Power Train Shift Shock Reduction via Torque Phase Control
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Solution Overview
Problem
Existing shift shock reduction apparatuses for power trains with automatic transmissions face issues of large downshift shocks due to unbalanced working oil pressure control during pre-torque down, leading to transmission output torque fluctuations and potential shift shocks.
Innovation Solution
A control system that differentiates working oil pressure control for the engagement side frictional element based on whether a pre-torque down is executed, with a steeper rising gradient during the torque phase when pre-torque down is performed, and maintaining the same gradient during the inertia phase, to prevent imbalance and reduce shift shocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If pre-torque down is executed during torque phase, then shift shock is reduced, but transmission output torque is largely pulled down causing large downshift shock
Solution Approach 1:
The control system executes preliminary torque down during the torque phase before the inertia phase begins. By reducing engine torque in advance while the frictional element is still engaged and transmission torque capacity is sufficient, the system prepares for the upcoming gear shift without causing shock. This preliminary action allows the frictional element to be fully engaged before torque reduction occurs, preventing the transmission output torque from being pulled down excessively.
Solution Approach 2:
The control system dynamically adjusts the torque down strategy based on the gear shift phase. During the torque phase, a first torque down control is executed with the frictional element engaged, while during the inertia phase, a second torque down control is executed. This dynamic adaptation ensures that torque reduction occurs at the appropriate timing and magnitude for each phase, preventing both shift shock and excessive transmission output torque reduction.
2Device complexity
If torque down control is executed only during inertia phase, then implementation is simple, but shift shock at initial stage cannot be avoided
Solution Approach 1:
The control system executes preliminary torque down during the torque phase before the inertia phase begins. By reducing engine torque in advance while the frictional element is still engaged and transmission torque capacity is sufficient, the system prepares for the upcoming gear shift without causing shock. This preliminary action allows the frictional element to be fully engaged before torque reduction occurs, preventing the transmission output torque from being pulled down excessively.
Solution Approach 2:
The control system dynamically adjusts the torque down strategy based on the gear shift phase. During the torque phase, a first torque down control is executed with the frictional element engaged, while during the inertia phase, a second torque down control is executed. This dynamic adaptation ensures that torque reduction occurs at the appropriate timing and magnitude for each phase, preventing both shift shock and excessive transmission output torque reduction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures reduced shift shocks by maintaining adequate transmission torque capacity during pre-torque down, preventing large downshift shocks and ensuring consistent torque control during gear shifts.
Implementation Method 1
an automatic transmission having a frictional element to be engaged at upshift
Data Source
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AI summary
A shift shock reducing apparatus for a power train having an engine (1) and an automatic transmission (2) having a frictional element that is to be engaged at upshift, comprising a control section that executes, during upshift, a torque down of the engine (1) that starts before the start of an inertia phase in which a gear ratio of the transmission (2) is changing from a before-shift gear ratio to an after-shift gear ratio, and a control section that makes larger a rising gradient of working oil pressure that is supplied to the frictional element to be engaged at upshift when the torque down of the engine (1) that starts before the start of the inertia phase is executed than that when the torque down is not executed.