Sample Injection Device Plunger Reference Position Adjustment

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Solution Overview

Problem

Conventional sample injection devices with pulse motor-driven plungers require manual adjustment of the reference position, leading to synchronization loss and inaccurate sample suction and discharge volumes, necessitating frequent recalibration when syringes are replaced.

Innovation Solution

A sample injection device equipped with a pulse motor, encoder, and control unit that automatically adjusts the plunger's reference position by detecting the operating position using an encoder and adjusting based on count values to maintain synchronization and precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the plunger is manually adjusted to bring the reference position as close as possible to the needle side end portion in the syringe, then the suction and discharge volume precision is improved, but the operation complexity increases and time is lost

Engineering Contradiction:

Improvesuction and discharge volume precisionVSAvoidmanual adjustment operation

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The system performs self-adjustment of the plunger reference position automatically. The control unit drives the plunger via the pulse motor to contact the needle side end portion, detects the operating position through the encoder, and automatically sets the reference position without requiring manual intervention, thus resolving the contradiction between precision and ease of operation

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The manual mechanical adjustment process is replaced by an automated control system comprising a pulse motor, encoder, and control unit. The control unit automatically controls the plunger position based on encoder feedback, substituting the manual mechanical adjustment with an automated electromechanical system that achieves both precision and ease of operation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If the plunger is brought into contact with the needle side end portion to adjust the reference position, then the volume precision is improved, but the pulse motor loses synchronization and reverses direction causing separation

Engineering Contradiction:

Improvereference position precisionVSAvoidpulse motor synchronization

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The encoder provides real-time feedback on the plunger's operating position to the control unit. When the plunger contacts the needle side end portion, the encoder detects this position and feeds it back to the control unit, which then sets the reference position accordingly. This feedback mechanism allows the system to achieve precise reference position setting without causing the pulse motor to lose synchronization permanently

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system intentionally allows the plunger to slightly exceed the normal operating range by contacting the needle side end portion during the adjustment process. This partial excessive action is controlled and monitored by the encoder feedback, enabling the system to establish an accurate reference position while the control unit prevents sustained synchronization loss by detecting the contact position and adjusting accordingly

Inventive Principle:

Principle #16Partial or excessive action

3Manufacturing precision

If manual adjustment is performed each time the syringe is replaced, then the reference position accuracy is maintained, but the productivity decreases due to repeated adjustments

Engineering Contradiction:

Improvereference position accuracyVSAvoidsyringe replacement efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The system automatically performs reference position adjustment whenever a syringe is replaced. The control unit detects the new syringe installation, automatically drives the plunger to contact the needle side end portion using the pulse motor, detects the position via the encoder, and sets the reference position without requiring manual intervention. This self-service capability maintains reference position accuracy while eliminating the time-consuming manual adjustment process, thereby resolving the contradiction between precision and productivity

Inventive Principle:

Principle #25Self-service

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

Enables automatic and precise adjustment of the plunger's reference position, reducing mechanical load and errors, and ensuring consistent sample injection and discharge volumes without manual intervention, even when syringes are replaced.

Implementation Method 1

an encoder configured to detect an operating position of the pulse motor

Methodology Applied

Scientific EffectEncoder detection:

Implementation Method 2

a plunger drive unit configured to drive the plunger by a pulse motor that operates in synchronization with pulse power

Methodology Applied

Scientific EffectPulse motor conversion:

Data Source

PatentUS11460479B2Sample injection device and method of adjusting sample injection device

Publication Date: 2022.10.04 SHIMADZU CORP

AI summary

This sample injection device is provided with a plunger drive unit for driving a plunger by a pulse motor, an encoder for detecting an operating position of the pulse motor, and a control unit for adjusting a reference position of the tip end of the plunger with respect to the syringe based on the operating position detected by the encoder when the tip end of the plunger is brought into contact with the end portion in the syringe on the tip end side.