Shot Pump Piston Clearance and Porting for Paste Adhesive Metering
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Solution Overview
Problem
Conventional shot pumps face issues with substance remaining and gelation due to dead flow, leakage, and wear, which affect metering performance and lead to maintenance challenges, especially when handling high viscosity materials like paste-like adhesive agents.
Innovation Solution
A shot pump design with a piston and cylinder configuration featuring a clearance ratio of 1/50 to 2 between the piston and cylinder, where the inlet is positioned at the cylinder's tip end and the outlet at the piston's root, allowing for efficient suction and discharge without dead flow, reducing wear, and enabling handling of high viscosity substances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the inlet and outlet are both provided on the bottom portion side of the cylinder facing the tip end of the piston, then the shot pump can discharge substance, but a dead flow portion is formed in the upper portion of the cylinder causing substance to remain and gelate
Solution Approach 1:
The patent repositions the inlet from the bottom portion to the upper portion of the cylinder, and the outlet from the bottom portion to the side face near the small diameter end of the plunger. This spatial redistribution eliminates dead flow portions by ensuring complete substance replacement during piston reciprocation, preventing gelation while maintaining discharge capability.
Solution Approach 2:
The patent inverts the conventional configuration by positioning the inlet at the upper portion opposite to the plunger tip, rather than at the bottom. This inversion ensures that substance flows through the entire cylinder volume during piston movement, eliminating stagnant regions and preventing substance remaining.
2Ease of operation
If the clearance between piston and cylinder is increased to reduce resistance to sucking operation, then sucking becomes easier, but a drift is generated causing insufficient replacement of substance in the cylinder
Solution Approach 1:
The patent optimizes the clearance width between the piston outer periphery and cylinder inner periphery to a specific range (1/100 to 1/10 of the piston outer diameter). This parameter optimization balances the competing requirements: the clearance is sufficient to reduce resistance to sucking operation but small enough to prevent drift and ensure complete substance replacement.
3Productivity
If a gear pump or trochoidal pump is used to transfer paste-like adhesive agent, then transfer is possible, but metering performance deteriorates due to leakage and wearing
Solution Approach 1:
The patent extracts the substance transfer function from contact-based pumping mechanisms (gear pumps, trochoidal pumps) to a non-contact plunger system. The substance is transferred through the clearance between the plunger and cylinder without direct mechanical contact, eliminating wearing and leakage, thereby maintaining shot pump metering precision while achieving paste-like adhesive agent transfer capability.
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 configuration prevents substance remaining and gelation, ensuring constant discharge performance, reducing maintenance needs, and improving handling of high viscosity materials by minimizing resistance and preventing air pockets, thus enhancing product quality.
Implementation Method 1
When a piston provided in a cylinder in the shot pump is raised by a motor drive or a hydraulic drive, a substance to be transferred such as a main agent and a curing agent is sucked into the cylinder. Then, when the piston is lowered, the substance to be transferred is discharged from an outlet.
Data Source
AI summary
A shot pump including a cylinder standing upright and an inlet having a check valve which allows a paste-like transferred substance to only flow into the cylinder therethrough. The shot pump also includes an outlet having a check valve which allows the transferred substance to only flow out of the cylinder therethrough. Additionally, a piston is configured to vertically reciprocate in the cylinder, causing the transferred substance to be sucked from the inlet and then to be discharged from the outlet. The ratio of a clearance between a side face of the piston and an inner side face of the cylinder to an outside diameter of the piston is 1/50 to ½. The transferred substance is sucked from the inlet, is then caused to pass through the clearance between the side face of the piston and the inner side face of the cylinder, and is discharged from the outlet.