Double-acting piston pump pressure drop compensation

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Solution Overview

Problem

Double-acting piston pumps experience pressure drops during reversal points, affecting the quality of flowable medium application, particularly with heated adhesives, due to the time required for pneumatic valve switching and differing designs of check valves, leading to constrictions in the application pattern.

Innovation Solution

The direction of piston movement is reversed during interruption periods, allowing sufficient time for pressure recovery before resuming dispensing, and a pressure accumulator can be used to compensate for pressure drops, with a leaky piston design to minimize wear and optimize operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the piston direction is reversed at the reversal points to maintain continuous pumping action, then the pumping continuity is improved, but the pressure drop during reversal affects the application pattern quality

Engineering Contradiction:

Improvepumping continuityVSAvoidapplication pattern quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The control device reverses the piston direction in advance during interruption periods before the actual dispensing begins. This preliminary reversal action ensures that pressure recovery is complete before the dispensing phase starts, eliminating constrictions in the application pattern while maintaining continuous pumping capability.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If pneumatic changeover valves are used to reverse piston direction, then the reversal mechanism is simplified, but the valve switching time causes pressure drop

Engineering Contradiction:

Improvereversal mechanism simplicityVSAvoidvalve switching time

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The patent converts the harmful effect of valve switching time by scheduling reversals to occur during interruption periods when no dispensing is occurring. The pressure drop during valve switching is no longer harmful because it happens when the system is already in an interruption phase, transforming a detrimental time loss into a non-critical period.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of manufacture

If check valves are designed with movable balls for vertical piston operation, then the valve design is simplified, but the ball movement time causes volume flow loss

Engineering Contradiction:

Improvecheck valve design simplicityVSAvoidvolume flow loss

Core Design Contradiction:

Ease of manufactureVSLoss of substance

Solution Approach 1:

The control device anticipates and executes piston direction reversal during interruption periods before the dispensing phase begins. This preliminary action allows the check valve balls to complete their movement and sealing operations during the interruption period, preventing volume flow losses during the actual dispensing operation.

Inventive Principle:

Principle #10Preliminary action

4Reliability

If pressure accumulator is used to compensate for pressure drops, then the pressure compensation is improved, but the accumulator can only be optimally designed for one operating state

Engineering Contradiction:

Improvepressure compensationVSAvoidoperating state flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent replaces the mechanical pressure accumulator system with a control-based solution that uses the control device to reverse piston direction during interruption periods. This substitution eliminates the need for a pressure accumulator while achieving better pressure stability, and the control device can adapt to different operating conditions without requiring redesign.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 approach reduces the negative impact of pressure drops on the application pattern, ensuring consistent flow and minimizing constrictions in the applied adhesive bead, thereby improving the quality and reliability of the application process.

Implementation Method 1

a pressure accumulator can be used to compensate for pressure drops

Methodology Applied

Scientific EffectPressure accumulation: Accumulator (energy)

Data Source

PatentEP4219942B1Double-acting piston pump, and application system for applying a flowable medium to a substrate

Publication Date: 2024.11.27 ROBATECH

Figure 1
Figure 2~4
Figure 5~6

AI summary

Double-acting piston pump for conveying a flowable medium to a dispensing device (5), wherein the piston pump (1) has a piston (4) movable between a first reversal point (24) and a second reversal point (25), for conveying the flowable medium, wherein the piston pump (1) has a control device for controlling the direction of movement of the piston (4), wherein the control device is configured to reverse the direction of movement of the piston (4) when the respective reversal point (24, 25) is reached, wherein the piston pump (1) has a measuring device for measuring a piston speed, wherein the control device is configured to reverse the direction of movement of the piston (4) when a certain speed value of the measured piston speed is undershot.