Pipette with adjustable volume of aspirated liquid
Pipette with adjustable volume of aspirated liquid built of a handle ( 1 ) and of a nozzle ( 3 ) and of coupled with them: an exchangeable pipette tip ejection mechanism, a drawing up and discharging mechanism with a plunger ( 12 ) arranged in said pipette nozzle ( 3 ), a plunger working stroke adjustment mechanism with at least one driving member ( 16 ), a manually actuated lock mechanism locking a drive assembly of an adjustment screw of a plunger working stroke, an engaging mechanism which engages said plunger working stroke adjustment mechanism with a counter ( 14 ) of an aspirated liquid volume by said pipette, a calibration mechanism for a change of a pipette calibration coefficient, whereas said driving member ( 16 ) of said drive assembly of said adjustment screw of the plunger working stroke is accessible from outside through at least one window ( 38 ) in a wall of said handle ( 1 ), said pipette is characterized in that said lock mechanism of said drive assembly of said adjustment screw of the plunger working stroke comprises a lock member which is non-rotatably mounted relative to said pipette handle ( 1 ) and is axially slidable between LOCKED POSITION and UNLOCKED POSITION of said plunger working stroke adjustment mechanism, whereas said driving member ( 16 ) of said drive assembly of said adjustment screw of the plunger working stroke is axially fixedly and rotatably mounted relative to said pipette handle ( 1 ).
1. A pipette with an adjustable volume of an aspirated liquid built of a handle ( 1 ) and of a nozzle ( 3 ) and of coupled with them
an exchangeable pipette tip ejection mechanism comprising an ejector push button ( 7 ) seated in the upper part of said handle ( 1 ) and an ejector ( 9 ) seated with its lower end onto said nozzle ( 3 ),
a drawing up and discharging mechanism comprising a pipetting push button ( 5 ) connected via a pipetting rod ( 6 ) with a piston assembly ( 11 ) of which a plunger ( 12 ) is placed in said nozzle ( 3 ),
a plunger working stroke adjustment mechanism provided with a drive assembly of an adjustment screw of a plunger working stroke with at least one driving member ( 16 ), a manually actuated lock mechanism locking said plunger working stroke adjustment mechanism,
an engaging mechanism engaging said plunger working stroke adjustment mechanism with a counter ( 14 ) for indicating a volume of a liquid aspirated by said pipette depending on the set plunger working stroke,
a calibration mechanism for a change of a pipette calibration coefficient determining a relationship between a plunger movement length which is set by said plunger working stroke adjustment mechanism and the liquid volume indicated in said counter, whereas
said driving member ( 16 ) of said drive assembly of said adjustment screw of the plunger working stroke is accessible from outside through at least one window ( 38 ) in a wall of said handle ( 1 ),
characterised in that
said lock mechanism locking said plunger working stroke adjustment mechanism comprises a lock member which is non-rotatably mounted relative to said pipette handle ( 1 ) and is axially slidable along an axis defined by the pipetting rod ( 6 ) between LOCKED POSITION and UNLOCKED POSITION of said plunger working stroke adjustment mechanism, whereas
said driving member ( 16 ) of said drive assembly of said adjustment screw of the plunger working stroke is axially fixedly and rotatably mounted relative to said pipette handle ( 1 ), and
said lock mechanism locking said plunger working stroke adjustment mechanism constitutes a friction brake between said lock member and said driving member ( 16 ), whereas said lock member has a frictional surface ( 31 ) on an inner cone and said driving member ( 16 ) has a frictional surface ( 32 ) on an outer cone.
2. The pipette according to claim 1 , characterised in that said driving member ( 16 ) of said drive assembly of said adjustment screw of the plunger working stroke is via said pipetting rod ( 6 ) rotatably fixedly coupled with said pipetting push button ( 5 ) of said drawing up and discharging mechanism.
3. The pipette according to claim 1 , characterised in that said lock member is axially slidably mounted onto said driving member ( 16 ) of said drive assembly of said adjustment screw of the plunger working stroke and non-rotatably mounted in said pipette handle ( 1 ).
4. The pipette according to claim 1 , characterised in that angles of said inner and outer cones of said frictional surfaces ( 31 , 32 ) are equal.
5. The pipette according to claim 1 , characterised in that said lock member is a braking sleeve ( 15 ).
6. The pipette according to claim 1 , characterised in that said lock member is provided with an elastic braking element ( 39 ) braking an axial movement of said lock member in said pipette handle ( 1 ) in UNLOCKED POSITION of said plunger working stroke adjustment mechanism.
7. The pipette according to claim 1 , characterised in that said driving member ( 16 ) of said drive assembly of said adjustment screw of the plunger working stroke is axially fixedly mounted relative to said pipette handle ( 1 ) by an interlock ( 18 ) which is releasable from said driving member ( 16 ) for axial displacing said driving member ( 16 ) during the pipette disassembly.
8. The pipette according to claim 1 , characterised in that said lock member has an outer surface which facilitates a grip.
9. The pipette according to claim 2 , characterised in that said lock member is axially slidably mounted onto said driving member ( 16 ) of said drive assembly of said adjustment screw of the plunger working stroke and non-rotatably mounted in said pipette handle 1 ).
10. The pipette according to claim 9 , characterised in that angles of said inner and outer cones of said frictional surfaces ( 31 , 32 ) are equal.
11. The pipette according to claim 10 , characterised in that said lock member is a braking sleeve ( 15 ).
12. The pipette according to claim 3 , characterised in that angles of said inner and outer cones of said frictional surfaces ( 31 , 32 ) are equal.
13. The pipette according to claim 12 , characterised in that said lock member is a braking sleeve ( 15 ).
14. The pipette according to claim 4 , characterised in that said lock member is a braking sleeve ( 15 ).
15. The pipette according to claim 14 , characterised in that said lock member is provided with an elastic braking element ( 39 ) braking an axial movement of said lock member in said pipette handle ( 1 ) in UNLOCKED POSITION of said plunger working stroke adjustment mechanism.
16. The pipette according to claim 5 , characterised in that said lock member is provided with an elastic braking element ( 39 ) braking an axial movement of said lock member in said pipette handle ( 1 ) in UNLOCKED POSITION of said plunger working stroke adjustment mechanism.
17. The pipette according to claim 16 , characterised in that said driving member ( 16 ) of said drive assembly of said adjustment screw of the plunger working stroke is axially fixedly mounted relative to said pipette handle ( 1 ) by an interlock ( 18 ) which is releasable from said driving member ( 16 ) for axial displacing said driving member ( 16 ) during the pipette disassembly.
18. The pipette according to claim 6 , characterised in that said driving member ( 16 ) of said drive assembly of said adjustment screw of the plunger working stroke is axially fixedly mounted relative to said pipette handle ( 1 ) by an interlock ( 18 ) which is releasable from said driving member ( 16 ) for axial displacing said driving member ( 16 ) during the pipette disassembly.
19. The pipette according to claim 18 , characterised in that said lock member has an outer surface which facilitates a grip.
20. The pipette according to claim 7 , characterised in that said lock member has an outer surface which facilitates a grip.