Brush Holder Choke Coil Layout for Low-Noise Power Tools
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Known hammer drills generate noise due to electromagnetic interference (EMI) caused by commutation in electric motors.
Innovation Solution
Incorporation of a choke coil and a brush holder unit with specific configurations to minimize noise generation, including a stationary housing, contact rails, a movable housing, and terminals that ensure reliable electrical connections and reduce EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a conventional electric motor with commutator and brushes is used, then the power tool achieves functional operation, but electromagnetic interference noise is generated
Solution Approach 1:
A choke coil is introduced as an intermediary component in the electrical circuit between the field coil and brush. This choke coil acts as a mediator that suppresses electromagnetic interference noise while allowing the motor to maintain its functional operation, thus resolving the contradiction between noise reduction and operational reliability
Solution Approach 2:
The harmful electromagnetic interference component is extracted and isolated from the main circuit through the choke coil, which separates the noise generation mechanism from the functional power transmission path, allowing the motor to operate reliably while the noise is filtered out
2Object-generated harmful factors
If a choke coil is added to reduce electromagnetic interference, then noise generation is reduced, but device complexity increases
Solution Approach 1:
The choke coil is integrated into the existing motor structure by combining it with the field coil and brush assembly. This merging approach allows the noise reduction function to be added without creating a completely separate system, thereby minimizing the increase in device complexity while still achieving effective electromagnetic interference suppression
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 power tool is less likely to generate noise, improving operational silence and efficiency.
Implementation Method 1
Known hammer drills generate noise from electromagnetic interference (EMI) caused by, for example, commutation in electric motors
Implementation Method 2
a choke coil configured to electrically connect the field coil and the brush
Data Source
AI summary
A power tool is less likely to generate noise. A power tool includes a housing, a field fixed to the housing and including a field coil, an armature rotatable relative to the field and including a commutator, two brushes that come in contact with the commutator, and a brush holder unit holding the two brushes. The brush holder unit includes two contact rails electrically connectable to the field coil, two first terminals that each come in contact with either of the two contact rails, two second terminals each electrically connectable to a corresponding brush of the two brushes, and a choke coil located between at least one of the two first terminals and at least one of the two second terminals.