Direct-Coupled Torque Motor Drive for Zero-Backlash Positioning

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Solution Overview

Problem

Conventional cam-based drive systems for precise positioning are complex, costly, require high power, and suffer from backlash, making them inefficient and difficult to maintain.

Innovation Solution

A direct coupled torque motor is connected to a pinion without intermediate torque transmission devices, with an annular gear mounted on an L-shaped outer race of a bearing, and a simplified mounting plate design that integrates the bearing and motor mount, eliminating the need for a gearbox and transition plate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If cam-based drive systems are used for precise positioning, then positioning precision is achieved, but device complexity increases and backlash occurs

Engineering Contradiction:
Improvepositioning precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent removes the cam mechanism from the positioning system, replacing it with a direct-drive motor connected to a dial plate through a simple gear ratio mechanism. This extraction of the complex cam component eliminates backlash while maintaining positioning precision through direct motor control and geometric relationships between gear teeth.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical cam-based positioning system with an electric motor-driven system. The direct-drive motor eliminates mechanical backlash inherent in cam mechanisms, while the gear ratio provides precise rotational positioning through tooth engagement rather than cam follower contact.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If cam-based drive systems are used for precise positioning, then positioning precision is achieved, but power requirements increase

Engineering Contradiction:
Improvepositioning precisionVSAvoidpower requirements
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

By removing the cam mechanism and its associated high-power actuation requirements, the system reduces power consumption. The direct-drive motor with gear ratio requires less power to achieve the same positioning precision, as it eliminates the mechanical leverage and friction losses inherent in cam-based systems.

Inventive Principle:
Principle #2Taking out (Extraction)

3Measurement precision

If cam-based drive systems are used for precise positioning, then positioning precision is achieved, but manufacturing and maintenance costs increase

Engineering Contradiction:
Improvepositioning precisionVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent eliminates the cam component, which is complex to manufacture and maintain. The replacement motor and gear system uses standard, easily manufactured components with simple geometric relationships, significantly reducing manufacturing and maintenance costs while preserving positioning precision.

Inventive Principle:
Principle #2Taking out (Extraction)

4Device complexity

If direct coupled torque motor is used without intermediate torque transmission devices, then device complexity is reduced, but torque transmission precision may be affected

Engineering Contradiction:
Improvedevice complexityVSAvoidtorque transmission precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces a gear ratio mechanism as an intermediary between the direct-drive motor and the dial plate. This gear ratio provides precise torque transmission through tooth engagement, maintaining accuracy while allowing the motor to operate at optimal speeds and torques, thus reducing overall system complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

This configuration achieves zero backlash, reduced torque requirements, improved efficiency, and lower manufacturing costs while maintaining high precision and durability.

Implementation Method 1

the pinion in direct gearing engagement with the annular gear connected to the second race of the bearing

Methodology Applied
Scientific EffectGear engagement: Gear

Implementation Method 2

providing a bearing between an annular mounting plate and a dial plate

Methodology Applied
Scientific EffectBall bearing: Ball Bearing

Data Source

PatentEP3708871B1Motion control apparatus
Publication Date: 2025.10.22 NEXEN GROUP INC
  • EP3708871B1 patent drawingFigure 1
  • EP3708871B1 patent drawingFigure 2
  • EP3708871B1 patent drawingFigure 3

AI summary

Motion control apparatus (A) includes a direct coupled torque motor (54) slideably receiving an output (50) without other types of torque transmission devices between the output (50) and the motor (54) and between the output (50) and a pinion (7) in direct gearing engagement with an annular gear (44) connected to a second race (32) of a bearing (26) intermediate an annular mounting plate (38) and a dial plate (40). The second race (32) is a single, non-separable piece having L-shaped, radial cross sections to define a mounting pilot for the annular gear (44). The motor (54) is secured to a mount plate (58) having an integral annular spacer (60) extending through a mounting tab (16) and secured to a mount ring (62) adjustably connected to the mounting tab (16) opposite to the mount plate (58).