How to Make Electric Motors Run Smoother and Last Longer
A design for electric motor armatures that uses a specific ratio of winding slots to commutator bars to reduce electrical sparking and improve motor efficiency.
Original patent title: “USRE48399E1 - Distributed winding arrangement for an electric motor”
A design for electric motor armatures that uses a specific ratio of winding slots to commutator bars to reduce electrical sparking and improve motor efficiency. Granted to Black and Decker Inc in 2021 with 23 claims.
Key facts
Coverage
What does this patent actually cover?
This patent describes a way to arrange the copper wire coils inside an electric motor to make it run more efficiently. By setting the number of commutator bars to be between one and two times the number of winding slots, the motor can better manage the magnetic fields generated during rotation. The design uses a specific overlapping pattern where sub-coils are serially coupled and wound with different turn counts to align the magnetic axis precisely with the commutator bars. This reduces the electrical arcing that typically occurs when the brushes contact the commutator, which helps the motor run cooler and last longer.
The gap
What does this patent NOT cover?
- Does not cover brushless DC motors, as it relies on a commutator and brush system.
- Does not cover motors where the number of commutator bars is exactly double or equal to the number of winding slots.
- Does not cover motor designs that do not use the specific serial sub-coil winding arrangement described in the claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
The innovation lies in the specific ratio of commutator bars to winding slots combined with unequal turn counts in sub-coils, which forces the magnetic axis to align perfectly with the brushes, effectively 'smoothing' the electrical transition.
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Cordless power drills
Electric impact drivers
Handheld power saws
Why it matters
The bigger picture
Electric motors are the heart of power tools, and brush arcing is a primary cause of motor failure and energy loss. By optimizing the winding geometry, this design allows for smaller, more reliable motors in compact tools. It represents a refinement in mechanical engineering that extends the lifespan of high-torque battery-powered equipment.
Filed
August 22, 2018
Granted
January 19, 2021
Market context
Who's building on this
Companies in this space
Black and Decker (Stanley Black & Decker) is the primary assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more → and continues to integrate these motor design principles into their professional and consumer-grade power tool lines. Other major power tool manufacturers like Milwaukee and Makita also focus on similar motor efficiency improvements to maximize battery life.
Market impact
This patent provides a technical advantage in the highly competitive cordless power tool market. By reducing wear and heat, it enables manufacturers to offer longer warranties and more compact tool form factors, which are key selling points for professional contractors.
Claim 1 — Plain English
What this patent covers
This patent describes a way to arrange the copper wire coils inside an electric motor to make it run more efficiently. By setting the number of commutator bars to be between one and two times the number of winding slots, the motor can better manage the magnetic fields generated during rotation. The design uses a specific overlapping pattern where sub-coils are serially coupled and wound with different turn counts to align the magnetic axis precisely with the commutator bars. This reduces the electrical arcing that typically occurs when the brushes contact the commutator, which helps the motor run cooler and last longer.
The clever bit
The innovation lies in the specific ratio of commutator bars to winding slots combined with unequal turn counts in sub-coils, which forces the magnetic axis to align perfectly with the brushes, effectively 'smoothing' the electrical transition.
What it does not cover
- Does not cover brushless DC motors, as it relies on a commutator and brush system.
- Does not cover motors where the number of commutator bars is exactly double or equal to the number of winding slots.
- Does not cover motor designs that do not use the specific serial sub-coil winding arrangement described in the claims.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
PatentBrief Score
Impact Score
Early stage
Citation count
0/40
No citations yet
Claim breadth
15/20
Broad claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
10/20
Granted 5–10 years ago
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$41K – $131K
Midpoint $82K · 12.2 yr remaining · industry ×1.4
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
The original legal language
Original claims
23 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Chen, W., Jr., T. W. F., Fujun, J., & Swaddle, S. (2021). How to Make Electric Motors Run Smoother and Last Longer (U.S. Patent No. RE48,399). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/RE48399/action-camera-waterproof-housing
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How to Make Electric Motors Run Smoother and Last Longer cover?
A design for electric motor armatures that uses a specific ratio of winding slots to commutator bars to reduce electrical sparking and improve motor efficiency.
Who owns patent US RE48399?
Black and Decker Inc owns this patent, granted in 2021.
When does this patent expire?
This patent is expected to expire on January 19, 2041, when the invention enters the public domain.
What problem does this patent solve?
Electric motors are the heart of power tools, and brush arcing is a primary cause of motor failure and energy loss. By optimizing the winding geometry, this design allows for smaller, more reliable motors in compact tools. It represents a refinement in mechanical engineering that extends the lifespan of high-torque battery-powered equipment.
What does this patent NOT cover?
Does not cover brushless DC motors, as it relies on a commutator and brush system.
Patent monitoring