Hand Protection Lever Control for Compact Chain Saw Operation

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Solution Overview

Problem

Existing handheld power tools lack a compact, precise, and user-friendly mechanism for controlling the movement of the hand protection lever, which is crucial for safety and operational efficiency.

Innovation Solution

A mechanical control unit with a control element that allows for axial relative movement between the control element and the hand protection lever, enabling precise and adjustable control of the lever's movement, integrated in a space-saving design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a mechanical control unit is added to control the hand protection lever movement, then the precision and comfort of lever control is improved, but the device complexity increases

Engineering Contradiction:

Improvemovement control precisionVSAvoidcontrol unit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The control unit is segmented into distinct functional components: a control element with control surfaces, a hand protection lever, and a actuating element. Each component has a specific function, allowing precise control while maintaining modularity and manageable complexity. The control element can be separately assembled and adjusted.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The control system incorporates adjustable elements that allow the control characteristics to be modified. The control element can be positioned at different locations, and the control surfaces can be adjusted to change the force requirements and movement characteristics of the hand protection lever, providing adaptability without increasing fundamental complexity.

Inventive Principle:

Principle #15Dynamics

2Volume of moving object

If the control element is disposed close to the hand protection lever for space-saving design, then the device volume is reduced, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvecontrol unit volumeVSAvoidcomponent positioning precision

Core Design Contradiction:

Volume of moving objectVSManufacturing precision

Solution Approach 1:

The control element is designed as a separate, modular component with defined mounting features. This segmentation allows for standardized manufacturing and assembly, reducing the need for high-precision custom fitting while enabling compact arrangement close to the hand protection lever.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The design allows for adjustment of the control element's position and orientation parameters. By providing adjustable mounting arrangements and configurable control surface geometries, the system can achieve precise control functionality through parameter optimization rather than requiring extremely tight manufacturing tolerances.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If the control element is made adjustable for flexible control, then the adaptability is improved, but the device complexity increases

Engineering Contradiction:

Improvecontrol flexibilityVSAvoidadjustment mechanism complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The control element is designed with multi-functionality, serving both as a positioning component and as a force transmission element. The same control surfaces that define the movement path also provide the mechanical advantage for force application. This universal design provides flexibility without requiring separate adjustment mechanisms for each function.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

Inventive Principle:

Principle #15Dynamics

4Ease of manufacture

If the axial relative movement mechanism is used for controlling the lever, then the manufacturing simplicity is improved, but the control precision may be reduced

Engineering Contradiction:

Improvecontrol unit manufacturing simplicityVSAvoidlever movement control precision

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The control mechanism converts axial linear movement into rotational movement of the hand protection lever through the geometric relationship between the control surfaces and the lever. This dimensional transformation allows simple linear actuation to produce precise angular positioning through the mechanical geometry of the control surfaces, achieving both manufacturing simplicity and control precision.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS20260102939A1Hand-Held Power Tool and Hand-Held Power Tool Device

Publication Date: 2026.04.16 ROBERT BOSCH GMBH

AI summary

A handheld power tool, in particular a chain saw, includes (i) a hand protection lever, and (ii) at least one mechanical control unit for controlling the movement of the hand protection lever of the handheld power tool. The control unit includes at least one mechanical control element provided to control rotational movement of the hand protection lever by an axial relative movement between the control element and the hand protection lever.