Pulse Solenoid Control Circuit for PLC Latching
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Solution Overview
Problem
Programmable Logic Controllers (PLCs) and similar devices cannot efficiently control latching solenoids, as they typically require continuous current to both latch ON and latch OFF, leading to excess heat and energy consumption, and are unable to transmit brief voltage signals necessary for latching operations.
Innovation Solution
A pulse solenoid control circuit that generates brief direct current pulses to control latching solenoids, allowing for efficient activation and deactivation by inverting the polarization of the current, reducing power consumption by providing no power between pulses and using timers to control pulse durations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous current is applied to the solenoid coil, then the solenoid valve can be latched ON or OFF, but excess heat is generated and energy consumption increases
Solution Approach 1:
The patent applies periodic pulsed action instead of continuous current. A control circuit generates brief voltage pulses (typically 10-100 milliseconds) to activate the latching solenoid coil. The PLC output module toggles between voltage and zero current in periodic cycles, delivering current only when state changes are needed. This periodic action maintains reliable latching while dramatically reducing energy consumption and heat generation compared to continuous current application.
2Reliability
If continuous current is applied to the solenoid coil, then the solenoid valve can be latched ON or OFF, but excess heat is generated
Solution Approach 1:
The control circuit implements periodic pulsed current delivery with duty cycles typically less than 1%. Current flows through the coil only during brief transition periods (10-100 ms pulses) when state changes are required. Between pulses, the current is interrupted, allowing the coil to cool down. This periodic action maintains reliable solenoid actuation while keeping coil temperature within acceptable limits, preventing overheating and extending component life.
3Ease of operation
If a PLC transmits continuous signal, then the solenoid can be controlled, but unneeded energy expense occurs
Solution Approach 1:
The PLC control system uses periodic pulsed signals instead of continuous output. The control circuit monitors PLC output states and generates voltage pulses only during transitions (rising or falling edges) when latching state changes are needed. During steady states, no current is supplied to the solenoid coil. This approach maintains ease of PLC-based operation while eliminating unnecessary energy expenditure during continuous holding periods.
Solution Approach 2:
The control circuit extracts and eliminates the continuous current component from the control signal, retaining only the essential pulsed transitions needed for latching operations. By removing the continuous current portion and keeping only the brief voltage spikes required for state changes, the system maintains full control functionality while drastically reducing energy consumption during normal 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
The circuit effectively manages latching solenoids with reduced energy expenditure by using brief pulses to toggle the solenoid's state, maintaining position without continuous current, thus minimizing heat and energy usage.
Implementation Method 1
A magnetic draw is present at both the open and closed positions of the coil. The VDC current applied to the coil increases the magnetic draw at the open end thus drawing the piston of the solenoid body towards the upper end of the coil or open position.
Implementation Method 2
By inverting this VDC current the magnetic draw is reversed, thus moving the piston of the relay to the lower or closed position.
Data Source
AI summary
Disclosed herein is a device comprising a pulse trigger switch module configured to generate a first control signal in response to a first input signal value and generate the second control signal in response to a second input signal value. An on pulse generator module provides a first pulse signal having a first predetermined pulse duration in response to the first control signal and an off pulse generator module provides a second pulse signal having a second predetermined pulse duration in response to the second control signal. An on pulse switch module connects a power signal to an output in response to the first pulse signal and an off pulse switch module connects the power signal to the output in response to the second pulse signal.