EV Drivetrain Dual One-Way Clutch Shifting for Regenerative Braking

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Solution Overview

Problem

Existing electric vehicle drivetrains with one-way clutches in power transmission paths prevent regenerative control during deceleration and make gear shifting difficult, and do not allow the vehicle to be pushed backward due to locking of gears and shafts during reverse rotation.

Innovation Solution

A drivetrain design with two power transmission paths, each containing meshing gears and a one-way clutch, allowing power transmission in one direction while preventing it in the reverse direction, and a shift clutch member to switch between paths, enabling regenerative control and backward pushing by preventing the first path from transmitting reverse rotation to the electric motor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If one-way clutches are installed in both power transmission paths to enable bidirectional power transmission, then power can be transmitted in both directions during deceleration, but regenerative control cannot be performed because both clutches prevent power transmission from the driven shaft to the drive shaft

Engineering Contradiction:

Improvebidirectional power transmission capabilityVSAvoidregenerative control functionality

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The power transmission system is divided into two separate paths, each with its own one-way clutch. The first path includes a first one-way clutch that allows power transmission from drive shaft to driven shaft but blocks reverse transmission. The second path includes a second one-way clutch that allows power transmission from driven shaft to drive shaft but blocks reverse transmission. This segmentation enables selective activation of different paths based on operational requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A shift mechanism dynamically switches between the first and second power transmission paths based on the rotational direction of the drive shaft. During normal operation, the first path is active. During deceleration when regenerative control is needed, the shift mechanism engages the second path, allowing the second one-way clutch to transmit power from the driven shaft back to the drive shaft for electricity generation.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If the electric motor is reversed during gear shifting to change transmission paths, then different gear ratios can be achieved, but gear shifting becomes difficult and non-smooth

Engineering Contradiction:

Improvegear ratio switching capabilityVSAvoidgear shifting smoothness

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The transmission system is divided into two independent power transmission paths with different gear ratios. Each path has its own set of meshing gears and one-way clutch. The shift mechanism selectively engages either the first path or the second path without requiring motor reversal, enabling smooth gear ratio changes through mechanical path switching alone.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A shift mechanism acts as an intermediary device that switches between the first and second power transmission paths. This mediator component enables gear ratio changes by mechanically engaging or disengaging different paths, eliminating the need for electric motor reversal and achieving smooth gear shifting.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If both power transmission paths transmit reverse rotation from the rear wheel to the electric motor when the vehicle is pushed backward, then the drivetrain can handle reverse motion, but gears and shafts become locked and the rear wheel cannot rotate

Engineering Contradiction:

Improvereverse motion handling capabilityVSAvoidbackward pushing capability

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The power transmission system is segmented into two paths with opposite one-way clutch configurations. The first one-way clutch allows forward power transmission but blocks reverse transmission. The second one-way clutch allows reverse power transmission but blocks forward transmission. This segmentation ensures that during backward pushing, only the appropriate path is active while the other remains blocked, preventing gear and shaft locking.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The one-way clutches, which initially seem to restrict motion, actually enable backward pushing by selectively blocking reverse power transmission in the first path. When the vehicle is pushed backward, the first one-way clutch prevents power transmission from the driven shaft to the drive shaft, allowing the rear wheel to rotate freely without locking the gears and shafts.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS11226025B2Electric vehicle and drivetrain thereof

Publication Date: 2022.01.18 YAMAHA MOTOR CO LTD

AI summary

A drivetrain has a first speed path and a third speed path. The first speed path includes a one-way clutch that allows power transmission from the drive shaft toward the driven shaft but prevents power transmission in the opposite direction. The third speed path includes a one-way clutch that allows power transmission from the driven shaft toward the drive shaft but prevents power transmission in the opposite direction. The third speed path further includes a shift clutch member. This can provide a drivetrain capable of performing regenerative control to derive electricity appropriately from an electric motor and also capable of shifting gears smoothly.