Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3175734 A
Publication typeGrant
Publication dateMar 30, 1965
Filing dateDec 3, 1962
Priority dateDec 3, 1962
Publication numberUS 3175734 A, US 3175734A, US-A-3175734, US3175734 A, US3175734A
InventorsLouis R Heiss
Original AssigneeAmerican Instr Company Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Titration apparatus
US 3175734 A
Abstract  available in
Images(1)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

March 30, 1965 R. HEISS 3,175,734

TITRATION APPARATUS Filed Dec. 3, 1962 INVENTOR.

EM A 00/5 /8 H E 155 ATTORNEY United States Patent 3,175,734 'liTRATION APPARATUS Louis R. Heiss, Silver Spring, Md assignor to American instrument Company, Inc, Silver Spring, Md. Filed Dec. 3, 1962, Ser. No. 241,575 8 Claims. (ill. 222-481) This invention relates to titration apparatus, and more particularly to a burette or titration device having readily interchangeable pipette elements.

A main object of the invention is to provide an improved titration apparatus arranged for easy and rapid changing of its pipette and plunger elements, whereby the same main titration apparatus may be used for accurately dispensing different reagents, as required, by merely changing its pipette and plunger subassembly, and whereby there is no risk of contaminating 'the reagent with which the device is employed by the presence of material employed in a previous use of the apparatus.

A further object of the invention is to provide an improved automatic titration apparatus provided with means for easily and quickly changing its plunger and pipette elements, the apparatus being simple in construction, being compact in size, and being easy to manipulate.

A still further object of the invention is to provide an improved burette or titration device having readily interchangeable pipette and plunger elements, the device being durable in construction, being relatively inexpensive to manufacture, and permitting different titrations or liquid dispensing operations to be performed in rapid sequence and with high accuracy.

A still further object of the invention is to provide an improved changeable plunger and pipette subassembly for a burette or titration apparatus, said subassembly being easy to handle, being quickly and easily replaceable without requiring tools or complex manipulations, and involving only a few simple and easily manufacturable parts.

Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein:

FIGURE 1 is a front elevational view of an improved automatic titration apparatus constructed in accordance with the present invention.

FIGURE 2 is a vertical cross-sectional view taken substantially on line 2-2 of FIGURE 1.

FIGURE 3 is an enlarged fragmentary elevational view of a removable pipette and plunger subassembly employed in the titration apparatus of FIGURES 1 and 2.

FIGURE 4 is a top plan view of the assembly shown in FIGURE 3.

Referring to the drawings, 11 generally designates an improved titration apparatus constructed in accordance with the present invention. The apparatus 11 is of the automatic type similar generally to the apparatus disclosed in US. Patent No. 2,925,198 to Sidney Healey. Said apparatus comprises a vertical generally L-shaped plate 15 having the depending arm 16 and the horizontally extending top arm 17. Secured to plate 15 is a housing 18 which includes a horizontally extending top portion 19 and an integral depending tubular vertical portion 21 A reversible electric motor 32 is mounted on plate portion 16 and is drivingly connected to a horizontal worm shaft 22 journalled in housing top portion 19, said worm shaft carrying the worm 23 which meshes with a worm wheel 24 journalled vertically in and rotatably supported in housing portion 19, said worm wheel having an internally threaded hub which is threadedly engaged with the externally threaded shank 26 of a vertical driving plunger member 25. Said plunger member is axially positioned in the vertical tubular housing portion 20, and the enlarged lower portion of the plunger memher is formed with a frusto-conical bore or recess portion 27.

A radially extending horizontal guide pin 28 is secured to the enlarged lower portion of plunger member 25 and extends slidably through a vertical guide slot 29 formed in the depending vertical tubular housing portion 20.

Designated at 30 is a generally L-shaped plate member which is vertically secured to housing portion 19 at its top end and which is secured to the lower margin of plate portion 16 at its bottom end, as by transverse bolts 31 provided with spacer sleeves 21 between plate member 3%) and plate portion 16 so that plate member 30 is secured in parallel reationship to plate portion 16. Mounted on plate member 30 are the respective upper and lower mircoswitches 76 and 77 connected to control the energization of the motor 32 in the manner described in the above-mentioned prior Patent No. 2,925,198. A two-pole three-position switch 86 is mounted on plate portion 16 and a speed-control potentiometer 84 is mounted on the lower portion of plate member 30, the switch 86 and potentiometer 84 being connected in circuit with the microswitches 76, 77 and the reversible motor 32 in the manner described in the aforesaid prior patent to control the vertical movements of plunger member 25. Plate member 30 is formed with a vertical slot 73 through which pin 28 projects so that it is engageable with the operating arms of the microswitches 76 and 77 at the upper and lower limiting positions of plunger member 25. With switch 86 operated in one direction, the motor 32 will be energized in a direction to move plunger member 25 downwardly, and the downward movement of said plunger member will continue until pin 28 engages the operating arm of lower microswitch '77, thereby opening the motor circuit. Conversely, the switch 86 may be operated in the opposite direction causing the motor to be energized in the reverse direction and to move plunger member 25 upwardly until pin 28 engages the operating arm of the upper microswitch 76, which again breaks the motor circuit. Switch 86 is normally in an open-circuit position, as described in the afore-mentioned prior Patent No. 2,925,198.

A counter 40, provided with a resetting knob 41, is mounted on plate portion 17 and is connected to worm shaft 22 through a coupling 42.

Designated generally at 43 is a replaceable titrant reservoir assembly of the displacement type comprising a plunger element 44 which extends into and is moveable axially in the bore portion of a dispensing pipette 45. The plunger element 44 is sealingly slid-able through an annular Teflon sealin ring 86 which is clamped between a rigid washer 81 and the flanged top rim 46 of the pipette. A resilient O-ring 82 is provided beneath top rim 46 and another resilient O-ring 83 is provided in an annular groove formed in the underside of the yieldable Teflon sealing ring 89, said Owing 83 engaging the rigid top rim 46. The sealing assembly comprising the members 81, 86,63, 46 and 82 is sealingly clamped in the externally threaded enlarged lower portion of a bushing member 47, by means of an externally knurled annular cup-shaped clamping ring 68 threadedly engaged on the enlarged lower portion of bushing member 47, as shown in FIGURE 2.

The upper portion of bushing member 47 is formed with a generally L-shaped slot 48 open at its top end. Secured in the lower end portion of tubular housing member 20 is an inwardly projecting locking pin 49 which is engageable in slot 43 and which cooperates with the horizontal lower portion thereof to releasably retain the assembly 43 in the bottom end of housing member 20.

Rigidly secured in the bushing member 47 is an up wardly extending cylindrical thin metal sleeve 50 which slidably receives the enlarged lower portion of driving plunger 25, said sleeve being formed with a vertical slot 51 to provide clearance for pin 28. As shown in FIGURE 2, sleeve 50 terminates below the top end of slot 29 to allow pin 28 to be elevated above said sleeve, whereby to permit rotation of the assembly 43 when it is being removed from or inserted in the apparatus.

Secured on the top end of plunger element 44 is a head member 52 having a frusto-conical top portion 53 snugly receivable in the tapered bore portion 27 of member 25. A locking bolt 54 extends through the bore of member 25 and is threadedly engageable in the top end of head member 52, said bolt being provided with the knurled head 55 which bears against the top rim of shank portion 26 to allow head member 52 to be drawn tightly into the tapered bore portion 27, whereby to lock plunger element 44 to the driving plunger 25.

A vertical cover cap 56 is threadedly engaged in an upstanding collar 57 integrally formed on a bracket plate 58 secured on the top wall of housing portion 19, the collar 57 being coaxial with the driving plunger 25 and the cap 56 being of sufficient height to allow vertical movement of the driving plunger through its full upward stroke. The cap 56 is readily removable to provide access to the knurled head 55.

When the subassembly 43 is to be removed, the plunger 25 is first elevated so that pin 28 is in an elevated position clear of sleeve 50, as shown in dotted view in FIGURE 2. Cap 56 is then removed and bolt 54. is unscrewed, untastening head 52. The subassernbly 43 is then rotated by means of knurled member 68 through a sufficient angle to bring the vertical portion of slot 48 into alignment with pin 49. The subassembly can then be moved downwardly and withdrawn from the housing portion 20. A replacement subassembly 43 may be attached to the titration apparatus by following a reverse procedure.

In inserting a replacement subassembly 43, rotation thereof to bring the pin 49 substantially into contact with the closed end of the horizontal portion of slot 48 automatically vertically aligns slot 51 with pin 28. In this position, the frusto-conical portion 53 of head member 52 will be closely received in the tapered bore portion 2'] so that it can be subsequently locked tightly thereagainst by means of the locking bolt 54.

The cylindrical lower portion of head member 52 has secured thereon a collar member 70 of resilient deformable material which slidably engages the inside surface of sleeve member '3 and acts to maintain the head member 52 in a centered position therein.

The plunger element 44 is of constant-cross-sectional area cylindrical shape and may be made of suitable stable plastic material, such as Vycor, or the like. The plunger element is advanced into the reservoir 45 by means of the precision screw member 26, displacing a volume of titrant linearly related to the screw advance. The digital counter 40 provides digital read-out in volumetric units of titrant dispensed.

While a specific embodiment of an improved titration apparatus has been disclosed in the foregoing description, it will be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore it is intended that no limitations be placed on the invention except as defined by the scope of the appended claims.

What is claimed is:

1. In a titration apparatus of the character described, a support, a vertical tubular housing secured to said support, a hollow driving plunger slidably mounted in said tubular housing, a dispensing pipette, cooperating pin and bayonet slot means detachably connecting said pipette to the bottomend of said housing, said driving plunger having a bottom recess, a plunger element sealingly and slidably received-in said pipette, a head member on said plungerelement closely fitting and received in said recess, and removable bolt means extending from the top of the housing substantially through the entire length of said hollow driving plunger and secured to said head memher, said bolt means causing the head member to be drawn tightly into said recess and to rigidly lock the plunger element to the driving plunger.

2. In a titration apparatus of the character described, a support, a vertical tubular housing secured to said support, a hollow driving plunger slidably mounted in said tubular housing, a dispensing pipette, a supporting bushing, means sealingly securing said pipette to said supporting bushing, said bushing being formed at its top end with a generally L-shaped slot, an inwardly projecting locking pin in the lower portion of said housing, said bushing being engageable in said lower housing portion with the pin lockingly engaged with said L-shaped slot, whereby to detachably connect said pipette to the bottom end of said housing, said driving plunger having a bottom recess, a plunger element sealingly and slidably received in said pipette, a head member on said plunger element closely fitting and received in said recess, and removable bolt means extending from the top of the housing substantially through the entire length of said hollow driving plunger and secured to said head member, said bolt means causing the head member to be drawn tightly into said recess and to rigidly lock the plunger element to the driving plunger.

3. In a titration apparatus of the character described, a support, a vertical tubular housing secured to said support, a hollow driving plunger slidably mounted in said tubular housing, a dispensing pipette, a supporting bushing, means sealingly securing said pipette to said supporting bushing, said bushing being formed at its top end with a generally Lshaped slot, an inwardly projecting locking pin in the lower portion of said housing, said bushing being engageable in said lower housing portion with the pin lockingly engaged with said L-shaped slot, whereby to detachably connect said pipette to the bottom end of said housing, said driving plunger having a bottom recess, a plunger element sealingly and slidably disposed in said pipette, a head member on said plunger element closely fitting and received in said recess, and a headed bolt having its shank portion extending from the top of the housing substantially through the entire length of said hollow driving plunger and being threadedly engaged with said head member, said bolt causing the head member to be drawn tightly into said recess and to rigidly lock the plunger element to said driving plunger.

4. In a titration apparatus of the character described, a support, a vertical tubular housing secured to said support, a hollow driving plunger slidably mounted in said tubular housing, a dispensing pipette, a supporting bushing, means sealingly securing said pipette to said supporting bushing, said bushing being formed at its top end with a generally L-shaped slot, an inwardly projecting locking pin in the lower portion of said housing, said bushing being engageable in said lower housing portion with the pin lockingly engaged with said L-shaped slot, whereby to detachably connect said pipette to the bottom end of said housing, said driving plunger having a downwardly flaring substantially frusto-conical bottom recess, a plunger element sealingly and slidably disposed in said pipette, a head member on said plunger element having a frusto-conical top portion closely fitting and received in said recess, and a headed bolt having its shank portion extending through said hollow driving plunger and being threadedly engaged with said head member.

5. In a titration apparatus of the character described, a support, a vertical tubular housing secured to said support, a hollow driving plunger slidably mounted in said tubular housing, a dispensing pipette, a supporting bushing, means sealingly securing said pipette to said supporting bushing, said bushing being formed at its top end with a generally L-shaped slot, an inwardly projecting looking pin in the lower portion of said housing, said bushing being engageable in said lower housing portion with the pin lockingly engaged with said L-shaped slot, whereby to detachably connect said pipette to the bottom end of said housing, an upstanding sleeve element secured in said bushing and being received in said housing around said driving plunger, outwardly projecting guide pin means on said plunger, said sleeve element and said housing being formed with registrable vertical slots through which said guide pin means extends, to limit relative rotation of said driving plunger with respect to said sleeve element, the vertical slot in said sleeve element being open at its top end, said driving plunger being movable at times to a position wherein said guide pin means is located above said sleeve element, whereby to allow such relative rotation at said times, said driving plunger having a bottom recess, a plunger element sealingly and slidably disposed in said pipette, a head member on said plunger element closely fitting and received in said recess, and removable bolt means extending through said hollow driving plunger and detachably secured to said head member.

6. The structure of claim 5, and wherein said bolt means comprises a headed bolt having its shank portion extending through said hollow driving plunger and being threadedly engaged with said head member.

7. The structure of claim 6, and wherein the means sealingly securing said pipette to said supporting bushing includes an externally knurled clamping ring threadedly engaged on the lower portion of the bushing.

8. A pipette and dispensing plunger attachment for a titration apparatus comprising an annular supporting bushing having an enlarged externally threaded lower portion,

a pipette having an annular top sealing flange disposed in said enlarged lower portion, an externally knurled clamping ring threadedly engaged on said enlarged lower portion, sealing means between said clamping ring and said sealing flange and between said sealing flange and said enlarged lower portion cooperating with said clamping ring to sealingly secure said flange in said enlarged lower portion, the upper portion of said bushing being formed with a generally L-shaped slot open at its top end, a plunger element sealingly and slidably extending through said sealing means between the sealing flange and the enlarged lower portion, said plunger element extending into said pipette, said plunger element having an upwardly tapering frusto-conical top end and being internally threaded at said last-named top end, an upstanding sleeve element secured in said bushing, said sleeve element being formed with a vertical slot open at its top end, and a headed anchoring bolt threadedly engaged in said last-named top end.

References Cited by the Examiner UNITED STATES PATENTS 325,642 9/85 VJorthen 222-567 X 2,765,955 10/56 Natelson 22232 2,925,198 2/60 Healey 22232 2,946,486 7/60 Gilmont 222-38 LOUIS J. DEMBO, Primary Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US325642 *Sep 1, 1885 Oil-can
US2765955 *Oct 19, 1953Oct 9, 1956Samuel NatelsonUniversal automatic titrator
US2925198 *Sep 4, 1956Feb 16, 1960American Instr Company IncTitration apparatus
US2946486 *May 29, 1957Jul 26, 1960Manostat CorpAnalytical device
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3915651 *Sep 22, 1972Oct 28, 1975Us GovernmentDirect digital control pipette
US4086062 *Feb 23, 1977Apr 25, 1978Hach Chemical CompanyDigital titration device
US4198483 *Mar 15, 1978Apr 15, 1980Olympus Optical Company, LimitedPipette exchange apparatus
US4215092 *Jul 11, 1978Jul 29, 1980Osmo A. SuovaniemiApparatus for liquid portioning and liquid transferring
US4241018 *May 10, 1979Dec 23, 1980Mettler Instrumente AgApparatus with exchangeable burettes
US4369665 *Apr 25, 1979Jan 25, 1983Indicon Inc.Manually holdable automatic pipette
US5002737 *Nov 15, 1988Mar 26, 1991Labsystems OyElectrically operated pipette
US5133218 *Apr 15, 1991Jul 28, 1992Tritech PartnersSample liquid aspirating and dispensing probe
US5159842 *Jun 19, 1991Nov 3, 1992Eastman Kodak CompanySelf-cleaning pipette tips
DE2929307A1 *Jul 19, 1979Apr 3, 1980Mettler Instrumente AgWechselbuerette
WO1991001486A1 *Nov 17, 1989Feb 7, 1991Tritech PartnersNew and improved sample liquid aspirating and dispensing probe
Classifications
U.S. Classification73/864.14, 222/333, 222/32, 422/925, 422/75, 222/390, 422/509
International ClassificationB01L3/02
Cooperative ClassificationB01L3/0224
European ClassificationB01L3/02C3D
Legal Events
DateCodeEventDescription
Apr 5, 1982ASAssignment
Owner name: SLM INSTRUMENTS, INC., 810 ANTHONY DR., URBANA, I
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:BAXTER TRAVENOL LABORATORIES, INC.;REEL/FRAME:003967/0196
Effective date: 19820331