Drainage Pump PWM Control for Water Dispenser Flow Matching
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Solution Overview
Problem
There is a mismatch between water inlet flow rate and water outlet flow rate in water dispensing units like domestic showers, which can lead to inefficient drainage, especially when the shower tray is level with the ground or in boats where water needs to be pumped overboard, as existing systems rely solely on an on/off sensor for drainage pumps.
Innovation Solution
A system that includes a microcontroller with a control program to measure water inlet flow rate and adjust the pump's power signal via pulse width modulation (PWM) to equalize the water inlet and outlet flow rates, using flow sensors and a PWM carrier frequency to control the electric motor of the pump, ensuring the pump operates efficiently and effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an on/off sensor is used to control the drainage pump, then the pump can be activated when water flows in, but the pump rate cannot be adjusted to match the inlet flow rate, causing mismatch between water inlet and outlet flow rates
Solution Approach 1:
The system uses flow sensors to detect the inlet water flow rate and feeds this information back to the microcontroller. The microcontroller then adjusts the pump motor speed accordingly to match the inlet flow rate, ensuring that the outlet flow rate equals the inlet flow rate. This closed-loop feedback control resolves the contradiction by enabling dynamic flow rate matching without requiring overly complex control logic.
Solution Approach 2:
The system transitions from a static on/off pump control to a dynamic speed-controlled pump system. The pump motor speed is continuously adjusted based on the measured inlet flow rate, allowing the outlet flow rate to dynamically match the varying inlet flow rate. This dynamic control improves drainage efficiency while keeping the control system manageable through proportional control.
2Productivity
If the pump runs at full speed continuously, then water can be pumped effectively, but power losses and audible noise increase
Solution Approach 1:
The pump motor speed is dynamically adjusted to match the actual water flow requirements. Instead of running at full speed continuously, the pump operates at the minimum necessary speed to handle the inlet flow rate. This dynamic speed control reduces power consumption and minimizes audible noise while maintaining effective water pumping performance.
Solution Approach 2:
The system changes the operating parameters of the pump motor by adjusting its speed according to the measured inlet flow rate. When flow rate is low, the pump operates at lower speed, reducing power loss and noise. When flow rate increases, the pump speed increases accordingly to maintain pumping effectiveness. This parameter adjustment resolves the contradiction between pumping effectiveness and energy loss.
3Loss of energy
If the pump is shut down immediately when inlet flow stops, then energy is saved, but water may remain in the shower tray due to delayed drainage
Solution Approach 1:
The system prepares for potential continued drainage needs by implementing a delay before shutting down the pump after inlet flow stops. This preliminary delay allows the pump to continue operating briefly to clear remaining water from the shower tray, ensuring complete drainage. The delay is optimized to balance energy savings with reliable drainage completion.
Solution Approach 2:
The system provides a buffer period after inlet flow cessation before pump shutdown. This cushioning delay ensures that any residual water in the shower tray has time to drain completely before the pump stops, preventing water accumulation. The delay acts as a protective measure to ensure drainage reliability while minimizing additional energy consumption.
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 solution ensures that the water inlet and outlet flow rates are substantially equalized, preventing inefficiencies in drainage and ensuring effective water management in various scenarios, including wheelchair accessibility and boat drainage, while minimizing audible noise and power losses.
Implementation Method 1
means for measuring the water inlet flow rate of the inlet supply water
Implementation Method 2
means for controlling the rate of the pump comprising means for controlling a power signal to an electric motor for the pump to set a pump rate
Implementation Method 3
controlling a power signal to an electric motor for the pump
Data Source
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AI summary
A system for controlling the rate of a pump (2) on a water drainage outlet (3) of a water dispensing unit. The system comprises means for measuring the water inlet flow rate of an inlet water supply to the water dispensing unit and means for controlling the rate of the pump (2) on the water drainage outlet (3) based on the measured water inlet flow rate.