only of two parts have the advantage that the writing tip carrier can be pushed into and locked in its writing position and unlocked and retracted to itsinoperative position without complicated manipulations, and that only two parts must be manufactured for the plunger assembly.
  • the detent elements are integral with the plunger and the guide sleeve, respectively, the plunger being integral with a detent element and the guide sleeve being integral with another detent element.
  • the writing instrument according to the invention is mainly characterized in that the plunger and/ or the guide sleeve are radially resilient relative to each other and provided on their periphery or a portion of their periphery with buttress threads, which have such a lead that the trailing flanks of the threads have an inclination within the self-locking range and the pressure flanks of the threads have an inclination outside said range.
  • the self-locking action prevents a rotation of the plunger in the threads of the guide sleeve during the forward movement of the plunger.
  • the same wedge action resiliently forces the plunger and the guide sleeve apart in a radial direction until the pressure flank of the buttress thread of the plunger snaps over the pressure flank of the female screw thread of the guide sleeve.
  • the retracting spring causes the same to rotationally slide into the forward or rear locked position along the pressure flanks of the buttress threads, which pressure flanks have an inclination outside the self-locking range. This locked position is determined by the respective end of the screw threads, their lead, and their axial offset.
  • the guide sleeve and/or plunger is provided with an abutment rib for engagement with the top end of the screw thread of the plunger, and/or the plunger is provided with an abutment rib for engagement with the lower end of the female screw thread of the guide sleeve.
  • These abutment ribs serve also for guiding the respective screw threads during the forward movement of the plunger and positively prevent a disturbing rotation of the plunger toward this rib under the influence of an eccentric and inclined force.
  • the abutment and guide rib is inclined to the longitudinal axis of the writing instrument in the same direction as the screw thread. This design anticipates the disturbing rotation of the plunger from the abutment and guide rib and ensures a positive guidance of the plunger and an undisturbed function of the plunger assembly under the action of any eccentric or inclined force, whether this force acts on the plunger on the left or right of its center.
  • the plunger or the guide sleeve is provided on its periphery or a portion of its periphery with buttress threads, which are closely spaced in the longitudinal direction, the lead of the screw threads is a multiple of their pitch, and the ends of the two screw threads on the same part are approximately on the same radial plane.
  • This design facilitates the axial Sliding movement of the plunger, a sufficiently large projection of the writing tip carrier from the forward end of the body of the writing instrument, and a high strength of the plunger assembly under axial load, even Where plastics material is used, as the 'axial force is taken up mainly by the overlapping pressure flank portions of the buttress thread of the plunger and of the guide sleeve.
  • a sufliciently large radial clearance is required for the guide sleeve in the body of the writing instrument or for the plunger, more particularly its buttress threads, in the guide sleeve.
  • the cross-section of the latter should be weakened or shaped in such a manner that it can be gently deflected during its forward movement.
  • the plunger has suitably an enlarged portion near its lower end and this enlarged portion has a funnel shaped cavity for centrically receiving the upper end of the writing tip carrier.
  • the outside diameter of said enlarged portion corresponds approximately to the inside diameter of the adjacent portion of the body.
  • the funnel itself is suitably shaped in such a manner that it adds to the flexural compliance of the plunger.
  • FIG. 1 is an elevation showing a guide sleeve in the form of a clip-retaining screw
  • FIG. 2 is an elevation showing the associated plunger having two buttress threads, the upper ends of which are on the same radial plane,
  • FIG. 3 shows partly in section the plunger assembly consisting of a guide sleeve of FIG. 1 and a plunger of FIG. 2 in assembled condition and screw into the upper part of the body of the writing instrument with the writing tip carrier in retracted or inoperative position,
  • FIG. 4 is an elevation showing the same assembly with the plunger and writing tip carrier in writing position
  • FIG. 5 is an elevation showing the same assembly with a plunger which has been fully depressed beyond the writing position
  • FIG. 6 is an elevation, partly in section, showing a guide sleeve which has two female buttress threads and is screwed into the upper part of the instrument body, which is injection-molded with an integral clip, the ends of the butress threads of the guide sleeve being on the same radial plane, 1
  • FIG. 7 is an elevation showing a corresponding plunger having a single buttress thread
  • FIG. 8 is an elevation of a guide sleeve which is formed by the upper portion of an instrument body and intended to cooperate with a plunger having a single buttress thread,
  • FIG. 9 is an elevation showing the plunger for cooperation with this guide sleeve
  • FIG. 10 is an elevation showing a modification of the plunger guide of FIG. 8, and
  • FIG. 11 is an elevation showing the plunger for cooperation with the guide of FIG. 10.
  • a plunger 3 is slida'bly and rotationally guided in the upper end portion 1 of the body of the writing instrument or in a clip-retaining screw 2 or guide sleeve 4 (FIG. 6) screwed into such upper portion.
  • the plunger acts on the writing tip carrier 5, which is loaded by a retracting spring.
  • the detent means on the plunger comprise two buttress threads 6 and 7, which extend around a portion of the periphery of the plunger.
  • the pressure flank 23 of the buttress thread 6 can slide back along the pressure flank 9 of the guide sleeve or clip-retaining screw 2 until the triangular end face 10 of the second buttress thread 7 engages the abutment rib 11 of the guide sleeve, and/ or the abutment rib 12 of the plunger 3 engages the triangular end face 24 of the mating female buttress thread 22 of the guide sleeve or clip-retaining screw 2 when the rear or initial position of the plunger 3 and the inoperative position of the writing tip carrier, FIG. 3, has been reached.
  • the plunger 3 is being depressed toward the clip-retaining screw 2, as is shown in FIG.
  • the plunger will initially move freely in an axial direction in its guide along the abutment rib 11 until the wedge-shaped trailing flank 13 of the second buttress thread 7 engages the corresponding trailing flank 14 of the female buttress thread in the clip-retaining screw 2.
  • the trailing flanks 13 and 14 have preferably the same inclination.
  • the lower buttress thread 7 snaps over the pressure flank 9 of the female buttress thread 22 in the lower portion of said pressure flank 9 and the pressure flank 23 of the thread 7 then slides back along the pressure flank 9 until the triangular end face 15 of the upper buttress thread 6 of the plunger engages the lower end of the abutment rib 13 and/ or the triangular abutment face 25 of the plunger 3 engages the triangular end face 24 of the female buttress thread 22 of the clip-retaining screw 2 so that the writing tip carrier is locked in writing position, as shown in FIG.
  • FIGS. 15 two buttress threads 6, 7 on the plunger and a single female buttress thread 22 are used.
  • FIGS. 7-11 show plungers having only one buttress thread 16 and cooperating guide sleeves having two female buttress threads 26 and 27.
  • FIGS. 6, 8 and 10 show an abutment rib 19 which is inclined relative to the longitudinal direction of the writing instrument in the same direction as the respective thread 16 (FIGS. 7, 9, and 11), and serves also as a guiding rib during the forward movement of the plunger.
  • the plunger 3 has one buttress thread 16.
  • the writing tip carrier is now in writing position.
  • the same operation is repeated, with the difference that the pressure flank 23 of the buttress thread 16 of the plunger resiliently snaps over the lower portion of the pressure flank which is engageable with the pressure flank along this pressure flank to its initial position.
  • the guide sleeve 4 or the clip-retaining screw 2 is elastic in a radial direction.
  • the assemblies shown in FIGS. 8-11 operate with a flexural elastic deformation of the plunger.
  • the plunger may be so weakened or shaped in its cross-section that it can be gently deflected and easily actuated.
  • a plunger assembly consisting of two parts, namely, a guide sleeve and a plunger which is axially and rotationally movably mounted in said guide sleeve, at least one of said parts being elastically movable relative to the other in a radial direction, at least one of said parts having a buttress thread, which has a trailing flank engageable with the other of said parts and having an angle of lead which is sufliciently small to render said trailing flank self-locking relative to the other of said parts when in engagement therewith, and a pressure flank engageable with the other of said parts and having an angle of lead which is larger than any angle of lead which would render said pressure flank self-locking relative to the other of said parts when in engagement therewith.
  • each of said parts is provided with two of said buttress threads, which are spaced 180 apart, and said plunger is provided with a longitudinal slot between its two buttress threads so that the latter can yield radially inwardly and snap over said buttress threads of said sleeve.
  • a writing instrument which comprises a body, a writing tip carrier which is contained in and longitudinally movable relative to said body between an extended writing position and a retracted position, means urging said Writing tip carrier toward its retracted position, and a plunger assembly carried by said body and arranged to control the position of said writing tip carrier, said plunger assembly consisting of two parts, namely, a guide sleeve and a plunger which is axially and rotationally movably mounted in said guide sleeve, at least one of said parts being elastically movable relative to the other in a radial direction, at least one of said parts having a buttress thread, which has a trailing flank engageable with the other of said parts and having an angle of lead which is sufliciently small to render said trailing flank self-locking relative to the other of said parts when in engagement therewith, and a pressure flank engageable with the other of said parts and having an angle of lead which is larger than any angle of lead which would render said pressure flank self-locking relative to the

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  • Mechanical Pencils And Projecting And Retracting Systems Therefor, And Multi-System Writing Instruments (AREA)
US602906A 1965-12-21 1966-12-19 Plunger assembly and writing instrument Expired - Lifetime US3424536A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AT1147165A AT280848B (de) 1965-12-21 1965-12-21 Druckmechanik für Schreibstifte

Publications (1)

Publication Number Publication Date
US3424536A true US3424536A (en) 1969-01-28

Family

ID=3628914

Family Applications (1)

Application Number Title Priority Date Filing Date
US602906A Expired - Lifetime US3424536A (en) 1965-12-21 1966-12-19 Plunger assembly and writing instrument

Country Status (6)

Country Link
US (1) US3424536A (de)
AT (1) AT280848B (de)
DE (1) DE1297513B (de)
ES (1) ES334705A1 (de)
FR (1) FR1505207A (de)
NL (1) NL6617956A (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11794510B2 (en) 2021-10-27 2023-10-24 Nottingham Jr Lee Vig Double-locking clicker mechanism and uses thereof

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3179087A (en) * 1960-08-30 1965-04-20 Kahn David Inc Writing instrument

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2857882A (en) * 1956-12-27 1958-10-28 Ferber Corp Retractable ball point writing implement

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3179087A (en) * 1960-08-30 1965-04-20 Kahn David Inc Writing instrument

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11794510B2 (en) 2021-10-27 2023-10-24 Nottingham Jr Lee Vig Double-locking clicker mechanism and uses thereof

Also Published As

Publication number Publication date
FR1505207A (fr) 1967-12-08
NL6617956A (de) 1967-06-22
AT280848B (de) 1970-04-27
DE1297513B (de) 1969-06-12
ES334705A1 (es) 1967-11-01

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