Sample Injection Device Needle Penetration Speed Control
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Solution Overview
Problem
Conventional sample injection devices for gas chromatographs experience a decrease in airtightness and generate ghost peaks due to needle penetration variability, leading to damage of the rubber lid member and contamination of the analysis sample.
Innovation Solution
A sample injection device with a syringe drive mechanism controlled by a controller to adjust the needle's penetration speed, using a high speed until a predetermined depth and then a low speed to reduce displacement and friction, ensuring precise penetration and minimizing airtightness loss and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the syringe moving speed is increased to improve penetrating force of the needle, then the needle penetration capability is improved, but the syringe vibration increases causing position variation and airtightness deterioration
Solution Approach 1:
The syringe drive mechanism dynamically adjusts the moving speed of the syringe during the penetration process. The controller varies the speed according to the penetration stage: higher speed during initial penetration to overcome resistance, then reduced speed near the target position to minimize vibration and improve positioning accuracy. This dynamic speed adjustment resolves the contradiction between needing high penetrating force and maintaining position precision.
2Productivity
If the syringe moving speed is increased to reduce penetration time, then the analysis efficiency is improved, but the airtightness of the lid member deteriorates due to position variation
Solution Approach 1:
The syringe drive mechanism employs periodic acceleration and deceleration cycles during the penetration process. The controller implements a multi-stage speed profile with acceleration phases followed by deceleration phases, creating periodic motion patterns that reduce vibration and improve positioning accuracy while maintaining overall fast penetration time. This periodic action allows both high productivity and maintained airtightness.
3Speed
If the needle penetration speed is increased to improve analysis throughput, then the processing speed is improved, but thermal damage to the lid member increases causing ghost peak generation
Solution Approach 1:
The system dynamically controls the penetration speed to minimize thermal damage. The controller reduces the speed during the critical phase when the needle is in contact with the lid member, thereby reducing frictional heat generation. After successful penetration, the speed can be increased again. This dynamic speed modulation maintains high overall throughput while preventing thermal damage and ghost peak generation during the sensitive penetration phase.
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
Significantly reduces airtightness loss and ghost peak generation by maintaining precise needle placement and reducing thermal damage to the lid member, thereby improving analysis accuracy and efficiency.
Implementation Method 1
a lid member (911) configured to maintain airtightness of a sample introduction portion (910), and elastically deformable so as to allow the needle (11) to penetrate therethrough
Implementation Method 2
at least a moving speed at a time when the tip of the needle (11) contacts the lid member (911) is a second moving speed that is low
Data Source
AI summary
In a sample injection device (100), a controller (23) is configured or programmed to control a syringe drive (21) such that in a penetration operation in which a syringe (10) is moved to a side of a sample introduction portion (910) and a needle (11) penetrates a lid member (911), a moving speed at a time when a tip (11b) of the needle contacts the lid member is a second moving speed that is low.