Garden Tool Switching Device Magnetic Speed Control
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Solution Overview
Problem
Existing switching devices for garden tools lack a direct and fail-safe mechanism to convert mechanical movements into proportional electrical signals for motor speed control, potentially leading to operator injury and inefficiency.
Innovation Solution
A mechanically coupled conversion unit with a tapping element and spring element, where the speed operating element directly transfers movement to the conversion element, ensuring fail-safe operation and precise signal conversion, and a Bowden cable or potentiometer is used for efficient signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the speed operating element is brought into contact with the conversion element via relative movement to convert mechanical movement into electrical signal, then motor speed control is achieved, but the risk of operator injury increases due to potential mechanical failure
Solution Approach 1:
A magnetic coupling mechanism is introduced as an intermediary between the speed operating element and the conversion element. The magnetic field transfers rotational movement without direct mechanical contact, eliminating the risk of mechanical failure while maintaining functional coupling. This resolves the contradiction by providing reliable signal transmission without the harmful effects of direct mechanical contact.
Solution Approach 2:
The patent replaces the direct mechanical contact system with a magnetic field-based transmission system. The magnetic coupling eliminates mechanical wear, friction, and potential mechanical failure points, thereby improving reliability and eliminating operator injury risks associated with mechanical breakdown.
2Object-affected harmful factors
If the conversion element is arranged at a distance from the speed operating element, then protection against wet conditions is improved, but direct movement transmission becomes difficult
Solution Approach 1:
The magnetic field serves as an intermediary that can transmit rotational movement across a distance without requiring direct mechanical contact. This allows the conversion element to be positioned away from the speed operating element for environmental protection while maintaining functional coupling through magnetic interaction.
Solution Approach 2:
By replacing mechanical transmission with magnetic field transmission, the system can accommodate greater distances between components. The magnetic coupling mechanism provides reliable movement transmission without the complexity of mechanical linkages, gears, or cables that would be required to bridge the gap.
3Device complexity
If a direct mechanical connection is used between speed operating element and conversion element, then movement transmission is simple, but the system lacks fail-safe protection
Solution Approach 1:
The magnetic coupling acts as an intermediary that provides inherent fail-safe protection. If the magnetic coupling fails or becomes misaligned, the motor simply stops receiving speed control signals rather than causing mechanical damage or operator injury. This maintains simplicity while adding safety.
Solution Approach 2:
Replacing direct mechanical connection with magnetic field-based transmission inherently provides fail-safe protection. The magnetic coupling can be designed to disengage safely under failure conditions, preventing the harmful effects associated with direct mechanical connections while maintaining transmission simplicity.
Data Source
Figure 1
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AI summary
The invention relates to a switching device for electrically driveable garden tools, which comprises at least one operating unit to control at least one motor and at least one conversion unit (18) to convert a mechanical movement into a proportional electrical signal; wherein said operating unit (14) comprises at least one switch operating element (54) to actuate at least one electrical switch (66) to open and/or close an electrical circuit, and comprises at least one speed operating element (20) for adjusting a rotation speed of said motor (16). The conversion unit (18) according to the invention comprises at least one conversion element (22) which is mechanically coupled to said speed operating element (20) for converting a mechanical movement of said speed operating element (20) into an electrical signal to adjust a rotation speed of said motor (16).