Vehicle Transmission Torque Continuity During Shifting
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Solution Overview
Problem
Automated manual transmissions with synchro-mesh type shifting mechanisms experience torque disconnection during automatic shifting, leading to decreased shifting ability and a backward pulling effect, requiring additional monitors that increase manufacturing cost and weight.
Innovation Solution
A transmission system with a first and second input shaft, countershafts, transfer gear pairs, one-way clutches, and shift gear pairs, allowing selective torque transmission and gear ratio adjustment using synchronizers to prevent torque disconnection and improve shifting ability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If power is disconnected from the engine during automatic shifting in a synchro-mesh type transmission, then gear shifting can be performed, but torque is decreased and shifting ability deteriorates causing backward pulling effect
Solution Approach 1:
The transmission system is divided into two independent input shafts (first input shaft and second input shaft) that can operate separately. The first input shaft maintains continuous power connection to the engine, while the second input shaft is disconnected during shifting. This segmentation allows one shaft to provide continuous torque while the other performs shifting operations, resolving the contradiction between maintaining torque and enabling gear changes.
Solution Approach 2:
A one-way clutch is introduced as an intermediary component between the first input shaft and the first countershaft. This one-way clutch allows torque to be transmitted from the first input shaft to the first countershaft during shifting operations without preventing the relative rotation needed for gear engagement. It mediates between the need for continuous power transmission and the need for torque disconnection during shifting.
2Ease of operation
If two monitors are added to reduce deterioration of shifting ability, then shifting performance improves, but manufacturing cost and weight increase
Solution Approach 1:
The transmission system uses passive mechanical components (one-way clutch, two input shafts, transfer gear pairs) that automatically perform the function of monitoring and controlling torque during shifting. The one-way clutch self-regulates torque transmission based on rotation direction, and the dual input shaft configuration inherently provides the monitoring function without requiring active electronic sensors or control systems. This eliminates the need for two separate monitors while maintaining shifting performance.
Data Source
AI summary
A transmission for a vehicle may include a first input shaft continuously receiving torque from a power source, a second input shaft selectively receiving torque from the power source through a clutch, a first countershaft and a second countershaft connected with the first input shaft and the second input shaft, respectively, by a transfer gear pair, coupling devices transmitting torque to the first countershaft and the second countershaft from the first input shaft and the second input shaft, respectively, by selecting the transfer gear pairs, a one-way clutch restricting torque provided to the first input shaft to be transmitted only to the first countershaft from the first input shaft, and a shifting mechanism configured to change and output power from the power source to the output shaft by selecting a shift gear pair corresponding to a speed of the vehicle, using a synchronizer.