Home position locating mechanism for manual pipette and manual pipette equipped with same
AssigneeMettler-Toledo Rainin, LLC
InventorsJames S. Petrek, William D. Homberg
Life of this patent
Estimating the term…
Abstract
A pipette home position locating mechanism and a manual pipette equipped with such a home position locating mechanism. The home position locating mechanism is spring-biased but compressible in a proximal-to-distal direction. The spring preload force of the home position locating mechanism is selected to be greater than force of exerted by a stroke spring of the pipette to which the home position locating mechanism is attached while the stroke spring is at its blowout position, but less than the combined force exerted by the stroke spring at its blowout position and a blowout spring of the pipette in its preload position.
Claims23
A pipette home position locating mechanism for installation to a pipette having a stroke spring and a soft stop home position indicated by a blowout spring, the mechanism comprising:
- a lower component having a distal end adapted for attachment to a plunger rod of the pipette;
- an upper component forming a user-engageable plunger button portion and coupled to the lower component in an axially displaceable manner;
- and
- a preloaded compliance spring located between the lower component and the upper component such that the upper component is normally biased away from the lower component with a gap between said components;
- wherein a preload force exerted by the compliance spring is selected to be greater than the force exerted by the stroke spring at its blowout position, but less than the combined force exerted by the stroke spring at its blowout position and the blowout spring in its preload position.
A pipette home position locating mechanism for installation in the body of a pipette having a stroke spring and a soft stop home position indicated by a blowout spring, the mechanism comprising:
- a lower component adapted for installation into a cavity in the body of the pipette, and having a distal end adapted for communication with a plunger rod of the pipette;
- an upper component retained in an axially displaceable arrangement within a counterbore in the proximal end of the lower component, the upper component having a proximal end adapted for connection to a plunger button of the pipette;
- and
- a preloaded compliance spring located between the lower component and the upper component such that the upper component is normally biased away from the lower component with a gap between said components;
- wherein a preload force exerted by the compliance spring is selected to be greater than the force exerted by the stroke spring at its blowout position, but less than the combined force exerted by the stroke spring at its blowout position and the blowout spring in its preload position.
A manually-operated pipette, comprising:
- a pipette body having a proximal end and a distal end;
- a plunger assembly, the plunger assembly including a piston located for reciprocating movement within the pipette body and a plunger rod that extends proximally upward from the piston;
- a preloaded stroke spring that resides within the pipette body;
- a preloaded blowout spring that resides within the pipette body, the blowout spring acting as a soft stop indicator of pipette home position;
- and
- a home position locating mechanism, the home position locating mechanism comprising:
- a lower component,
- an upper component coupled to the lower component in an axially displaceable manner;
- and
- a preloaded compliance spring located between the lower component and the upper component such that the upper component is normally biased away from the lower component with a gap between said components;
- wherein, a preload force exerted by the compliance spring of the home position locating mechanism is greater than the force exerted by the stroke spring of the pipette at its blowout position, but less than the combined force exerted by the stroke spring at its blowout position and the blowout spring in its preload position.
Dependencies are inferred from the claim text.