Switching Spring Design for Hand Tool Gearbox Assembly
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Solution Overview
Problem
Existing hand-held power tools face challenges in simplifying the assembly of the transmission housing and transmission unit, leading to complex and wear-prone switching mechanisms, which complicate the switching between different gear stages and torque transmission.
Innovation Solution
The design incorporates a switching spring with perpendicularly spaced spring legs for easy assembly, allowing the actuating unit to be positioned for operation during assembly, and features a switching spring that stores energy for low-wear switching between synchronous positions, utilizing a switching bevel for axial movement during rotary operation, and limb areas for efficient movement transmission, reducing component count and enabling direct coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex switching mechanism is used to switch between gear stages, then reliable torque transmission is achieved, but the assembly process becomes complicated and wear increases
Solution Approach 1:
The switching mechanism is divided into modular components: actuating unit with transmission element, switching spring with spring legs, and switching means. These segmented parts can be assembled independently and then combined, simplifying the overall assembly process while maintaining reliable torque transmission through each dedicated component
Solution Approach 2:
The switching spring acts as an intermediary element between the actuating unit and the switching means. It stores energy and transmits the switching motion, mediating the interaction between components to achieve reliable gear stage switching without direct complex mechanical coupling
2Adaptability or versatility
If traditional switching mechanisms are used, then gear stage switching is achieved, but wear on switching components increases
Solution Approach 1:
The switching spring stores energy beforehand and provides cushioning during the switching process. This energy storage and gradual release reduces impact and wear on the switching components, allowing reliable gear stage switching without excessive wear
Solution Approach 2:
The switching mechanism utilizes changes in the spring's deformation parameters (compression/extension) to achieve switching. By changing the physical state of the switching spring rather than relying on direct mechanical engagement, wear is reduced while maintaining switching functionality
3Reliability
If multiple components are used for switching, then reliable operation is achieved, but assembly time and complexity increase
Solution Approach 1:
The actuating unit is merged with the transmission housing, and the switching means is integrated with the transmission unit. This merging of components allows the actuating unit to be pre-assembled and then quickly installed as a unit, reducing overall assembly time while maintaining reliable switching operation through the integrated design
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
This configuration simplifies assembly, reduces wear, and allows for efficient torque transmission with fewer components, enabling smooth switching between gear stages while maintaining structural integrity and operational readiness.
Implementation Method 1
the switching spring forms at least one energy storage means in which a switching force can be stored
Implementation Method 2
at least one spring leg of the switching spring has a switching bevel, against which the transmission element presses during at least one switching process, whereby an axial movement of a switching means connected to the switching spring can be achieved in a structurally simple manner during a rotary movement of the actuating unit
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a hand machine tool, in particular, a hammer drill or chisel, comprising a gearbox housing (12) and a gearbox unit (14) with a switching device (16), comprising a switching spring (18) and an operating unit (20) which may be mounted in the gearbox housing (12) with a transfer element (22). According to the invention, the switching spring (18) has a housing region (24) provided for housing the transfer element (22) of the assembled operating unit (20), on assembly of the gearbox housing (12) and the gearbox unit (14).