Soap Dispenser PWM Motor Control for Consistent Dose Size
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Solution Overview
Problem
Existing touch-free soap and sanitizer dispensers suffer from inconsistent dose sizes due to factors like battery voltage, manufacturing variances, and pump inefficiencies, leading to overdosing and increased operational costs.
Innovation Solution
The implementation of a dispenser system with a processor, motor, encoder, and pulse width modulation circuitry that precisely controls the motor speed and number of rotations to ensure consistent dose sizes, using a brake to stop the motor after a set number of rotations and employing a stepper motor for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single liquid pump chamber is used to dispense a single shot of liquid, then the dispenser structure is simple, but the dose size becomes inconsistent due to incomplete filling or emptying
Solution Approach 1:
The single liquid pump chamber is divided into multiple pump chambers (first, second, third chambers) that operate in sequence. Each chamber handles a portion of the dispensing cycle, ensuring complete emptying and consistent dosing. The segmentation of the dispensing cycle into multiple strokes with intermediate filling periods resolves the contradiction between structural simplicity and dosing precision.
2Reliability
If the dispense volume is set to a higher volume to ensure minimum dose, then the reliability of minimum dose delivery is improved, but the loss of substance increases due to overdosing
Solution Approach 1:
The system uses sensor feedback to detect when the liquid pump chambers are full and coordinates the operation of multiple chambers to deliver precise doses. The feedback mechanism ensures that dispensing stops at the correct volume, preventing overdosing while guaranteeing minimum dose delivery. This resolves the contradiction by enabling precise control rather than relying on excessive dispensing.
3Ease of operation
If time-based dosing is used where 1 second on time equals one dose, then the ease of operation is improved, but the manufacturing precision deteriorates because battery voltage affects pump motor speed and thus fluid dispensed
Solution Approach 1:
The system replaces time-based dosing with feedback-based dosing using sensors to detect chamber fill levels and motor position. This feedback mechanism compensates for battery voltage variations by monitoring actual dispensing progress rather than relying on fixed time intervals, maintaining precision while preserving ease of operation.
Solution Approach 2:
The system replaces the purely time-based mechanical control with an electronic feedback control system using sensors and processors. This substitution enables precise volume control independent of motor speed variations caused by battery voltage, resolving the contradiction between operational simplicity and dosing accuracy.
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 achieves consistent and precise dispensing of soap or sanitizer, reducing waste and extending the life of refill units by ensuring each dose is accurately controlled, regardless of battery voltage or other environmental factors.
Implementation Method 1
The encoder provides a plurality of signals to the processor for each rotation of the motor. The processor determines the speed of the motor a plurality of times throughout each rotation of the motor.
Implementation Method 2
The pulse width modulation circuitry adjusts the duty cycle to maintain a selected speed.
Implementation Method 3
the processor causes the brake to be applied after a set number of rotations of the motor
Data Source
AI summary
Exemplary power systems for dynamically controlling a dispenser drive motor for dispensing soap, sanitizing or lotion. An exemplary soap, sanitizing or lotion dispenser includes a housing, a receptacle for receiving a container for holding a soap, sanitizing or lotion, a container of soap, sanitizing or lotion and a pump secured to the container. The exemplary soap, sanitizing or lotion dispenser includes a power source, a motor and an actuator that couples the motor to the pump. In addition, the exemplary soap, sanitizing or lotion dispenser includes pulse width modulation circuitry in circuit communication with the power source and the motor. Movement of the actuator one actuation cycle dispenses a dose of soap, sanitizing or lotion. The pulse width modulation circuitry provides a plurality of voltage pulses to the motor to move the actuator one actuation cycle.