Hollow Motor Drive Offset Magnet and Nut

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Solution Overview

Problem

Existing hollow motor drive devices face challenges in achieving high rigidity and stop-responsiveness while maintaining a compact structure and ease of maintenance, with previous designs either compromising on precision or increasing device size due to complex arrangements and bearing configurations.

Innovation Solution

The hollow motor drive device incorporates a screw shaft with a spiral screw groove, a nut member with a nut groove, and a hollow drive shaft with a permanent magnet, where the nut member and permanent magnet are non-overlapping, and a housing with a bearing and coil portion, allowing for a compact, high-rigidity structure with improved maintenance and adjustable power settings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If bearings are arranged on both sides of the hollow motor for supporting the tubular rotor, then the rotor support stability is improved, but the maintenance performance deteriorates and assembling work becomes complicated

Engineering Contradiction:

Improverotor support stabilityVSAvoidmaintenance performance

Core Design Contradiction:

Stability of the object's compositionVSEase of repair

Solution Approach 1:

The patent divides the bearing support function into two separate locations: one bearing supports the tubular rotor at one end, while another bearing supports the nut member at a different location. This segmentation allows each bearing to be independently accessible for maintenance while providing stable support for both rotating components, resolving the contradiction between stability and maintainability.

Inventive Principle:

Principle #1Segmentation

2Strength

If the hollow motor, ball screw/nut and spline mechanism are arranged in series, then high rigidity is realized, but the device size becomes large

Engineering Contradiction:

Improvedevice rigidityVSAvoiddevice size

Core Design Contradiction:

StrengthVSVolume of moving object

Solution Approach 1:

The patent merges the ball screw/nut mechanism and spline mechanism into a integrated assembly where the nut member contains both the screw engagement portion and spline engagement portion. This merging allows the hollow motor, ball screw/nut and spline mechanism to function together in a compact configuration rather than being arranged in series, achieving high rigidity while minimizing device size.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent employs a nested configuration where the nut member is positioned within the tubular rotor structure, and the spline mechanism is integrated within the nut member. This nesting arrangement allows multiple functional components to occupy overlapping spatial volumes, achieving high rigidity through proper mechanical coupling while keeping the overall device size compact.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Reliability

If a pair of bearings is arranged on both side of the hollow motor, then the rotor support is improved, but the assembling work becomes complicated

Engineering Contradiction:

Improverotor supportVSAvoidassembling work

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent segments the bearing arrangement so that one bearing supports the tubular rotor while another bearing supports the nut member at a different location. This segmentation simplifies the assembling process by allowing bearings to be installed independently at separate access points, while still providing reliable support for both rotating components.

Inventive Principle:

Principle #1Segmentation

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 enhances stop-responsiveness, maintains a compact size, and simplifies maintenance by allowing for easy adjustment and replacement of components, achieving high rigidity and efficient operation.

Implementation Method 1

a permanent magnet, as a field magnetic flux generating source, is disposed on an outer peripheral side of the hollow drive shaft... and a coil portion as a magnetic field generating source

Methodology Applied

Scientific EffectElectromagnetic interaction: Lorentz Force

Implementation Method 2

a screw groove 12a formed in an outer peripheral surface of the screw shaft 12... and a nut groove formed in an inner peripheral surface of the nut member 13 so as to be screw-engaged with the screw groove

Methodology Applied

Scientific EffectScrew mechanism: Screw

Data Source

PatentUS7893582B2Hollow motor drive device with an offset magnet, shaft, and nut

Publication Date: 2011.02.22 THK CO LTD

AI summary

A hollow motor drive device includes a screw shaft provided with a spiral screw groove formed in an outer peripheral surface thereof, a nut member screw-engaged with the screw groove, a hollow drive shaft having an inner peripheral side on which the nut member is fixed and an outer peripheral side on which a permanent magnet is disposed, and a housing provided with a bearing portion rotatably supporting the hollow drive shaft and a coil portion. In the hollow drive shaft, the nut member and the permanent magnet are disposed so as not to be overlapped with each other in a direction perpendicular to the axial direction of the hollow drive shaft, and in the housing, the bearing portion is disposed to a position corresponding to the nut member, and the coil portion is disposed to a position corresponding to the permanent magnet.