Handle Device Overload Protection via Force Redirection
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Solution Overview
Problem
Existing handle devices for motor-driven hand tools lack sufficient overload safety, as damping units can be damaged during impact loads, leading to potential detachment and reduced safety.
Innovation Solution
Incorporating an overload protection unit that diverts a significant portion of the force flow to an additional path during overload conditions, using a compact design with a handle base body and damping unit connected in one piece, and featuring flexible elements and a hollow-cylindrical support element to manage force distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring-elastic damping unit is used to transmit damped vibrations to the handle unit, then the operator is decoupled from vibration, but the damping unit can be permanently deformed, overstretched, or cracked by extreme overstretching due to overloads
Solution Approach 1:
The force flow path is segmented into multiple parallel paths: one through the damping unit and another through the overload protection unit. This segmentation allows the system to handle normal vibrations through the damping unit while diverting overload forces through the alternative path, preventing damage to the damping unit.
Solution Approach 2:
The overload protection unit is pre-configured as a backup force flow path that activates before the damping unit can be damaged. The design includes predetermined geometric relationships and material properties that ensure the overload protection unit engages at specific overload thresholds, cushioning the damping unit from extreme forces before permanent deformation can occur.
2Reliability
If an overload protection unit is added to protect the damping unit from damage, then overload safety is improved, but the device complexity increases
Solution Approach 1:
The overload protection unit is merged with the handle base body as an integrally formed component. This combining approach eliminates the need for separate assembly steps and additional fastening elements, reducing overall device complexity while maintaining the dual-force-flow-path functionality for overload protection.
Solution Approach 2:
The handle base body serves multiple functions: it provides structural support for the handle unit, integrates the overload protection unit as a structural feature, and forms part of the mounting connection to the fastening unit. This multi-functionality reduces the total number of components needed in the system.
3Ease of manufacture
If the handle device is designed to be cost-effective and easy to manufacture, then manufacturing simplicity is improved, but overload protection capabilities may be compromised
Solution Approach 1:
The overload protection capability is achieved by changing geometric parameters of existing components rather than adding new materials or complex features. The predetermined geometric relationship between the overload protection unit and damping unit, along with specific material property selections, enables overload diversion through standard manufacturing processes.
Solution Approach 2:
The handle device utilizes composite construction where the handle base body and overload protection unit can be made from materials optimized for their specific functions while being manufactured as an integral piece. This allows selection of cost-effective materials that provide both structural integrity and overload protection without requiring expensive specialized components.
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
Enhances overload safety by redirecting force flow during overload conditions, maintaining tool functionality and user safety while maintaining a cost-effective and easy-to-manufacture design.
Implementation Method 1
The damping unit is designed to transmit at least partially damped vibrations occurring on the fastening unit during an operating state of the handle device or hand tool to the handle unit, so that an operator is at least partially decoupled from the vibration
Implementation Method 2
an overload protection unit is provided which protects the damping unit from damage in the event of an overload condition occurring at the handle unit or at the mounting unit, by diverting at least a portion of the force flow between the mounting unit and the handle unit to an additional force flow path as a bypass in the overload condition
Data Source
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AI summary
The invention relates to a handle device (24; 124), in particular for a hand tool, comprising a grip unit (36; 136) and a fastening unit (30; 130). A resiliently elastic damping unit (32; 132) is arranged between the grip unit (36; 136) and the fastening unit (30; 130), said damping unit (32; 132) being provided to transmit a vibration that occurs on the fastening unit (30; 130) in the operating state of the handle device (24; 124) to the grip unit (36; 136) in an at least partially damped manner, so that a user is decoupled at least partially from the vibration. An overload protection unit (34; 134) is also provided, which protects the damping unit (32; 132) from damage in the event of an overload state occurring on the grip unit (36; 136) or on the fastening unit (30; 130), by at least part of a force flux (80; 180) between the fastening unit (30; 130) and the grip unit (36; 136) being diverted to an additional force flux path (80a, 84; 180a, 184) as a bypass, during the overload state.