Lubricant Dispenser Back-EMF Stroke Control
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Solution Overview
Problem
Existing lubricant dispensers face challenges in achieving precise metering due to deviations in plunger stroke, leading to inefficient lubricant consumption or insufficient lubrication, and current solutions with elaborate sensors are costly, bulky, and prone to external disturbances.
Innovation Solution
A method using a microcontroller-operated direct-current drive motor with monitored motor current and voltage, calculating motor runtime based on characteristics like armature resistance and magnetic field intensity, and employing pulse-width modulation for precise voltage control, allowing for adjustable dispensing intervals and temperature compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If elaborate sensors are used to record plunger stroke or spindle rotations, then measurement precision is improved, but device complexity increases and cost increases
Solution Approach 1:
The motor serves itself by providing back-EMF voltage that directly indicates its operating state. The control unit uses this self-generated signal to calculate plunger stroke without external sensors, making the motor both the actuator and the measurement source.
Solution Approach 2:
The patent replaces mechanical sensor systems with an electrical measurement approach. Instead of using mechanical encoders or position sensors on the spindle, the system uses electrical voltage measurements from the motor's back-EMF to infer mechanical position and stroke.
2Measurement precision
If elaborate sensors are used to record plunger stroke or spindle rotations, then measurement precision is improved, but susceptibility to external disturbances increases
Solution Approach 1:
The motor provides its own measurement signal through back-EMF voltage, eliminating the need for external sensors that could be affected by dust, moisture, or electromagnetic interference. The measurement signal is generated internally within the motor structure.
Solution Approach 2:
The back-EMF voltage acts as an intermediary signal that indirectly reflects the motor's mechanical state without requiring direct mechanical contact or external sensing elements that could be disturbed by the environment.
3Manufacturing precision
If motor runtime is extended to achieve predetermined plunger stroke, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The system dynamically adjusts motor runtime based on real-time calculations of actual plunger stroke. Instead of using a fixed, conservative runtime that ensures precision but reduces speed, the system calculates the exact runtime needed for each dispensing cycle based on measured stroke characteristics.
Solution Approach 2:
The control unit uses feedback from back-EMF voltage measurements to calculate actual plunger stroke and adjust motor runtime accordingly. This closed-loop approach allows the system to maintain precision while optimizing dispensing speed for each specific operation.
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 enables precise and cost-effective lubricant dosing with reduced complexity and cost, ensuring efficient lubrication while preventing bearing damage, and is adaptable to different lubricant cartridges with varying sizes.
Implementation Method 1
a direct-current drive motor for moving the plunger
Implementation Method 2
the back electromotive force (back-EMF) voltage generated by the motor during its operation is monitored
Data Source
AI summary
The invention relates to a method of dosing lubricating grease with a lubricant dispenser (1), comprising a lubricant cartridge (3) filled with lubricating grease (2) and holding a plunger (4) for expelling the lubricating grease (2), a spindle (6) driven by a direct-current drive motor (5) for moving the plunger (4), a power supply (7), a controller (8) for operating the motor (5) with a microcontroller (9), and a device (10) for interrupting the motor current flowing through the motor (5). The motor (5) is started up by the controller (8) in adjustable time intervals and a dose of dispensed agent is expressed from the cartridge (3) through a plunger motion with a predetermined plunger stroke. The motor current and the motor voltage are measured during motor operation, and the motor runtime, and the plunger stroke is calculated with the current and voltage measured values and at least one motor characteristic. The motor current is interrupted when the motor operating time reaches the calculated motor runtime.