Transmission Hydraulic Pressure Estimation Across Shift Phases
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Solution Overview
Problem
The existing hydraulic pressure calculation methods in automatic transmissions fail to accurately account for varying delays in response during the switching of friction engagement elements, leading to inaccuracies in estimated hydraulic pressure calculations.
Innovation Solution
A hydraulic pressure calculation apparatus that uses mapping data specific to different phases of engagement, including connection and disconnection states, to reflect the relationship between instructive and actual hydraulic pressures, incorporating variables such as accelerator operation amount, oil temperature, and input shaft rotation speed to provide accurate output variables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single time constant is used to calculate estimated hydraulic pressure, then the calculation process is simple, but the accuracy deteriorates because the delay in response is not always constant during switching
Solution Approach 1:
The switching period is divided into multiple phases (first phase, second phase, third phase) with different mapping data for each phase. This segmentation allows the system to capture the varying delay characteristics at different stages of switching, improving accuracy without requiring a single complex model
Solution Approach 2:
The mapping data is made dynamic by selecting different mappings based on the current phase of switching. The system transitions from static single-time-constant models to dynamic phase-dependent models, allowing the calculation to adapt to changing system conditions during the switching process
2Measurement precision
If phase-specific mapping data is used to improve accuracy, then the estimated hydraulic pressure becomes more accurate, but the data structure and processing complexity increase
Solution Approach 1:
Mapping data for multiple phases is pre-calculated and stored in memory before actual switching occurs. This preliminary preparation eliminates the need for complex real-time calculations, reducing processing complexity while maintaining high accuracy during actual operation
Data Source
AI summary
A hydraulic pressure calculation apparatus is applied to a gear shifting system including a transmission configured to switch between a connected state and a disconnected state of a friction engagement element depending on a hydraulic pressure supplied from a hydraulic circuit, and a hydraulic controller configured to control the hydraulic circuit. The hydraulic pressure calculation apparatus includes a memory and a processor. The memory stores pieces of mapping data of a plurality of phases obtained by dividing a period from a start to an end of switching between the connected state and the disconnected state of the friction engagement element. Each piece of the mapping data defines a mapping. The processor is configured to output, as an output variable, an estimated hydraulic pressure variable indicating an estimated value of an actual hydraulic pressure supplied from the hydraulic circuit to the friction engagement element.