Trocar Shaft Step Guide for Seal Extraction
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Solution Overview
Problem
The existing trocar apparatuses face difficulties in smoothly extracting the trocar shaft due to the formation of a step on the outer periphery of the trocar shaft, which can get caught by the seal unit, especially when a step is formed on the proximal side of the puncture member, hindering the axial movement and causing radial instability.
Innovation Solution
The trocar apparatus incorporates a design where the length from the distal end of the puncture member to the small diameter member is greater than the interval between the pipe section and the head section, ensuring smooth extraction by maintaining a stable axial movement, and includes a dome-type seal that elastically deforms to fit the treatment tool, with a centering guide and a second mount to support the seal unit, ensuring proper alignment and extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a step is formed on the outer periphery of the trocar shaft (to house the camera), then the camera can be accommodated, but the step gets caught by the seal unit, hindering smooth extraction of the trocar shaft
Solution Approach 1:
A guide groove is introduced as an intermediary structure between the step and the seal unit. The guide groove receives and guides the seal unit during insertion, allowing the step to pass through the seal unit smoothly without causing radial instability or extraction hindrance, while still accommodating the camera housing space
Solution Approach 2:
The guide groove extends in the axial direction, transforming a potential radial interference problem into an axial guidance solution. By providing a dimensional path along the axial direction, the step can move through the seal unit without causing radial instability
2Reliability
If the seal unit is made highly flexible to fit the treatment tool, then sealing performance is improved, but the seal unit may be caught by the step, causing radial instability
Solution Approach 1:
The guide groove acts as an intermediary that guides the flexible seal unit during insertion. The groove's shape and positioning ensure that the seal unit follows a controlled path, preventing it from being caught by the step while maintaining its flexibility for effective sealing
Solution Approach 2:
The guide groove is designed in advance to anticipate and prevent the seal unit from being caught by the step. By providing a pre-formed guidance path, the potential harmful interaction between the flexible seal and the step is eliminated before it can occur
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
This design allows for the smooth withdrawal of the trocar shaft even with a step on the outer periphery, preventing radial instability and ensuring effective sealing and insertion of the treatment tool, enhancing the operational efficiency of the trocar apparatus.
Implementation Method 1
The seal is made of a highly flexible material, and when the treatment tool or the trocar shaft is inserted in the seal opening, the seal is fitted so that no gap is formed around the treatment tool or the trocar shaft
Data Source
AI summary
A trocar apparatus includes a trocar and a trocar shaft. The trocar has a retractable-type camera section and a seal unit. The seal unit has a dome type seal and a first mount. A step is formed on the proximal side of a puncture member at the distal end of the trocar shaft. A relationship between a puncture member length L1 of the puncture member and an interval L2 in the axial direction of the trocar from the boundary position between a pipe section and a head section to a first mount opening satisfies conditional formula (A) given below:L1>L2 (A).