Hybrid Transmission Engagement Control for Smooth Gear Shifts

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Solution Overview

Problem

Hybrid vehicles experience rough transitions when shifting gears due to driveline torque disturbances caused by engine idle speed changes during transmission shifts, particularly from park to drive or reverse, leading to inefficiencies and potential battery charging issues.

Innovation Solution

Adjusting the engine speed in response to the transmission's engaging state by a controller, allowing for smoother transitions by commanding lower engine speed and torque during gear engagement and adjusting timing to minimize torque disturbances during gear shifts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the engine idle speed is increased to compensate for torque converter turbine load during transmission engagement, then the engine can maintain speed, but driveline torque disturbances increase causing rough transitions

Engineering Contradiction:

Improveengine speedVSAvoiddriveline torque disturbance

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The controller preemptively adjusts the requested engine speed to a lower value before the transmission engagement is complete, anticipating the torque converter turbine load increase. This preliminary action prevents the engine speed controller from having to work against the developing load, thereby avoiding driveline torque disturbances while maintaining engine speed throughout the transition.

Inventive Principle:

Principle #10Preliminary action

2Speed

If the engine speed controller works against torque converter turbine load to maintain engine speed, then engine speed is maintained, but driveline torque disturbances occur

Engineering Contradiction:

Improveengine speedVSAvoidtorque disturbance

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The controller applies a preliminary anti-action by reducing the requested engine speed before the torque converter turbine load fully develops. This counteracts the impending load increase, preventing the engine speed controller from having to generate corrective torque that would cause driveline disturbances. The engine speed is maintained smoothly without the harmful feedback loop.

Inventive Principle:

Principle #9Preliminary anti-action

3Object-affected harmful factors

If engine speed commands are adjusted during transmission disengagement, then driveline torque disturbances are reduced, but control complexity increases

Engineering Contradiction:

Improvedriveline torque disturbanceVSAvoidcontrol system complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The controller dynamically adjusts the requested engine speed based on the real-time transmission engaging state. During engagement, the controller commands a lower engine speed that transitions smoothly as the transmission engages. During disengagement, the controller adjusts timing of speed commands. This dynamic adaptation reduces driveline torque disturbances while managing control complexity through systematic state-based control logic.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11820382B2System and method for smooth transmission engagement and disengagement

Publication Date: 2023.11.21 FORD GLOBAL TECH LLC

AI summary

Systems and methods for transitioning a hybrid vehicle from park or neutral to drive or reverse are presented. In one example, a requested engine speed is adjusted in response to a transmission disengaging indication and a transmission disengaging timer when a transmission is being disengaged from a gear. In another example, the requested engine speed is adjusted in response to a transmission engaging indication and a transmission engaging timer when the transmission is being engaged to a gear.