Relay Switching Assembly with Dynamic Current Regulation

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Solution Overview

Problem

Relays in safety switching devices are sensitive to shocks and vibrations, leading to unwanted contact openings and increased power dissipation due to higher currents and heat losses, especially in systems with long electrical supply lines.

Innovation Solution

A circuit arrangement with an acceleration sensor and evaluation unit detects external disturbances, dynamically regulating the control current through the relay coil using a PI controller to maintain contact integrity while minimizing power loss, allowing the control current to be reduced by up to 50% when no interference is detected.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the control current is increased to provide high electrical retaining power for shock and vibration resistance, then the relay contact stability is improved, but the power loss and waste heat increase significantly

Engineering Contradiction:
Improverelay contact stabilityVSAvoidpower loss
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies dynamic control of the control current based on detected vibration levels. The evaluation unit monitors vibrations and the current regulator adjusts the control current dynamically - increasing it during vibrations to maintain contact stability, and reducing it during normal operation to minimize power loss. This transforms the static high-current approach into a dynamic adaptive system that resolves the contradiction between reliability and energy efficiency.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements a feedback mechanism where sensor means detect vibrations acting on the relay, the evaluation unit processes this information, and the current regulator adjusts the control current accordingly. This closed-loop feedback system enables the relay to automatically increase retaining power only when vibrations are detected, rather than maintaining high current continuously, thus reducing overall power loss while ensuring contact stability when needed.

Inventive Principle:
Principle #23Feedback

2Loss of energy

If the control current is reduced to minimize power loss, then the waste heat is reduced, but the relay becomes more sensitive to shocks and vibrations causing unwanted contact openings

Engineering Contradiction:
Improvewaste heatVSAvoidsensitivity to shocks and vibrations
Core Design Contradiction:
Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by detecting vibrations before they can cause contact openings and preemptively adjusting the control current. The sensor means and evaluation unit monitor for vibrational disturbances, and when detected, the current regulator increases the control current in advance to counteract the harmful effects of vibrations, preventing contact openings before they occur.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The system dynamically adjusts the control current based on real-time vibration detection rather than maintaining a static low current. This dynamic response allows the relay to operate at low power during normal conditions while automatically increasing retaining power when vibrations are detected, thus minimizing waste heat while protecting against shock and vibration sensitivity.

Inventive Principle:
Principle #15Dynamics

3Reliability

If a high electrical retaining power is maintained continuously to prevent unwanted contact openings during vibrations, then the relay contact integrity is ensured, but the power consumption increases unnecessarily during normal operation

Engineering Contradiction:
Improvecontact integrityVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic monitoring of vibrations through sensor means and evaluation unit, with the current regulator adjusting the control current in periodic cycles based on detected conditions. Instead of continuous high current, the system periodically checks for vibrations and activates high retaining power only during vibration events, reducing overall power consumption while maintaining contact integrity when needed.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The relay system uses its own operational conditions (vibrations) to automatically regulate its control current through the integrated sensor means, evaluation unit, and current regulator. The system self-adjusts its power consumption based on environmental conditions without external intervention, maintaining contact integrity during vibrations while minimizing power consumption during normal operation.

Inventive Principle:
Principle #25Self-service

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 effectively reduces power loss and waste heat in relays by dynamically adjusting the control current based on detected vibrations, ensuring reliable operation while minimizing energy consumption.

Implementation Method 1

the sensor means as an acceleration sensor is designed to detect an acceleration acting on the at least one relay in at least one spatial direction

Methodology Applied
Scientific EffectAcceleration detection: Accelerometer

Implementation Method 2

an electric current flows through the relay coil, which in turn generates a magnetic flow through the ferromagnetic core

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

a relay has a relay coil with a ferromagnetic core connected to a circuit arrangement and can be supplied with a control current

Methodology Applied
Scientific EffectFerromagnetism: Ferromagnetism

Implementation Method 4

The anchor is coupled with a return spring, which is designed to convert the armature to its original position by a spring force when the relay coil is no longer performed by the electrical control current

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 5

a current regulator, which is designed to control the electronic switch, in particular with a pulse width modulation and can control a control current that flows through the relay coil

Methodology Applied
Scientific EffectPulse width modulation:

Implementation Method 6

a shunt resistor 5, which is connected in series to the relay coil 20

Methodology Applied
Scientific EffectElectrical resistance: Electrical Resistance

Data Source

PatentEP3361491B1Switching assembly for operating at least one relay
Publication Date: 2021.11.03 PILZ GMBH & CO KG
  • EP3361491B1 patent drawingFigure 1

AI summary

The invention relates to a circuit arrangement (1) for operating at least one relay (2), comprising: - a power supply device that can provide an operating voltage (3) to the at least one relay (2), wherein an electronic switch (4), a relay coil (20) of the at least one relay (2), and a shunt resistor (5) are electrically connected in series between the operating voltage (3) and ground (GND); and - a current regulator (60) configured to control the electronic switch (4), in particular with pulse width modulation, and to regulate a control current flowing through the relay coil (20); wherein the circuit arrangement (1) comprises at least one sensor element configured to detect shocks, impacts, or vibrations acting on the relay (2); and an evaluation unit (62) for evaluating the sensor data acquired by the sensor element (8).wherein the current controller (60) is configured to regulate the control current based on the sensor data evaluated by the evaluation unit (62).