Fail-Safe Switching with Simulation Mode for Machine Commissioning

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Solution Overview

Problem

Existing safety switching devices complicate the process of defining logical operations and detecting errors, particularly before a machine or machine system is operational, making it difficult to ensure safety during commissioning.

Innovation Solution

A switching device with two operating modes: a 'normal' mode where the control part opens or closes the current path based on input signals, and a 'simulation' mode where the current path is permanently interrupted, allowing the display element to indicate the theoretical operating state without actually switching on the output switching element, facilitating error detection and safe commissioning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the switching device operates in normal mode with active output switching elements, then the machine system can be operated, but errors in logical connections cannot be detected before commissioning

Engineering Contradiction:
Improveease of commissioningVSAvoidsafety during commissioning
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The switching device dynamically changes its operating mode between normal operation and simulation mode. In simulation mode, the output switching elements are permanently opened while the display elements continue to reflect the theoretical switching states, allowing error detection without actual machine operation. This dynamic mode switching enables safe commissioning by decoupling the display function from the actual output function temporarily.

Inventive Principle:
Principle #15Dynamics

2Reliability

If the current path is permanently interrupted in simulation mode, then safety is ensured during testing, but the output switching element cannot be tested in actual operation

Engineering Contradiction:
Improvesafety during commissioningVSAvoidtesting capability
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The display elements create a visual copy or representation of the theoretical switching states that would occur if the output switching elements were active. This allows users to test and verify logical connections and detect errors by observing the display states without actually energizing the outputs, thus maintaining safety while providing comprehensive testing capability.

Inventive Principle:
Principle #26Copying

3Adaptability or versatility

If multiple input signals and loads are connected, then the machine system becomes more functional, but defining logical connections becomes more complex and error-prone

Engineering Contradiction:
Improvemachine functionalityVSAvoidconfiguration complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The display elements provide immediate visual feedback about the theoretical switching states resulting from the configured logical connections between input signals and loads. This feedback mechanism allows users to verify their configuration logic in real-time during commissioning, making it easier to detect and correct errors in complex logical connections without having to trace through multiple signals and loads manually.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3660597B1Switching device for fail safe switching on and off a dangerous machine system
Publication Date: 2022.06.08 PILZ GMBH & CO KG
  • EP3660597B1 patent drawingFigure 1
  • EP3660597B1 patent drawingFigure 2~3

AI summary

A switching device for switching an electrical load (24a, 24b) on and/or off has an input section (26) for receiving a defined input signal (20), an output section (30) with an output switching element (38, 40, 42, 44) that provides a current path to the electrical load, and a control section that can be operated in a first active operating mode or in a second active operating mode. The control section (28) controls the output switching element (38, 40, 42, 44) depending on the defined input signal (20) in order to close or open the current path. An indicator element (50, 52) assumes a first display state when the control section (28) is in the first active operating mode and the output switching element (38, 40, 42, 44) is in the closed operating state.The indicator element (50, 52) assumes an alternative second display state when the control unit (28) is in the first active operating mode and the output switching element (38, 40, 42, 44) is in the open operating state. In the second active operating mode, the control unit (28) interrupts the current path independently of the defined input signal (20). Depending on the defined input signal (20), the indicator element (50, 52) assumes either the first display state or the alternative second display state in the second operating mode. Preferably, the switching device serves for the fail-safe shutdown of a hazardous machine system (10).