Planetary Transmission Synchronizer for Compact Gear Shifting

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Solution Overview

Problem

Modern vehicles face challenges in accommodating transmissions within limited space, necessitating a compact design that enables mechanical synchronization.

Innovation Solution

A transmission design featuring an input shaft, output shaft, and a planetary gearset with a coupling disc, axially movable coupling sleeve, and synchronizer ring, allowing for high and low gear modes with reduced axial extension, utilizing a synchronizer ring to transfer axial motion and synchronize rotational speeds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If a compact transmission design is implemented to reduce axial extension, then the transmission fits better in modern vehicles with limited space, but mechanical synchronization becomes more difficult to achieve

Engineering Contradiction:
Improveaxial extensionVSAvoidmechanical synchronization mechanism
Core Design Contradiction:
Length of moving objectVSDevice complexity

Solution Approach 1:

The patent combines the synchronizer ring and coupling sleeve into a single integrated component that performs both synchronization and coupling functions. The synchronizer ring is axially movable relative to the planetary gearset and can engage with the coupling sleeve, allowing both synchronization and power transmission coupling to occur within the same axial space, thereby reducing overall axial extension while maintaining mechanical synchronization capability

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The synchronizer ring is positioned within the axial space of the planetary gearset, and the coupling sleeve is nested within the synchronizer ring's engagement path. This nested arrangement allows the synchronization mechanism to be contained within the existing axial envelope of the planetary gearset rather than adding separate external synchronization components, thus reducing the overall axial extension of the transmission

Inventive Principle:
Principle #7Nested doll (Nesting)

2Adaptability or versatility

If the coupling sleeve is made axially movable to enable gear shifting, then gear mode changes become possible, but drag losses increase during motion

Engineering Contradiction:
Improvegear mode switchingVSAvoiddrag losses
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The synchronizer ring is designed to synchronize the rotational speeds of the planetary gearset and coupling sleeve before the coupling sleeve engages with the coupling disc. This preliminary synchronization action ensures that when the coupling sleeve moves into the engaged position, the rotational speeds are already matched, minimizing relative motion and drag losses during the engagement process while still enabling gear mode changes

Inventive Principle:
Principle #10Preliminary action

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

The design provides a compact transmission that supports efficient gear shifting with reduced drag losses and minimal axial extension, suitable for vehicles with limited space.

Implementation Method 1

The synchronizer ring is configured to transfer an axial motion of the ring gear in a first direction towards the coupling sleeve and the coupling disc

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4246013B1Transmission powertrain vehicle and method
Publication Date: 2025.07.23 SCANIA CV AB
  • EP4246013B1 patent drawingFigure 1~2
  • EP4246013B1 patent drawingFigure 3a~3b
  • EP4246013B1 patent drawingFigure 4a~4b

AI summary

The disclosure concerns a transmission (6) comprising an input shaft, an output shaft, and a planetary gearset. The planetary gearset comprises a sun gear connected to the input shaft, a ring gear (40) that is axially movable, and at least one planet gear rotatably supported on a planet gear carrier (44) that is connected to the output shaft. The transmission (6) comprises a coupling disc (46) connected to the input shaft, an axially moveable coupling sleeve (48), and a synchronizer ring (50) arranged between the coupling sleeve (48) and the ring gear (40). The synchronizer ring (50) is configured to transfer an axial motion of the ring gear (40) in a first direction (52) towards the coupling sleeve (48) and the coupling disc (46). The coupling sleeve (48) is moveable into an engaged position with the coupling disc 46 at least in part by the synchronizer ring (50).