Two-Stage EV Transmission with One-Way Clutch Phase Matching
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Solution Overview
Problem
Existing two-stage transmissions in electric vehicles experience transmission shock and torque drop during shifting between speed modes, leading to inefficient energy transfer and discomfort for the driver.
Innovation Solution
The implementation of a ratchet-type one-way clutch in conjunction with a dog clutch and friction clutch system, which ensures simultaneous engagement of both clutches during shifting, thereby preventing torque drop and reducing transmission shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a two-stage transmission with dog clutch and friction clutch is used to expand the high efficiency driving range of the electric motor, then the energy efficiency is improved, but transmission shock and torque drop occur during shifting between speed modes
Solution Approach 1:
The one-way clutch is pre-configured in the planetary gear mechanism to automatically engage and maintain torque transmission path during shifting operations. This preliminary arrangement ensures that when transitioning between dog clutch and friction clutch, the one-way clutch provides continuous torque transfer, preventing torque drop and reducing transmission shock before the harmful effect can manifest.
Solution Approach 2:
The one-way clutch acts as an intermediary element between the input and output of the planetary gear mechanism. During shifting between speed modes, it serves as a mediator that maintains the torque transmission path, allowing smooth transition between the dog clutch and friction clutch engagement states without causing torque drop or transmission shock.
2Use of energy by moving object
If a two-stage transmission with dog clutch and friction clutch is used to expand the high efficiency driving range of the electric motor, then the energy efficiency is improved, but torque drop occurs during shifting between speed modes
Solution Approach 1:
The one-way clutch is pre-configured in the planetary gear mechanism to automatically engage and maintain torque transmission path during shifting operations. This preliminary arrangement ensures that when transitioning between dog clutch and friction clutch, the one-way clutch provides continuous torque transfer, preventing torque drop before it can occur.
Solution Approach 2:
The one-way clutch acts as an intermediary element that maintains the torque transmission path during shifting. It ensures continuous power flow from the input to the output through the planetary gear mechanism, preventing torque drop when transitioning between the dog clutch and friction clutch engagement states.
Data Source
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AI summary
The present invention relates to a two-stage transmission for an electrically driven vehicle including a dog clutch and a friction clutch, and an object of the present invention is to prevent a torque drop when shifting gears. The two-stage transmission for the electrically driven vehicle includes a planetary gear mechanism (12), a dog clutch (28), a friction clutch (30), an armature (26) to switch between the dog clutch (28) and the friction clutch (30), and an electromagnetic coil (31) to drive the armature (26). In the dog clutch (28) and the friction clutch (30), the coupling relationship among the rotational elements of the planetary gear mechanism (12) is set such that the dog clutch (28) is fastened and the friction clutch (30) is not fastened in speed reduction (the first speed), and the dog clutch (28) is not fastened and the friction clutch (30) is fastened in speed increase (the second speed) . To prevent the torque drop when shifting the gears, a ratchet-type one-way clutch (50) is disposed such that a rotational phase position of the ratchet-type one-way clutch (50) is coincident with that of the dog clutch (28). When shifting from the second speed to the first speed, since the rotational phase of the dog clutch (28) is adjusted by the ratchet-type one-way clutch (50), the shifting is instantaneously completed without waiting operation for the phase adjustment, resulting in preventing a transmission shock.