Stepped Spline Grounding Plate for Multi-Speed Electric Powertrain

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Solution Overview

Problem

Existing electric powertrains with single-speed transmissions face tradeoffs between off-line acceleration and top speed due to fixed gear ratios, and multi-speed transmissions experience binding issues from over-constraint of shifting components, such as sleeve jamming caused by tilt and positional tolerance stack-up.

Innovation Solution

A multi-speed electric powertrain system with a grounding plate featuring an inner stepped splined interface that allows vertical and horizontal movement of the clutch sleeve, reducing binding by dispersing torque reaction loads over greater contact areas and incorporating curved profiles to minimize edge loading.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multi-speed transmissions use mechanically grounded epicyclic gears to adjust gear ratio, then gear ratio adjustability is improved, but shifting components experience binding due to over-constraint

Engineering Contradiction:

Improvegear ratio adjustabilityVSAvoidshifting component binding

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The grounding plate is segmented into multiple independent grounding points (first, second, and third grounding points) that can independently contact the clutch sleeve. This segmentation allows the clutch sleeve to maintain rotational grounding while permitting axial movement, thereby preventing binding during gear shifts while maintaining gear ratio adjustability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The grounding plate transitions from a static, fully constrained design to a dynamic design where the grounding points can adaptively contact the clutch sleeve. The clutch sleeve is allowed axial movement while maintaining rotational grounding, creating a dynamic balance between constraint and freedom that prevents binding during shifting operations.

Inventive Principle:

Principle #15Dynamics

2Manufacturing precision

If clutch sleeve is mechanically constrained to prevent tilt and positional deviation, then positioning precision is improved, but axial translation ability deteriorates due to binding

Engineering Contradiction:

Improveclutch sleeve positioningVSAvoidaxial translation ability

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The grounding plate uses multiple segmented grounding points instead of a single rigid constraint. This allows the clutch sleeve to maintain precise radial positioning while permitting necessary axial translation, as each grounding point can independently accommodate movement without causing binding.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The design changes the constraint parameters by allowing axial movement while maintaining radial positioning. The grounding points are positioned and dimensioned to provide radial constraint precision while permitting axial translation, effectively changing which degrees of freedom are constrained and which are free.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If single-speed transmission is used, then device complexity is reduced, but tradeoffs between off-line acceleration and top speed increase

Engineering Contradiction:

Improvetransmission structureVSAvoidspeed/torque range

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The grounding plate design enables a single transmission system to perform multiple functions by allowing the clutch sleeve to both rotate (for gear ratio changes) and translate axially (for smooth shifting). This multi-functionality allows the transmission to achieve variable gear ratios without significantly increasing overall system complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The dynamic grounding plate design allows the transmission system to adapt between different operating modes (different gear ratios) while maintaining structural simplicity. The ability of the clutch sleeve to move axially and rotate provides the versatility needed for multi-speed operation without requiring complex additional mechanisms.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11441612B1Multi-speed electric powertrain with stepped splines that allow additional degrees of freedom

Publication Date: 2022.09.13 DANA HEAVY VEHICLE SYSTEMS GROUP LLC

AI summary

Various methods and systems are provided for a multi-speed electric axle assembly. The multi-speed electric axle assembly includes a grounding plate with an outer interface coupled to a housing interface and an inner stepped splined interface designed to selectively mate with a clutch sleeve. In the assembly, the inner stepped splined interface includes a plurality of steps that each include a first side that perpendicularly intersects a second side and the first side of each step in the inner stepped splined interface includes a clearance between the first side and a stepped surface of the clutch sleeve.