Pipette Volume Screw Locking Mechanism
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Solution Overview
Problem
Conventional pipettes face difficulties in accurately adjusting liquid volumes due to the rapid rotation of the counter's drum relative to the operator-controlled screw, leading to challenges in reaching precise volume values, especially with large volume ranges and mechanical strength issues.
Innovation Solution
A locking device for the volume adjustment screw, comprising a ring dogging system with toothed wheels and a control system that allows for free adjustment, fine adjustment, and locking positions, enabling precise volume control without mechanical resistance during large volume scans and preventing accidental changes during pipetting operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a holding system is implemented to hold the volume adjustment screw in different positions, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The holding system transitions from a static locked state to a dynamic controllable state. The selector switch enables the system to dynamically change between locked and unlocked states, allowing the adjustment screw to be held in position when needed while permitting free adjustment when required. This dynamic control resolves the contradiction by making the holding function conditional rather than permanent.
Solution Approach 2:
The system changes the mechanical parameter of the holding force by using the selector switch to engage or disengage the holding mechanism. When the selector is in the locked position, the holding force is applied to maintain precise positioning; when unlocked, the holding force is released to allow free adjustment. This parameter change enables the system to adapt between precision holding and flexible adjustment needs.
2Measurement precision
If the elastic return means forces the toothed wheels to cooperate, then measurement precision is improved, but ease of operation deteriorates when scanning large volume ranges
Solution Approach 1:
The selector switch creates a dynamic system where the mechanical engagement between toothed wheels can be switched on or off. During large volume range scanning, the selector is positioned to disengage the holding mechanism, eliminating resistance and allowing easy rotation. When precise volume adjustment is needed, the selector engages the holding mechanism to provide precise positioning. This dynamic switching resolves the contradiction between ease of operation and measurement precision.
Solution Approach 2:
The adjustment process is segmented into two distinct modes: coarse adjustment mode for scanning large volume ranges and fine adjustment mode for precise volume setting. The selector switch enables transition between these segments. In coarse adjustment mode, the holding mechanism is disengaged for easy rotation; in fine adjustment mode, it is engaged for precision. This segmentation allows each mode to optimize for its specific function without compromising the other.
3Reliability
If the control member locks the lock wheel axially, then reliability is improved, but ease of operation worsens due to restricted adjustment
Solution Approach 1:
The locking mechanism is made dynamic through the selector switch, which can engage or disengage the axial locking of the lock wheel. When reliability is needed (during pipetting operations), the selector engages the lock to prevent accidental volume changes. When adjustment flexibility is needed, the selector disengages the lock to allow free adjustment. This dynamic control resolves the contradiction by making the locking function conditional rather than permanent.
Solution Approach 2:
The locking function is extracted as a separate controllable feature rather than being permanently integrated into the adjustment mechanism. The selector switch independently controls the locking state, allowing the user to separate the adjustment function from the locking function. This extraction enables the system to provide locking reliability only when needed, without permanently restricting adjustment flexibility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances ergonomic volume adjustment by allowing easy access to precise volume values while maintaining mechanical stability, facilitating accurate and efficient pipetting operations across various volume ranges without excessive operator effort.
Implementation Method 1
elastic return means capable of returning the first and second wheels against each other in order to make the first teeth cooperate with the second teeth
Data Source
AI summary
A device for locking a volume adjustment screw for a pipetting system, comprising a control member which rotates as one with a position selector, the member cooperating with a locking wheel such that: when the selector is in the free adjustment position, the member ensures that the wheel is axially spaced from another wheel, such that the teeth of the wheels do not cooperate with each other; when the selector is in the fine adjustment position, the member allows the wheel to move away from and then to move axially towards the other wheel while transitioning from one tooth to another; when the selector is in the locking position, the member axially locks the wheel to prevent the teeth from being disengaged.