Syringe Pump Plunger Tip Geometry for Seal Wear Reduction
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Solution Overview
Problem
The automatic analysis devices face frequent maintenance due to uneven wear of the seal components in syringe pumps, leading to liquid leakage and inaccurate analysis results, particularly because the seal components made of soft materials are prone to damage from uneven wear and pressure loss.
Innovation Solution
The syringe pump design incorporates a power transmission plate with an inclined tip and point contact with the plunger components, eliminating moments and reducing uneven loads on the seal piece, thereby delaying wear and extending the maintenance cycle by ensuring the seal piece operates without additional stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the seal component is made of soft material to seal the liquid, then sealing performance is improved, but uneven wear occurs due to sliding resistance and pressure loss
Solution Approach 1:
The patent changes the geometric parameters of the plunger, specifically making the tip surface asymmetric with different radii of curvature (R1 and R2) on opposite sides. This parameter modification allows the plunger to vary its contact point with the cam during rotation, distributing the load more evenly across the seal component and reducing uneven wear while maintaining effective sealing.
Solution Approach 2:
The patent introduces dynamic variation in the plunger-cam contact relationship. By designing the plunger tip with asymmetric curvature, the contact point dynamically shifts during cam rotation, preventing constant localized stress on the seal component. This dynamic load distribution extends the service life of the seal while maintaining sealing effectiveness.
2Ease of manufacture
If the plunger contact surface is fixed, then manufacturing is simplified, but the contact surface hits the cam edge causing early wear
Solution Approach 1:
The patent modifies the plunger tip geometry by creating an asymmetric surface with different radii of curvature (R1 and R2) on opposite sides. This parameter change enables the plunger to naturally vary its contact position with the cam during rotation, preventing the contact surface from hitting the cam edge while maintaining manufacturing feasibility through standard machining processes.
3Duration of action of moving object
If tolerances and backlashes of each part are reduced to prevent uneven wear, then seal component life is extended, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent changes the plunger tip geometry to an asymmetric design with different radii of curvature. This parameter modification compensates for tolerances and backlashes in the mechanism by creating a self-adjusting contact pattern, thereby extending seal component life without requiring tighter manufacturing tolerances or increased device complexity.
Data Source
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AI summary
Uneven wear is cited as a main cause of degradation of the individual parts of a syringe pump. Syringe pumps are composed of numerous parts, and differences between individual parts, cutters, and so on will lead to deviations that occur when driving and result in uneven wear. Specifically, a seal piece composed of a soft material is easily damaged by uneven wear. In order to solve the above-described problem, the present invention provides an automatic analysis device that comprises a dispensing unit that aspirates and dispenses a liquid, and a syringe pump that feeds and aspirates a liquid into and from the dispensing unit, wherein the automatic analysis device is characterized: in that the syringe pump comprises a syringe tube that can store a liquid, a plunger that can move up and down in the length direction of the syringe tube, a plunger upper pressing component that contacts the plunger, a motive force transmitting part that transmits motive force to the plunger via the plunger upper pressing component, and a plunger lower pressing component that contacts the motive force transmitting part; and in that the plunger upper pressing component and the motive force transmitting part make point contact with each other, and the motive force transmitting part and the plunger lower pressing component make point contact with each other.