Metering Pump Variable Stroke Speed for Valve Closure
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Solution Overview
Problem
Existing metering pump units face challenges in achieving high metering accuracy when dealing with very small volumes or flow rates, as rapid valve closure is difficult at slow stroke speeds, leading to leakage losses.
Innovation Solution
A metering pump unit with a controlled displacement drive, specifically using a stepper motor or similar electric drive, where the speed and direction of the displacement body can be precisely adjusted to start the pressure stroke with an increased speed for rapid valve closure and then reduce to a lower speed to maintain accurate metering, ensuring reliable valve closure and minimizing leakage losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the stroke speed is reduced to achieve very small volume metering, then the metered volume precision is improved, but the valve closure reliability deteriorates due to insufficient dynamics for rapid valve closure
Solution Approach 1:
The patent applies dynamics by implementing variable stroke speed during the metering process. The displacement body operates at a first, increased stroke speed at the beginning of the pressure stroke to ensure rapid valve closure, then transitions to a second, lower stroke speed for the remainder of the stroke to achieve precise metering of very small volumes. This dynamic speed adjustment resolves the contradiction between valve closure reliability and metering precision.
Solution Approach 2:
The patent changes the speed parameter of the displacement body during operation. By adjusting the stroke speed from a higher initial value to a lower subsequent value, the system optimizes both valve closure performance and metering accuracy. This parameter change allows the system to adapt to different operational requirements within the same metering cycle.
2Reliability
If the stroke speed is increased to ensure rapid valve closure, then the valve closure reliability is improved, but the metering accuracy deteriorates due to excessive flow rate
Solution Approach 1:
The patent uses dynamic speed adjustment where the displacement body operates at different speeds at different phases of the stroke. The increased speed is applied only at the beginning of the pressure stroke when valve closure is critical, then reduced to the lower speed needed for accurate metering. This temporal separation of speed requirements resolves the contradiction.
Solution Approach 2:
The patent applies preliminary action by using the increased stroke speed at the beginning of the pressure stroke to preemptively ensure rapid valve closure before the metering phase begins. This preliminary high-speed action secures reliable valve closure, after which the speed is reduced to achieve precise metering without excessive flow.
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 ensures high metering accuracy even at low delivery flows by ensuring quick and reliable closure of check valves, reducing leakage losses and maintaining consistent dosing accuracy.
Implementation Method 1
A suitable linear actuator is provided to drive the displacement body. For example, this is a rotary drive motor in the form of a stepper motor
Implementation Method 2
The displacement body can change the volume of the metering chamber, thereby achieving a pumping action
Implementation Method 3
Check valves are arranged on the inlet and outlet sides of the metering chamber. During the suction stroke, these valves prevent the pumped medium from flowing back from the pressure line into the metering chamber
Data Source
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AI summary
The invention relates to a metering pump assembly with a metering chamber (16), a displacement body (14) arranged adjacent thereto and movable by a displacement drive (6), and a control device (26) for controlling the displacement drive (6), wherein the control device (26) is designed such that, at least for certain target flow rates to be generated by the metering pump, it controls the displacement drive (6) in such a way that a stroke of the displacement body (14) is started with a first increased stroke speed (n1) and subsequently continued with a second lower stroke speed (n2), and a method for controlling such a metering pump assembly.