Negative Torque Upshift Control Using Actual Clutch Torque Feedback

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Solution Overview

Problem

Conventional negative torque upshift control methods in automatic transmissions are inefficient due to the use of engine torque as a proxy for clutch torque, leading to inconsistent shift quality and lack of optimal clutch synchronization during negative torque conditions.

Innovation Solution

A controller-based methodology that calculates actual offgoing clutch torque and pressure through multiple stages, including slip, inertia, near-sync boost, post-sync, and exhaust phases, while optimizing oncoming clutch control via fill, slow ramp, and quick-lock stages, to improve shift feel and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If engine torque is used as a proxy for clutch torque in conventional negative torque upshift control, then control implementation is simplified, but shift quality becomes inconsistent and intensive calibrations are required

Engineering Contradiction:

Improvecontrol implementation complexityVSAvoidshift quality consistency

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent implements a feedback mechanism by calculating actual clutch torque based on measured turbine speed and its derivative, then using this actual torque to determine clutch pressure commands. This closed-loop approach replaces the open-loop proxy method, ensuring accurate torque control and consistent shift quality without requiring intensive calibrations.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces the mechanical/proxy-based torque estimation (using engine torque as a substitute) with a dynamic calculation based on turbine speed measurement and differentiation. This substitution provides direct torque information derived from actual system behavior, eliminating the inaccuracies of the proxy approach.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If the oncoming clutch is used as the main control element during negative torque upshift, then the clutch can respond to torque changes, but turbine speed decreases more rapidly than desired leading to suboptimal shifts

Engineering Contradiction:

Improveclutch response to torque changesVSAvoidturbine speed control accuracy

Core Design Contradiction:

Adaptability or versatilityVSSpeed

Solution Approach 1:

The patent inverts the conventional control approach by making the offgoing clutch (rather than the oncoming clutch) the main control element during negative torque upshift. By controlling clutch release instead of clutch application, the system achieves better turbine speed control and prevents excessive speed drops, while still maintaining adaptability through proper synchronization of the oncoming clutch.

Inventive Principle:

Principle #13The other way round (Inversion)

3Measurement precision

If intensive calibrations and feed-forward controls are used to force offgoing clutch to particular torque levels, then torque control can be achieved, but control complexity increases significantly

Engineering Contradiction:

Improveclutch torque control precisionVSAvoidcontrol calibration complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent enables the control system to determine its own operating parameters in real-time by calculating actual clutch torque from measured turbine speed. This self-determining approach eliminates the need for pre-programmed calibration tables and feed-forward controls, as the system adapts to current conditions dynamically without requiring extensive external calibration data.

Inventive Principle:

Principle #25Self-service

4Device complexity

If conventional negative torque upshift control is used without proper clutch synchronization, then control implementation is simpler, but shift quality and feel become inconsistent

Engineering Contradiction:

Improvecontrol synchronization complexityVSAvoidshift quality consistency

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent implements preliminary action by calculating and preparing offgoing clutch pressure commands before the actual shift event, based on predicted torque conditions. The control system proactively manages the offgoing clutch release trajectory and coordinates timing with oncoming clutch application, ensuring smooth synchronization and consistent shift quality without adding excessive complexity.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9188222B2Negative torque upshift control

Publication Date: 2015.11.17 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A vehicle includes a prime mover, input clutch, transmission, and controller. The transmission, which is selectively connected to the output shaft via the input clutch, has multiple friction clutches, including respective offgoing and oncoming clutches for a negative torque upshift. The controller includes a torque request module, offgoing clutch module, and oncoming clutch module. The torque request module limits input torque into the transmission during the negative torque upshift. The offgoing control module determines actual offgoing clutch torque capacity of the offgoing clutch, calculates an actual offgoing clutch pressure using the actual offgoing clutch torque capacity, and controls the offgoing clutch through the shift using the actual offgoing clutch pressure. The oncoming control module controls the oncoming clutch through multiple stages of control of the oncoming clutch, including a fill, staging, ramp, and quick-lock stage. Closed-loop pressure correction is provided via PID logic through the inertia and torque shift phases.