Threaded Motor-to-Gearbox Connection for Compact Geared Motors

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Solution Overview

Problem

Existing three-phase geared motors face challenges in achieving a compact size and variability in combining different electric motors with gears due to limitations in connection methods, such as screw connections that increase installation space and impair motor function, and require a flexible attachment to accommodate terminal box access.

Innovation Solution

A threaded connection between the transmission-side connecting device and the bearing plate using internal and external threads that surround the recesses, allowing for axial limitation and multiple thread starts for variable positioning, enabling a compact design without exceeding the motor and gear dimensions, and providing a sealing function.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If screw connections are used to connect the transmission housing to the bearing plate, then the connection is secure, but the installation space increases and the motor function may be impaired

Engineering Contradiction:
Improveconnection strengthVSAvoidinstallation space
Core Design Contradiction:
StrengthVSArea of stationary object

Solution Approach 1:

The threaded connection allows the bearing plate to be nested within the transmission housing structure. The external thread on the bearing plate engages with the internal thread in the transmission housing, creating a compact integrated assembly where components are nested together rather than requiring separate mounting space for screw holes and fasteners.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The connecting device is merged with either the transmission housing or an intermediate flange, eliminating the need for separate connection elements. The threaded connection integrates the bearing plate and transmission housing into a unified structure, reducing the overall installation footprint while maintaining secure connection.

Inventive Principle:
Principle #5Merging (Combining)

2Ease of operation

If bores are arranged outside the stator for screw access, then the connection is accessible, but the installation space increases beyond what is forced by the motor and gear itself

Engineering Contradiction:
Improveconnection accessibilityVSAvoidinstallation space
Core Design Contradiction:
Ease of operationVSArea of stationary object

Solution Approach 1:

Instead of arranging bores outside the stator for accessibility, the invention inverts the approach by providing threaded connections that surround the recess in the bearing plate. The threading allows connection from the motor side without requiring external bore access, maintaining accessibility while minimizing installation space.

Inventive Principle:
Principle #13The other way round (Inversion)

3Ease of manufacture

If an intermediate flange with tapered neck is used for screwing, then the connection is achieved, but the axial size becomes fairly large

Engineering Contradiction:
Improveconnection feasibilityVSAvoidaxial size
Core Design Contradiction:
Ease of manufactureVSLength of moving object

Solution Approach 1:

The invention extracts the unnecessary tapered neck portion from the intermediate flange design. By providing direct threaded connections on the bearing plate and transmission housing, the solution eliminates the axial space consumed by the tapered neck while maintaining the feasibility of the screwing connection.

Inventive Principle:
Principle #2Taking out (Extraction)

4Ease of manufacture

If through-holes are designed for screw connection, then the connection is achieved, but sealing becomes problematic

Engineering Contradiction:
Improveconnection feasibilityVSAvoidsealing performance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The invention employs sealing elements such as O-rings or sealing films in conjunction with the threaded connection. These flexible sealing components fit within the threaded connection structure, providing reliable sealing without requiring through-holes that would compromise the seal between the bearing plate and transmission housing.

Inventive Principle:
Principle #30Flexible shells and thin films

Data Source

PatentEP2538526B1Alternating current drive engine and components of same
Publication Date: 2022.05.11 LENZE DRIVES
  • EP2538526B1 patent drawingFigure 1~2
  • EP2538526B1 patent drawingFigure 3a~4

AI summary

The motor (10) has a gear box-side link assembly (70) that enables a connection of a gear housing (22) with an end shield (42) of an electromotor (40) i.e. synchronous motor. A recess (62) is protruded by a driven shaft (48) connected with the gear housing at a gear housing or at an intermediate flange (60). The gear box-side link assembly and the end shield are interconnected by a threaded connection of an internal thread (72) and an external thread (50). The threads surround another recess (46) in the end shield and the former recess in the gear housing and/or in the intermediate flange.