Handheld Tool Switching Mechanism for Continuous Operation
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Solution Overview
Problem
Existing electric handheld machine tools require interruption of the work process to switch between functional ranges, such as drilling and percussion drilling, due to the need to adjust additional operating elements with a separate hand.
Innovation Solution
A pushbutton switch element integrated into the motor switching element allows for mechanical switching between functional ranges without interrupting the work process, using a spring-based displacement resistance to signal the transition and ensure seamless return to the original state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional operating elements are added to switch between functional ranges (drilling, percussion drilling), then the machine tool can perform more functions, but the operator must interrupt work and use the other hand to adjust, reducing ease of operation
Solution Approach 1:
The patent combines the motor switching element and the mechanical additional function switching element into a single integrated operating element. This allows the operator to control both motor current and mechanical functions (drilling, percussion drilling, rotary blow) through one component, eliminating the need for separate control elements and maintaining continuous operation.
Solution Approach 2:
The single operating element serves multiple functions: it controls motor current in the first functional range and switches between different mechanical operating modes (drilling, percussion drilling, rotary blow) in the second functional range. This multi-functionality reduces the number of components needed and simplifies the control interface.
2Ease of operation
If a single operating element controls both motor current and mechanical additional functions, then operation continuity is maintained, but the device complexity increases
Solution Approach 1:
The operating element is designed with dynamic characteristics, including a pushbutton switch element that can be pressed to different depths and a spring mechanism that provides variable displacement resistance. The spring creates different force thresholds that trigger different functions, allowing complex behavior to emerge from a relatively simple mechanical structure.
Solution Approach 2:
The spring mechanism acts as an intermediary between the operator's input force and the switching mechanisms. It provides a smooth transition between functional ranges and creates haptic feedback signals, mediating the interaction between the operator and the complex internal switching mechanisms without requiring the operator to directly engage with multiple separate controls.
3Ease of operation
If the pushbutton switch element requires increased displacement resistance to switch functional ranges, then functional switching is clear and controlled, but the force required to operate increases
Solution Approach 1:
The spring mechanism creates periodic or staged resistance during the pushbutton's travel. Instead of a single high-force threshold, the spring provides gradually increasing resistance that creates distinct phases of operation, allowing the operator to sense transitions between functional ranges through haptic feedback while distributing the force requirement across the entire stroke rather than concentrating it at a single point.
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
Enables continuous operation by allowing the operator to switch between functional ranges, like drilling and percussion drilling, without pausing the tool, through a single operating element, enhancing usability and efficiency.
Implementation Method 1
using a spring-based displacement resistance to signal the transition and ensure seamless return to the original state
Data Source
AI summary
An electric handheld machine tool includes: a tool spindle driven by an electric motor; a gearing situated between the tool spindle and the electric motor; and a manually adjustable operating element which has an adjustment travel, the adjustment travel having at least two functional ranges. Upon switching over from a first functional range to a second functional range, a mechanical additional function of the gearing is mechanically connected. The operating element is configured as a part of a motor switching element for influencing the current through the electric motor.