Trigger Switch Bouncing Suppression and Heat Management
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Solution Overview
Problem
Conventional trigger switches in power tools suffer from bouncing when contacts are switched ON/OFF, leading to increased frictional wear, require additional components for LED illumination before motor rotation, and have issues with heat dissipation and dust ingress, which affects performance and durability.
Innovation Solution
A trigger switch design featuring a sliding circuit substrate with a power control unit, motor brake and control element short-circuit unit, and speed control unit, utilizing springs for stable contact maintenance, an auxiliary switch for LED illumination, and a compact heat slinger for uniform heat absorption, along with packing structures to prevent dust entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power switch and short switch are turned ON and OFF using a conventional switch circuit, then the motor can be controlled to rotate, but the switching element remains controllable causing electric potential difference and sparks that increase frictional wear on contacts
Solution Approach 1:
The patent replaces the conventional mechanical switch circuit with a solid-state switching element (MOSFET) controlled by a control circuit. The switching element is turned ON/OFF based on control signals from the control circuit rather than direct mechanical contact, eliminating sparks and frictional wear on contacts while maintaining motor control functionality.
2Illumination intensity
If an auxiliary switch is added to light the LED before the motor rotates, then LED illumination can be achieved independently, but the number of components increases and the tool becomes less compact
Solution Approach 1:
The patent combines the LED control function with the existing power switch and control circuit. The control circuit that already controls the switching element also controls the LED by routing power through the same switching element or integrated control pathways, eliminating the need for a separate auxiliary switch and reducing overall component count.
3Length of moving object
If the trigger switch is made thinner to improve portability, then the tool becomes more compact, but dust-proof protection is compromised due to larger gaps for dust entry
Solution Approach 1:
The patent uses elastic packing members (such as rubber or silicone seals) that can deform to fill gaps between the sliding shaft and support member. These flexible packing members maintain effective dust-proof sealing even when the switch housing is made thinner, allowing the switch to be compact while preserving dust-proof protection.
4Temperature
If the L-shaped heat slinger is used to absorb and radiate heat, then heat dissipation is provided, but heat is radiated in a single direction causing localized temperature rise and unpleasant grip
Solution Approach 1:
The patent changes the heat slinger geometry from an L-shape that radiates heat in one direction to a U-shape or ring-shaped configuration that surrounds the control element. This asymmetric redesign distributes heat radiation in multiple directions, preventing localized temperature concentration and providing more uniform thermal management.
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
The solution suppresses bouncing, extends contact life, allows LED illumination before motor rotation, enhances heat dissipation, and improves vibration resistance and motor brake performance, resulting in a more reliable and compact power tool switch mechanism.
Implementation Method 1
A L-shaped metallic heat slinger with good thermal conductivity is fixedly mounted on the case to form a single unit therewith so as to absorb and radiate the heat generated by the control element
Implementation Method 2
A L-shaped metallic heat slinger with good thermal conductivity is fixedly mounted on the case to form a single unit therewith so as to absorb and radiate the heat generated by the control element
Implementation Method 3
a movable armature having two short-circuit contacts, the movable armature sandwiched and supported by two springs
Data Source
AI summary
To provide a trigger switch having a simple structure that is capable of reducing bouncing when the contacts are switched ON/OFF, the trigger switch includes a switch mechanism integrated in a single assembly a power control unit that turns a plurality of switches provided on the switch mechanism ON/OFF depending on a degree of retraction of the control unit by moving a pressing member over a top of a seesaw-shaped switching bar, a motor brake and control element short-circuit unit that drives a movable armature having two short-circuit contacts and is sandwiched and held between two springs, and a speed control unit that slides a plurality of moving contacts disposed in parallel over sliding contacts disposed on a sliding circuit substrate so as to control both the supply of power and a control element, and thus control the rotation speed of a motor.