Automatic Transmission Shift Control for Engine Speed Limiting
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Solution Overview
Problem
Existing automatic transmission shift control technologies fail to appropriately limit engine rotational speed, leading to sudden upshifting and an unusual vehicle performance feel, as they do not account for varying engine rotational speed limits due to engine protection or failsafe controls.
Innovation Solution
An automatic transmission control apparatus with an engine rotational speed limit verifying section and a shift control characteristic changing section, which adjusts the shift schedule based on the engine rotational speed limit, promoting a stronger tendency to select higher gear stages when the rotational speed is limited, thereby preventing frequent upshifting and maintaining appropriate engine speed limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shift characteristic curve is changed to a lower vehicle speed to limit engine rotational speed, then the engine rotational speed can be limited to a lower value, but frequent sudden upshifting occurs causing unusual vehicle performance
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the shift characteristic curve based on the magnitude of engine rotational speed limitation. When the engine rotational speed limit is lowered, the system calculates an appropriate shift characteristic curve that corresponds to the degree of limitation, rather than using a fixed lower vehicle speed curve. This allows the shift timing to be proportionally adjusted, preventing sudden upshifting while still achieving the desired engine speed limitation.
2Reliability
If the shift characteristic curve is set for the smallest engine rotational speed limit, then the engine rotational speed can be limited effectively, but the system cannot adapt when the rotational speed limit is only slightly reduced
Solution Approach 1:
The patent implements dynamics by making the shift characteristic curve adaptive rather than static. The system continuously monitors the engine rotational speed limit magnitude and dynamically selects or calculates the appropriate shift characteristic curve accordingly. This allows the transmission control to adapt to different limitation scenarios - whether the limit is slightly reduced or severely constrained - optimizing both engine speed control and shift behavior for each specific condition.
Solution Approach 2:
The system changes the parameter of the shift characteristic curve based on the engine rotational speed limit magnitude. Instead of using a single curve for all limitation scenarios, the patent calculates or selects curves that correspond to the actual degree of speed limitation, enabling appropriate adaptation to different operational conditions while maintaining reliable engine speed control.
3Device complexity
If the same shift characteristic curves are used regardless of the magnitude of engine rotational speed limit, then the system is simple to implement, but frequent upshifting occurs when the limit is only slightly reduced
Solution Approach 1:
The patent introduces parameter changes to the shift characteristic curve selection based on the engine rotational speed limit magnitude. The system calculates the appropriate curve according to the actual limitation degree, which improves engine speed control accuracy. While this increases complexity compared to using fixed curves, the patent implements this through systematic calculation methods that balance the improved control with manageable system complexity.
Data Source
AI summary
An automatic transmission control apparatus includes an engine rotational speed limit verifying section and a shift control characteristic changing section. The engine rotational speed limit verifying section is configured to receive an engine rotational speed limit value for limiting an engine rotational speed and determine if the engine rotational speed limit value is lower than a prescribed normal upper limit value. The shift control characteristic changing section is configured to change a shift schedule of an automatic transmission based on the engine rotational speed being limited by the engine rotational speed limit value and the automatic transmission having a stronger tendency to select a higher gear stage than if the engine rotational speed limit value was not being limited to a lower value than the prescribed normal limit value, when the engine rotational speed limit value is determined to lower than the prescribed normal upper limit value.