Target Volume Torque Phase Control for Automatic Transmission Upshifts
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Solution Overview
Problem
Automatic transmission systems face instability and shudder issues during upshifts due to mismatched capacity between releasing and applying elements, leading to turbine speed fluctuations and power disruptions, which conventional feedback control struggles to address effectively.
Innovation Solution
The implementation of target volume torque phase control, using a model-based approach to compute and update target volumes for accumulators, and generating continuously variable duty cycles for solenoids to manage fluid flow rates, ensuring smooth transitions and stable upshift operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional feedback control is used for upshift operations, then system simplicity is maintained, but shift quality deteriorates due to instability and turbine speed fluctuations
Solution Approach 1:
The control system performs preliminary actions by pre-calculating target accumulator volumes and generating continuously variable duty cycles before the upshift operation begins. The model-based approach anticipates the fluid flow requirements and prepares control parameters in advance, allowing the system to execute smooth upshifts without reacting to turbulence after they occur.
Solution Approach 2:
The invention implements dynamic control by continuously adjusting the duty cycle of solenoids based on real-time fluid flow rates and accumulator volumes. The control system adapts the flow rate dynamically during the upshift process, transitioning from fixed duty cycles to continuously variable duty cycles that respond to changing system conditions, thereby maintaining stability throughout the transient operation.
2Measurement precision
If fixed duty cycles are used for solenoids, then control simplicity is maintained, but fluid flow rate control precision deteriorates
Solution Approach 1:
The system transitions from static fixed duty cycles to dynamic continuously variable duty cycles that adjust in real-time based on fluid flow rate measurements and model predictions. This dynamic adaptation allows precise control of the fluid flow rate through the accumulators during the upshift operation, matching the actual system behavior more accurately than fixed cycles could achieve.
Solution Approach 2:
The control system incorporates feedback mechanisms by monitoring actual fluid flow rates and comparing them against target values derived from the model. The duty cycles are continuously adjusted based on this feedback, creating a closed-loop control system that achieves high precision in fluid flow rate control while compensating for variations in system conditions.
3Stability of the object's composition
If accumulators are used to reduce torque variation sensitivity, then torque phase stability is improved, but pressure response predictability deteriorates
Solution Approach 1:
The model-based control approach performs preliminary calculations of target accumulator volumes and expected pressure responses before the upshift operation. By anticipating the pressure build-up and fluid flow requirements, the system can predict and compensate for the delayed pressure response characteristic of accumulators, maintaining stability while improving predictability.
Solution Approach 2:
The control system introduces an intermediate computational model that acts as a mediator between the solenoid duty cycle commands and the actual accumulator pressure responses. This model-based intermediary layer predicts the delayed pressure responses and adjusts control signals accordingly, bridging the gap between control inputs and actual system responses.
4Adaptability or versatility
If calculated accumulator volume is used for control, then control adaptability is improved, but measurement consistency deteriorates due to spring compression variations
Solution Approach 1:
The system uses feedback from actual fluid flow rate measurements and pressure sensors to continuously update and correct the calculated accumulator volume. This feedback mechanism compensates for variations in spring compression and other non-ideal behaviors, maintaining measurement consistency while preserving the adaptability of model-based control.
Solution Approach 2:
The control system dynamically adjusts control parameters including duty cycles and target volumes based on changing operating conditions such as fluid temperature, pressure, and flow rate. By continuously adapting these parameters, the system maintains accurate volume measurements and control precision across varying operational states despite spring compression variations.
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 solution stabilizes upshift operations, prevents bump-along and turbine speed flare, and ensures smooth torque handover between elements, improving shift quality and predictability by precisely controlling the duty cycles of solenoids based on real-time torque and speed dynamics.
Implementation Method 1
An electromagnetic actuator receives a control signal and selectively interrupts flow of the fluid to the first gear engagement element based on a duty cycle of the control signal
Implementation Method 2
clutches in automatic transmissions are typically actuated by pressure from fluid such as oil. Oil fills a cavity including a piston and displaces the piston to engage the clutch
Implementation Method 3
The accumulator 10 includes a spring 12 that is compressed when a piston 14 in the accumulator 10 is displaced by pressure from the oil
Data Source
AI summary
A transmission control system includes a first gear engagement element that receives fluid and engages a first gear. An electromagnetic actuator selectively interrupts fluid flow to the first gear engagement element based on a duty cycle of a control signal. A control module adjusts the duty cycle so that a fluid flow rate continuously decreases as the first gear engagement element produces a first torque sufficient to hold the first gear. The flow rate is based on a first estimated volume of the fluid necessary for the first gear engagement element to produce the first torque. The control module computes a current volume of the fluid when the first gear engagement element produces the first torque. The control module adjusts a value of the first estimated volume for subsequent transmission control when a difference between the current volume and the first estimated volume is greater than a predetermined volume.