Drive Train Shaft Locking Mechanism With Spring-Preloaded Engagement

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Solution Overview

Problem

Existing locking mechanisms for vehicle drive trains are not compact, cost-effective, and efficient, particularly in terms of actuating forces required for locking and unlocking.

Innovation Solution

A locking mechanism with a positive locking element that is electrically actuated and pre-tensioned via elastic force transmission means, allowing engagement with a shaft-side complement using a play in the locking area, utilizing a low-force actuator and integrated into the electric motor drive unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a conventional locking mechanism is used, then the shaft can be locked, but the actuating force required is high and the structure is not compact

Engineering Contradiction:
Improveactuating forceVSAvoidlocking mechanism structure
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The positive locking element is pre-tensioned along the shaft by elastic force transmission means (springs) before engagement occurs. This preliminary pre-tensioning action allows the locking element to engage with the shaft-side complement at reduced actuating forces, as the elastic elements are already in a pre-loaded state ready to push the locking element into engagement.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The locking mechanism is segmented into distinct functional components: a positive locking element for engagement, elastic force transmission means for pre-tensioning, and an electric drive with screw mechanism for actuation. This segmentation allows each component to be optimized independently, contributing to a more compact overall structure while reducing the force requirements for operation.

Inventive Principle:
Principle #1Segmentation

2Reliability

If high actuating forces are used for locking, then reliable engagement is achieved, but energy consumption increases

Engineering Contradiction:
Improvelocking engagement reliabilityVSAvoidactuator energy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The elastic force transmission means are pre-loaded to a defined prestoring force before the locking operation begins. This preliminary action stores mechanical energy in the elastic elements, which is then released during engagement to ensure reliable locking with minimal additional energy input from the electric actuator.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The elastic force transmission means serve themselves by automatically pushing the positive locking element toward the shaft-side complement as soon as the play is overcome. This self-service mechanism ensures reliable engagement without requiring continuous high-force actuation from the electric motor, thereby reducing energy consumption.

Inventive Principle:
Principle #25Self-service

3Volume of moving object

If the locking mechanism is integrated into the electric motor drive unit, then space is saved, but the actuator must be compact

Engineering Contradiction:
Improvelocking mechanism volumeVSAvoidactuator design
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The conventional mechanical actuation system is replaced with an electric drive that utilizes a screw mechanism. This substitution allows for a more compact actuator design with fewer mechanical linkages, enabling integration into the electric motor drive unit while maintaining the required locking functionality.

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

Solution Approach 2:

The locking mechanism components are nested within the electric motor drive unit structure. The positive locking element is arranged coaxially to the shaft and can be supported against the housing section, effectively nesting the locking mechanism within the existing motor housing space, thereby saving overall system volume.

Inventive Principle:
Principle #7Nested doll (Nesting)

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

Enables a compact, cost-effective, and energy-efficient locking mechanism that requires minimal actuating force, suitable for vehicles, including semi-autonomous and fully autonomous vehicles, with enhanced reliability in emergency scenarios.

Implementation Method 1

at least one elastic force transmission means, in particular in the form of at least one spring element

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

This energy storage device pre-tensions the positive locking element against its shaft-side complement until the shaft assumes a suitable orientation relative to the positive locking element for a positive lock

Methodology Applied
Scientific EffectSpring force: Spring

Implementation Method 3

The locking actuator has an electric drive with a stator which drives an internal rotor with permanent magnets

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 4

The locking actuator has an electric drive with a stator which drives an internal rotor with permanent magnets

Methodology Applied
Scientific EffectLorentz force: Lorentz Force

Implementation Method 5

the rotor being designed in the form of a threaded nut of a screw drive which, depending on its direction of rotation, can be moved in the longitudinal direction along a threaded spindle with which it interacts

Methodology Applied
Scientific EffectScrew mechanism: Screw

Data Source

PatentEP4441401B1Locking mechanism, electric motor drive unit, vehicle and method for locking a shaft of a drive train
Publication Date: 2026.01.28 SCHAEFFLER TECHNOLOGIES AG & CO KG
  • EP4441401B1 patent drawingFigure 1
  • EP4441401B1 patent drawingFigure 2
  • EP4441401B1 patent drawingFigure 3

AI summary

The invention relates to a locking mechanism (2), in particular of a vehicle, between a locking actuator (4) and a lockable shaft (6) of a drive train, in which a form-fit element (8) which can be actuated in an axial reciprocating movement (X-X) and longitudinally with respect to the shaft (6) can, when in a state of lying with its end face against a shaft-side complement (10) to which said form-fit element (8) can be form-fittingly connected in some sections, be prestressed longitudinally with respect to the shaft (6) by means of at least one elastic force-transmitting means (12) such that the form-fit element can engage in a defined manner with said shaft-side complement (10). In a locked state of the shaft (6), in which the form-fit element (8) and the shaft-side complement (10) engage one with another in a form-fit region (FB) of the locking mechanism (2), the form-fit element (8) is supported against a housing section (EM-G) of an electric motor drive unit (EM-AE), to which housing section the locking actuator (4) is attached. The locking mechanism (2) has a clearance (BS) between the form-fit element (8) and the shaft-side complement in the form-fit region (FB) and in the circumferential direction of the shaft (6).