Machine Tool Safety Switching Device with Movement-Coupled Actuation

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Solution Overview

Problem

Existing machine tool safety switching devices, particularly hand-held power tools, require multiple components that increase cost, installation space, and weight, while also being vulnerable to dust, moisture, and humidity, and often lack a simple and safe mechanism for activating the motor unit.

Innovation Solution

A machine tool safety switching device with a base body and switching element that are movement-coupled, featuring independent actuating elements which must be actuated simultaneously to activate the motor unit, reducing component count and enhancing resistance to environmental factors through a polished contact surface for low friction and haptic feedback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple separate components are used for the safety switching device, then the reliability and safety can be improved, but the device complexity, cost, and weight increase

Engineering Contradiction:
ImprovesafetyVSAvoidcomponent count
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the base body and second actuating element into a single integrated component. The base body serves dual functions as both the housing structure and the second actuating element, eliminating the need for separate components while maintaining the safety function requiring simultaneous actuation of two elements.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The base body is designed to perform multiple functions: it serves as the protective housing, the second actuating element for safety switching, and the mounting structure for the switching unit. This multi-functionality reduces the overall component count while maintaining reliability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If multiple separate components are used for the safety switching device, then the reliability and safety can be improved, but the installation space and weight increase

Engineering Contradiction:
ImprovesafetyVSAvoiddevice weight
Core Design Contradiction:
ReliabilityVSWeight of stationary object

Solution Approach 1:

By merging the base body and second actuating element into one component, the total weight of the safety switching device is reduced. The integrated design eliminates redundant materials and fasteners while maintaining the structural integrity and safety functionality.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If multiple separate components are used for the safety switching device, then the reliability and safety can be improved, but the resistance to dust and moisture decreases

Engineering Contradiction:
ImprovesafetyVSAvoiddust and moisture resistance
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The integrated base body and second actuating element eliminate gaps and interfaces between separate components, creating a more sealed structure that resists dust and moisture ingress while maintaining the safety switching functionality.

Inventive Principle:
Principle #5Merging (Combining)

4Ease of operation

If the contact surface has high friction, then the haptic feedback is improved, but the actuation force required increases

Engineering Contradiction:
Improvehaptic feedbackVSAvoidactuation force
Core Design Contradiction:
Ease of operationVSForce

Solution Approach 1:

The contact surface is designed with specific local properties - a polished finish that provides appropriate friction for haptic feedback during normal operation, while the overall actuation mechanism is designed to minimize the force required through mechanical advantage and efficient force transmission.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP2455956B1Machine tool safety switching device
Publication Date: 2013.05.22 ROBERT BOSCH GMBH
  • EP2455956B1 patent drawingFigure 1
  • EP2455956B1 patent drawingFigure 2
  • EP2455956B1 patent drawingFigure 3

AI summary

The device has a micro-switch (14) provided with a base portion (16). A movable switching element (18) is located near the base portion. The actuators (20,22) are set for providing joint actuation of the micro-switch in the switched state. The actuator (22) and the base portion of the micro-switch are connected with each other such that the base portion is set in motion when the actuator is operated.