Ergonomic Switching Unit Pivot Axis for Ratchet Mechanism

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Solution Overview

Problem

Existing portable machine tools, such as angle grinders, lack ergonomic design in their switching units, making it difficult for both right-handers and left-handers to comfortably operate the ratchet elements due to the perpendicular alignment of the release element's pivot axis, which restricts efficient unlocking of the movement lock and affects usability.

Innovation Solution

The design incorporates a pivot axis for the release element that differs from the main direction of movement and longitudinal extent of the ratchet element, allowing for pivotable mounting in two directions, enabling ergonomic operation by aligning the pivot axis with the operator's finger joint axis, and includes a parallelogram bearing unit to maintain consistent orientation and facilitate low switch-on force actuation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the pivot axis of the release element is aligned perpendicular to the main direction of movement of the ratchet element, then the structural design is simplified, but the ergonomic operability is deteriorated

Engineering Contradiction:
Improvestructural designVSAvoidergonomic operability
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

The pivot axis of the release element is deliberately positioned asymmetrically relative to the ratchet element's movement direction. Specifically, the pivot axis is oriented such that it is not perpendicular to the main direction of movement of the ratchet element, creating an asymmetric configuration that aligns with the natural curvature of human fingers (particularly the index finger joint axis), thereby improving ergonomic operability without significantly complicating the overall structure

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The invention applies different geometric relationships to different parts of the switching unit. While the overall structure maintains simplicity, the local arrangement of the release element's pivot axis is specifically optimized to match human finger anatomy, creating a localized improvement in ergonomics at the critical interaction point between the operator's finger and the release element

Inventive Principle:
Principle #3Local quality

2Ease of manufacture

If the pivot axis is aligned perpendicular to the longitudinal extent of the ratchet element, then the manufacturing is simplified, but the ease of unlocking the movement lock is deteriorated

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidease of unlocking
Core Design Contradiction:
Ease of manufactureVSEase of operation

Solution Approach 1:

The invention changes the geometric parameter of the pivot axis orientation from the conventional perpendicular alignment to a non-perpendicular arrangement. This parameter change allows the release element to be actuated more efficiently by the operator's finger, improving the ease of unlocking the movement lock while maintaining manufacturing simplicity through standard machining operations

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If the release element is mounted with a fixed pivot axis, then the structural stability is improved, but the adaptability to different operating hands (right-handed and left-handed) is deteriorated

Engineering Contradiction:
Improvestructural stabilityVSAvoidadaptability to operating hand
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The release element is designed with a pivot axis orientation that serves multiple functions: it provides structural stability as a fixed mounting, while simultaneously being optimized for ergonomic operation by both right-handed and left-handed operators. The non-perpendicular pivot axis configuration creates a universal design that accommodates different hand orientations and operating styles without requiring multiple variants

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

Data Source

PatentEP2607027B1Machine tool with a switch unit and a switch device of a machine tool
Publication Date: 2015.07.29 ROBERT BOSCH GMBH
  • EP2607027B1 patent drawingFigure 1
  • EP2607027B1 patent drawingFigure 2
  • EP2607027B1 patent drawingFigure 3~4

AI summary

The machine tool (10) has a switching unit (14), a movably mounted ratchet element (16). The release element (20) is pivotally mounted on the ratchet element, to release movement lock of the ratchet element. The pivot axis (22) of release element is formed perpendicular to the main movement direction (24) of the ratchet element and perpendicular to the longitudinal direction of the ratchet element.