Contactless Trigger Switch Using Inductive Coil Assembly
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Solution Overview
Problem
Conventional trigger switches in power tools and similar devices are prone to reliability issues due to dust, vibration, and moisture, requiring complex assembly processes and lubrication, which leads to increased manufacturing complexity and potential failure points.
Innovation Solution
A contactless trigger switch design using a transmitter coil and multiple receiver coils, including sine and cosine coils, to operate in low power mode for on-off switching and inductive position sensing, replacing traditional contacting switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional contacting trigger switches are used, then the device can perform switching functions, but the reliability deteriorates due to dust, vibration, and moisture
Solution Approach 1:
The patent replaces the mechanical contacting switch system with an inductive sensing system using transmitter and receiver coils. The transmitter coil generates a magnetic field that induces current in the receiver coil, enabling contactless detection of trigger position. This eliminates mechanical contacts that are susceptible to dust, vibration, and moisture, thereby resolving the reliability issue while maintaining switching functionality.
Solution Approach 2:
The patent introduces magnetic field coupling as an intermediary between the trigger actuator and the sensing system. The transmitter coil generates a magnetic field that serves as a mediator to detect trigger position without physical contact. This intermediary magnetic field transmission method protects the sensing system from harmful environmental factors while enabling reliable detection.
2Ease of operation
If conventional contacting switches with encapsulation and lubricants are used, then the switch can operate smoothly, but the manufacturing complexity increases
Solution Approach 1:
The patent replaces the mechanical switch system requiring encapsulation and lubrication with an inductive sensing system. The contactless operation between transmitter and receiver coils eliminates the need for mechanical moving parts, lubricants, and protective encapsulation, thereby reducing manufacturing complexity while maintaining smooth operation.
Solution Approach 2:
The inductive sensing system is inherently self-lubricating and self-protecting. The magnetic field coupling mechanism requires no external lubrication or encapsulation to function, as the electromagnetic interaction occurs through air or non-conductive materials. This self-service characteristic simplifies the overall device structure and reduces assembly complexity.
3Ease of manufacture
If conventional contacting switches are used, then the assembly process can be completed, but additional failure points are introduced
Solution Approach 1:
The patent replaces mechanical contacting components with inductive sensing components that have fewer moving parts and no physical wear interfaces. The transmitter and receiver coils are stationary elements that interact through magnetic fields, eliminating failure points associated with mechanical wear, contact erosion, and lubricant degradation while maintaining assembly feasibility.
4Reliability
If contactless inductive sensing is used, then reliability is improved, but the device complexity increases
Solution Approach 1:
The inductive sensing system is designed to perform multiple functions: trigger detection, position sensing, and switching control. By integrating these functions into a single coil-based system, the patent reduces overall device complexity compared to having separate mechanical switches, position sensors, and control circuits, while maintaining the reliability benefits of contactless operation.
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 reliability and reduces assembly complexity while extending operational lifespan under harsh conditions, ensuring secure device shutdown and motor speed regulation.
Implementation Method 1
a transmitter coil and a plurality of receiver coils for receiving signals induced by a (radio frequency/RF) magnetic field generated by the transmitter coil
Data Source
AI summary
A circuit assembly is provided. The circuit assembly has a transmitter coil and multiple receiver coils for receiving signals induced by a magnetic field generated by the transmitter coil, and also has one or more movable metallic targets for influencing the signals picked up by the receiver coils. The receiver coils has a first receiver coil which is a sine-signal-output receiver coil and a second receiver coil which is a cosine-signal-output receiver coil. The transmitter coil and the first and second receiver coils are displaced from each other to have an open area in which the transmitter coil is present but not the first and second receiver coils, the open area having a predetermined range along a movement path of a first target, such that when the first target moves within the predetermined range, the circuit assembly is operable in a first mode as a low power on-off switch.