Dispensing Instrument Piston Trigger Mechanism
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Solution Overview
Problem
Existing dispensing systems for semi-solid implantable materials face limitations due to low user-generated force, nozzle clogging, and awkward handling, particularly when dealing with semi-solid materials, as they generate hydraulic pressure and require complex manipulations during surgical procedures.
Innovation Solution
A dispensing device with a pivotally mounted trigger connected to a gear wheel, which advances a piston rod through a cylinder with a constant inner diameter, allowing for efficient dispensing without the need for a separate latch and minimizing hand strain, while being designed for easy operation and hygiene during surgeries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a nozzle is used for dispensing semi-solid materials, then dispensing precision is improved, but hydraulic pressure builds up causing material overrun and nozzle clogging
Solution Approach 1:
The patent removes the nozzle component entirely from the dispensing system. Instead of forcing material through a restricted opening that creates hydraulic pressure, the piston directly contacts and pushes material out through the open end of the barrel, eliminating the pressure buildup that causes overrun and clogging while maintaining dispensing precision through direct control.
Solution Approach 2:
Rather than using a nozzle to restrict and direct flow (conventional approach), the invention inverts the approach by having the piston directly push material out through the open barrel end. This reverses the traditional dispensing mechanism, eliminating the harmful hydraulic pressure while achieving precise control through direct mechanical contact.
2Force
If a trigger is pivoted about an axis adjacent to the cylinder (mastic gun design), then mechanical advantage is provided for greater force, but the user's hand must be at full stretch making operation awkward
Solution Approach 1:
The patent merges the trigger pivot axis with the main body of the handle, positioning it centrally rather than at the periphery. This integration allows the user's hand to rest naturally on the handle body while operating the trigger, eliminating the need for the hand to be at full stretch. The mechanical advantage is preserved through the lever action of the trigger while improving ergonomics by combining the pivot with the handle structure.
3Reliability
If a separate spring loaded latch is used to prevent piston rod retraction, then piston control is improved, but device complexity increases requiring additional manipulation
Solution Approach 1:
The patent combines the latch function with the trigger mechanism itself. The trigger, when depressed, directly controls both piston advancement and prevents retraction through its mechanical position. This integration eliminates the need for a separate spring-loaded latch mechanism, reducing device complexity while maintaining reliable piston control through the unified trigger operation.
Solution Approach 2:
The trigger is designed to perform multiple functions: it advances the piston when depressed and simultaneously prevents piston rod retraction through its mechanical engagement. This multi-functionality eliminates the need for separate components, simplifying the device while maintaining reliable control over the piston mechanism throughout the dispensing cycle.
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 device provides a simpler, more efficient, and stable dispensing mechanism that reduces hydraulic pressure issues and clogging, allowing for precise control and ease of use, even in surgical settings, accommodating various cylinder diameters and lengths.
Implementation Method 1
A spring biases the trigger so that, upon its release, it returns to its starting position allowing further movement of the trigger to selectively depress the piston and dispense more material.
Implementation Method 2
The trigger is coupled to a gear wheel which is arranged to advance the piston rod when the trigger is depressed.
Implementation Method 3
the trigger is coupled to a gear wheel which is arranged to advance the piston rod when the trigger is depressed
Data Source
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AI summary
A delivery device for semi-solid implantable material such as synthetic bone graft substitution. The device comprises a handle (1), a cylinder (2) extending from the handle and having an outlet at its distal end. A piston (23) is operated by a trigger (5) and is slidable within the cylinder to displace the material from the cylinder. The cylinder has a substantially constant inner diameter along its entire length such that the outlet has substantially the same inner diameter as the rest of the cylinder. When the trigger is fully depressed, a ratchet mechanism (14, 32) is disengaged allowing the piston to be pulled back to a starting position.