# 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. - **Patent:** US RE48399 - **Original title:** USRE48399E1 - Distributed winding arrangement for an electric motor - **Owner:** Black and Decker Inc - **Granted:** 2021 - **Status:** Active - **Times cited:** 0 - **Field:** consumer_electronics, mechanical ## What it does 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. ## 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. ## 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. ## Real-world examples 1. Cordless power drills 2. Electric impact drivers 3. Handheld power saws ## Why it matters 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. ## 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. **Full plain-English explainer:** https://patentbrief.org/patent/us/RE48399/action-camera-waterproof-housing **Original patent:** https://patents.google.com/patent/USRE48399 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How a Single Coil Powers Multiple Motor Armatures Simultaneously](https://patentbrief.org/patent/us/3723796/mri-cancer-tissue-detection) — A 1973 design for an electric motor that uses a single central coil to power several separate armatures arranged in a circle. - [How a Sealed Electric Motor Stays Cool Inside](https://patentbrief.org/patent/us/12734871/sealed-motor-with-internal-cooling-features) — This patent describes a brushless direct-current (BLDC) motor sealed in an airtight compartment that uses openings in its spinning rotor to create an internal airflow, cooling the motor by transferring heat to the end caps. - [How Nikola Tesla Invented the Modern AC Electric Motor](https://patentbrief.org/patent/us/382280/tesla-ac-motor) — Nikola Tesla's 1888 patent for an induction motor that uses rotating magnetic fields to convert electricity into mechanical motion without needing physical brushes. - [How Electric Power Systems Run Industrial Fracturing Equipment](https://patentbrief.org/patent/us/12735969/electrically-driven-fracturing-system) — This patent describes an electrical power system for fracturing equipment, using separate high-voltage and low-voltage generators and switches to efficiently power a main motor and its auxiliary devices. - [How Automatic Rotating Curling Irons Capture and Wind Hair](https://patentbrief.org/patent/us/RE48170/airwrap-styler) — A motorized hair styling tool that uses a rotating ring with tabs to automatically catch and wrap hair around a heated barrel.