Dosing Pump Piston Control for Soft Stop
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Solution Overview
Problem
Metering pumps used in vehicle heaters experience abrupt stops, leading to undesirable noise and vibrations, which cannot be mitigated without compromising fluid delivery volume or movement frequency.
Innovation Solution
A method that adjusts the voltage application to control the piston's movement frequency and end position, using current monitoring to determine when the piston reaches the end position and adjusting the pulse duty factor to ensure a softer stop without affecting the fluid delivery volume, by comparing the reaching time with a reference and shifting it if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If voltage is applied to move the piston quickly to the end position, then productivity is improved, but noise and vibrations increase due to abrupt stops
Solution Approach 1:
The voltage is applied in periodic pulse intervals rather than continuously, allowing the piston to be accelerated quickly during the pulse and then decelerate naturally before the next pulse, reducing impact noise while maintaining high movement frequency
Solution Approach 2:
The voltage is applied before the piston actually reaches the end position, based on predetermined timing calculations, so that the piston is already decelerating by the time it approaches the stop, preventing abrupt impacts
2Object-generated harmful factors
If voltage is applied for a shorter time to avoid the stop, then noise and vibrations are reduced, but the fluid delivery volume decreases
Solution Approach 1:
The system monitors the actual piston movement time and compares it with the predetermined reference time, then adjusts the voltage pulse duration accordingly to maintain both soft stopping and adequate fluid delivery volume
Solution Approach 2:
The voltage pulse parameters (duration, amplitude) are dynamically adjusted based on the measured piston movement characteristics, allowing optimization of both noise reduction and fluid delivery volume
3Measurement precision
If additional sensors are added to monitor piston position, then control precision is improved, but device complexity increases
Solution Approach 1:
The system uses its own electrical characteristics (current consumption, voltage drops) to infer piston position and movement state, eliminating the need for external sensors while maintaining control precision
Solution Approach 2:
The existing electrical components (power supply, control circuitry) perform multiple functions including both actuation and sensing, avoiding additional hardware complexity
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
Reduces noise and vibrations by ensuring a controlled stop while maintaining the desired fluid volume and movement frequency, without the need for additional sensors.
Implementation Method 1
a drive unit associated therewith that can be electrically excited by applying a voltage
Data Source
Figure 1
Figure 2a~2c
Figure 3~4
AI summary
The method involves creating a voltage for moving a piston (20) in a direction to an end position during excitation time interval. The time point determined during the interval is compared with a reference. A changed voltage for shifting the time point in the direction to the predetermined reference is created, if the distance of the time point to the reference lies over a predetermined threshold.