Low-Loss Motor Thrust Structure and Soft-Start Drive Circuit

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Solution Overview

Problem

USB power supplies limit power output due to high starting currents of motors, leading to protection cutoffs, and existing motor designs suffer from high friction losses in thrust structures.

Innovation Solution

A low-loss motor design with an arc-shaped or wear-resistant contact interface between the rotating shaft and rear cover, combined with a PWM-controlled drive circuit for soft starts, adjusts current duty cycles to match USB power supply limits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the motor uses a conventional thrust structure with shaft shoulder rubbing against oil-impregnated bearing, then the motor can be manufactured with simple structure, but the friction force is high and motor power loss is large

Engineering Contradiction:

Improvemotor power lossVSAvoidthrust structure complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent applies spheroidality by replacing the conventional flat shaft shoulder contact with a spherical ball contact surface. The ball contact surface is formed on the rotating shaft, and the contact surface on the rear cover is correspondingly shaped to create point contact instead of line contact, significantly reducing friction area and power loss.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent introduces a ball as an intermediary element between the rotating shaft and rear cover. This ball acts as a mediator that transforms the frictional contact into a rolling contact mechanism, reducing direct rubbing and thereby decreasing motor power loss.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the motor uses a conventional thrust structure with large contact area, then the structure is simple and easy to manufacture, but the friction force is high reducing motor efficiency

Engineering Contradiction:

Improvemotor efficiencyVSAvoidthrust structure manufacturing

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Force

If the motor starts with full power, then the motor can provide maximum torque immediately, but the starting current exceeds USB power supply limits causing protection cutoff

Engineering Contradiction:

Improvestarting torqueVSAvoidcontinuous operation reliability

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The patent applies preliminary action by implementing a soft-start control strategy that gradually increases the motor speed from zero to the target speed over a predetermined time period. This preliminary gradual acceleration prevents inrush current spikes that would trigger USB power supply protection, ensuring continuous reliable operation while still achieving the required starting torque.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies dynamics by making the motor speed adjustable and time-dependent during the startup phase. The control system dynamically modifies the motor operating parameters, transitioning from a stationary state through intermediate speed states to the final operating speed, rather than applying full power immediately.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12573970B2Low-loss motor and a drive circuit thereof

Publication Date: 2026.03.10 INTEX MARKETING

AI summary

A low-loss motor may include a casing, a rear cover, and a rotatable shaft. The rotatable shaft may have a first end contacting the rear cover and a second end. An end face of the first end of the rotatable shaft may have a first shape and a contact surface of the rear cover may have a second shape, the second shape being different than the first shape.