EV Drivetrain One-Way Clutch Layout for Regenerative Shifting
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Solution Overview
Problem
Existing electric vehicle drivetrains with one-way clutches prevent power transmission from the rear wheel to the electric motor during deceleration, hindering regenerative control and making gear shifting difficult, and also prevent the vehicle from being pushed backward due to locked gears during reverse rotation.
Innovation Solution
A drivetrain with two power transmission paths, each with a one-way clutch, allows power transmission from the drive shaft to the driven shaft in one direction but not the reverse, and includes a shift clutch member to smoothly switch between paths during deceleration, enabling regenerative control and allowing the vehicle to be pushed backward by preventing reverse power transmission to the electric motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If one-way clutches are used in both power transmission paths to prevent reverse power transmission, then the electric motor is protected from reverse rotation, but regenerative control cannot be performed during deceleration
Solution Approach 1:
The patent makes the clutch members dynamic by allowing their engagement state to change based on operating conditions. The first clutch member can be disengaged during deceleration to enable regenerative control, while the second clutch member remains engaged to maintain one-way clutch functionality. This dynamic adjustment resolves the contradiction between motor protection and regenerative control capability.
2Ease of operation
If both power transmission paths have one-way clutches engaged, then power transmission in normal direction is controlled, but gear shifting becomes difficult requiring motor reversal
Solution Approach 1:
The patent employs dynamic clutch control where the first clutch member is disengaged during gear shifting operations. This allows the gears to be shifted without the constraint of engaged one-way clutches, eliminating the need for motor reversal. The clutch engagement state is dynamically adjusted based on whether the vehicle is accelerating or shifting gears, simplifying the gear shifting process.
3Power
If reverse rotation of rear wheel is transmitted through both power transmission paths, then the drivetrain provides torque during reverse pushing, but gears and shafts become locked preventing rear wheel rotation
Solution Approach 1:
The patent segments the power transmission paths by using separate clutch members for each path. The first clutch member can be disengaged independently to allow reverse rotation of the rear wheel without transmitting torque through the drivetrain. This segmentation prevents the locking of gears and shafts while still providing the option to transmit torque when needed, resolving the contradiction between power transmission and reverse pushing capability.
Data Source
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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.