Trigger Switch Venting via Filtered Rib for Electric Tools

Solution Overview

Problem

Conventional dust-resistant and water-resistant structures for trigger switches in electric tools often compromise manipulation performance due to increased air resistance and susceptibility to dust and water invasion, particularly when ultrasonic welding is used for sealing.

Innovation Solution

A trigger switch design that incorporates a filter covering ventholes in the housing, either on the outer or inner surface, to maintain dust and water resistance while ensuring proper ventilation and smooth operation, using microfilters with specific pore sizes to allow water vapor passage while blocking rainwater, and utilizing micro-porous elastic bodies for easy assembly and enhanced properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the bonding surfaces of the covers are sealed by ultrasonic welding, then the water-resistant property and dust-resistant property are improved, but the air resistance is increased and manipulation feeling deteriorates

Engineering Contradiction:

Improvewater-resistant propertyVSAvoidmanipulation feeling

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The housing is divided into multiple covers that are selectively bonded, with ventholes provided in at least one cover to allow air passage. This segmentation allows the housing to have both sealed regions (for dust and water resistance) and vented regions (for air flow and manipulation feeling).

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A filter is introduced as an intermediary component in the ventholes to prevent dust and water from entering through the vent openings while allowing air to pass through. This filter mediates between the need for air flow and the need for dust/water protection.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the bonding surfaces of the covers are sealed by ultrasonic welding, then the dust-resistant property is improved, but the air resistance is increased

Engineering Contradiction:

Improvedust-resistant propertyVSAvoidair resistance

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The housing is divided into multiple covers that are selectively bonded, with ventholes provided in at least one cover to allow air passage. This segmentation allows the housing to have both sealed regions (for dust and water resistance) and vented regions (for air flow and manipulation feeling).

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A filter is introduced as an intermediary component in the ventholes to prevent dust and water from entering through the vent openings while allowing air to pass through. This filter mediates between the need for air flow and the need for dust/water protection.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If micro-grooves are provided in the case surface for dust resistance, then the dust-resistant property is improved, but dust and water easily invade through the micro-grooves by pumping action

Engineering Contradiction:

Improvedust-resistant propertyVSAvoiddust and water invasion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A filter is introduced as an intermediary component in the ventholes to prevent dust and water from entering through the vent openings while allowing air to pass through. This filter mediates between the need for air flow and the need for dust/water protection.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The filter uses porous material structure with specific pore sizes that allow air molecules to pass through while blocking larger dust particles and water droplets, utilizing the size difference between gas molecules and liquid/solid particles.

Inventive Principle:

Principle #31Porous materials

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 effectively secures dust and water resistance while maintaining optimal manipulation performance by allowing internal air to vent smoothly, preventing dust and water invasion, and improving the overall feel of the trigger switch during use.

Implementation Method 1

the filter may be a microfilter having micro-holes of 0.1 μm to 10 μm through which water vapor (diameter of 0.0004 μm) is passed while rainwater (100 μm to 3000 μm) is not passed

Methodology Applied

Scientific EffectMicro-hole filtration: Filter (physical)

Implementation Method 2

the internal air is smoothly vented by piston action caused by the reciprocating movement of the trigger

Methodology Applied

Scientific EffectPiston action:

Implementation Method 3

bonding surfaces of covers constituting a housing are sealed by ultrasonic welding

Methodology Applied

Scientific EffectUltrasonic welding: Ultrasonic Vibration

Data Source

PatentUS8550181B2Trigger switch and electric tool provided therewith

Publication Date: 2013.10.08 OMRON CORP

AI summary

An electric tool has a rib projecting from an inner peripheral surface of the electric tool, and a trigger switch. The trigger switch has a housing having a housing venthole, a contact mechanism disposed in the housing, and a trigger that, when depressed into the housing, drives the contact mechanism. The housing of the trigger switch is bonded to the rib. The rib has a rib venthole. The housing venthole is communicated with the rib venthole. The rib venthole is covered with a filter.