US2756597A

US2756597A - Pipette

Info

Publication number: US2756597A
Application number: US396545A
Authority: US
Inventors: Koblanski John
Original assignee: Individual
Current assignee: Individual
Priority date: 1953-12-07
Filing date: 1953-12-07
Publication date: 1956-07-31
Anticipated expiration: 1973-07-31

Description

J. KOBLANSKI PIPETTE Filed Deo. 7, 1953 /NVENTOR Jfl ,MMNLL M W/ f nali/ ggf,

`Iuly 3l, 1956 ATTORNEY United States Patent() y PIPETTE John Koblanski, Edmonton, Alberta, Canada Application December 7., 19.53; Serial .-N o. 396,545

4 Claims. (Cl. 73-425.6)

This device relates generally to pipettes and more particularly to a pipette that may be used in a wide variety of liquids with equal efficiency.

Present day pipettes generally fall into either the vacuum or suction types or into types using a piston. The majority of these are found to be unsatisfactory owing to their tendency toward sudden surges and consequent unevenness in their action.

It is therefore an object of my device to provide a pipette that has a very stable, constant action when in use.

An additional disadvantage of present day pipettes is their intricate construction and assembly which makes it extremely dificult to disassemble the pipette for cleaning or to interchange portions of the pipette when required.

It is therefore an additional object of my device to pro vide a pipette having a convenient readily dismantled assembly which permits a rapid change of pipette ends and bores when requires.

A further object of my device is to provide a pipette incorporating a freely floating valve whose use greatly reduces the strain on the delicate parts of the pipette assembly.

Various other objects and advantages of my device will become apparent to those skilled in the art on reading the following specification in the light of the attached drawings.

In the attached drawings there is illustrated only one practical embodiment of the inventive idea and it must be understood that the embodiment illustrated and described is by way of example only and is not to be construed as a limitation. The invention herein is to be limited only by the terms of the appended claims and by the prior art.

In the drawings Figure l is an elevation mostly in section, of the upper portion of my pipette assembly.

Figure 2 is a top view taken along the line A-A in Figure l.

Figure 3 is an elevation again partly in section, of the lower end of my pipette assembly.

The device comprises the upper master cylinder 3 adapted to contain the inner head 6 which has the body 7 connected threadably thereto by the threads 20. The inner head 6 is prevented from turning within the master cylinder 3 by means of the lateral pin 4 engaged threadably in the wall of the master cylinder 3 and projecting thereinto, into the slotted portion 18 of the inner head 6. The master cylinder 3 is associated further with the inner head 6 by the internal guide posts 10--10 which are adapted to fit slidably in the inner head 6 against the action of the compression spring 13.

The body 7 is provided with the central channel 9 which contains the ball 8, adapted to seal off the duct 21 at the intake of the body 7. At the upper end of the body 7 there is provided the channel 19 for the passage of air into the master cylinder 3.

In the head 6 there is provided the central channel 22 2,756,597 Ratented July 31, 1956 ice whichfis threaded at 20 to receive the threaded rod 2. llfhe rod 2 extends through the head 6 down into the channell 9 in the body '7. 'As' will be seen from Figure 3 in the drawings the end of the rod 2 -terminates in the channel 9 and it will be obvious immediately that the adjustment ofthe end ofthe rod will determine the maximum upward travel o f vlthe ball valve 8K.

Vertical adjustment of the yrod 2 in the channel 19 is accomplished by the gears 14 and15 at the top of the master cylindery 3. As will be seen Abest from Figure l in the drawings, the rod 2 is provided with a longitudinally extending slot 17 which fits a mating guide in the gear wheel 15. Rotation of the large wheel 14 will result in the simultaneous opposite rotation of the small gear 15 which through the slot 17 in the rod, will cause rotation of the rod. Rotation of the rod 2 will cause it to rise upwardly or travel downwardly throughout its threaded portion 20 and in accordance with the direction of rotation of the small gear 15.

In operation the pipette would be held preferably between the thumb and third fingers of the users hand with the index finger placed upon the grip 5 on the master cylinder 3. Pressure on the grip 5 will lower the master cylinder 3 down over the body 7 and compress the air within the master cylinder 3 and in the channel 9. The compression of the air will force the ball 8 downwardly to expel any liquid in the pipette and will eventually force the ball 8 to the end of the pipette as seen in Figure 3 in the drawings.

Immediately prior to the master cylinder 3 reaching its lowest limit with respect to the body 7, the projection 11 on the valve 1 will come into contact with the protuberance 12 in the head 6 and will force the valve 1 upwardly against the compression spring 16 and allow the exhaustion of air from within the master cylinder 3.

When the pressure on the grip 5 is released, the compression spring 13 will force the master cylinder 3 upwardly and the valve 1 will be acted upon by the compression spring 16 and closed. As the cylinder 3 travels upwardly with respect to the body 7, the ball 8 will also move upwardly and if the body 7 is immersed in a liquid, such liquid will be drawn into the pipette end by way of the duct 21. The intake of liquid behind the floating ball 8 will continue until the ball 8 comes into contact with the lower end of the rod 2. The position of the lower end of the rod 2 will have been adjusted prior to the insertion of the pipette end in the liquid. The positioning of the end of the rod 2 within the body 7 is accomplished by rotating the large wheel 14 to move the rod 2 upwardly or downwardly to its correct position with respect to the external zero indicator 23 seen at the top of the master cylinder 3 in Figure l in the drawings.

It will be understood that the form of the invention described and illustrated is but by way of example, and such modifications may be resorted to as fall within the scope of the claims.

What I claim as my invention is:

l. In a pipette, a master cylinder having one closed end; a body inserted in the other end thereof in airtight longitudinal sliding engagement therewith to define an airtight chamber within the master cylinder; a head fixed to the body in the master cylinder, there being a longitudinal bore in the body and a channel in the head leading from the bore to the airtight chamber in the master cylinder; a ball adapted to operate slidably throughout the bore in the body; a valve in the master cylinder adapted to remain normally in the closed position and to be opened to allow exhaustion of air from the master cylinder; a rod in sliding engagement with the master cylinder, extending longitudinally therethrough and through the head into the body and means mounted on the said master cylinder for adjusting the rod longitudinally throughout the bore of the body.

2. A pipette as claimed in claim 1 wherein there is provided spring means in the master cylinder operable between the master cylinder andthe head.

3. A pipette as claimed inclaim 1 wherein the rod is in threaded engagement with the head and the rod adjusting means comprises a plurality of externally manipulatable gears operatively connected to the rod and adapted to rotate the rod. v

4. A pipette as claimed in claim 2 wherein the rod is in threaded engagement `with the head and the rod adjusting means -comprises a plurality of externally 4 manipulatable gears operatively connected to the rod and adapted to rotate the rod.

References Cited in the file of this patent UNITED STATES PATENTS 993,269 Mowers May 23, 1911 2,530,909 Riggs Nov. 21, 1950 2,660,342 Ruf NOV. 24, 1953 FOREIGN PATENTS 239,388 Great Britain Sept. l0, 1925 149,461 SwitzerlandV Nov. 16, 1931