Sliding Gear Declutching via Reactive Torque Cancellation

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Solution Overview

Problem

In hybrid power trains without integrated mechanical synchronization systems or input clutches, the existing methods for declutching a sliding gear are inefficient due to inaccuracies in estimating the torque of the combustion engine, leading to incomplete torque cancellation and premature or failed declutching attempts, which affect driving comfort and gear shift time.

Innovation Solution

A method that involves applying a zero torque request to all power sources, estimating the resistance torque on the sliding gear, calculating residual torque, and applying opposing cancellation torques to ensure complete declutching, without requiring additional components or resizing existing actuation motors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If torque cancellation is attempted using only combustion engine torque estimation, then declutching control is simplified, but declutching reliability deteriorates due to inaccurate torque estimation

Engineering Contradiction:

Improvedeclutching reliabilityVSAvoidtorque estimation accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent introduces an intermediary mechanism (torque sensor or reactive force measurement) to indirectly measure the combustion engine torque. Instead of relying solely on direct torque estimation from the combustion engine controller, the system uses the reactive force on the dogs as an intermediary indicator to infer the actual torque being transmitted, thereby improving measurement accuracy without requiring direct access to combustion engine torque data.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements a feedback loop where the reactive force on the dogs is continuously measured and used to adjust the torque cancellation strategy. The measured reactive force provides real-time feedback about the actual torque transmission state, allowing the control system to dynamically adjust electric motor torque application to achieve complete torque cancellation and reliable declutching.

Inventive Principle:

Principle #23Feedback

2Force

If powerful disengagement actuator is used to overcome friction force, then declutching force capability is improved, but device complexity increases

Engineering Contradiction:

Improvedisengagement force capabilityVSAvoidactuator system complexity

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

The patent replaces the traditional mechanical approach of using a powerful disengagement actuator to overcome friction forces with an electrical/toroidal approach. Instead of mechanically forcing the dogs apart with high force, the system uses electric motors to apply controlled torque that cancels the combustion engine torque, thereby eliminating the need for high-force mechanical actuators and reducing overall system complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent converts the harmful friction force that resists declutching into a beneficial measurement signal. The friction force creates a reactive force on the dogs that is measured and used as feedback to determine when complete torque cancellation has been achieved. Thus, the previously harmful friction becomes a useful indicator for controlling the declutching process.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If torque cancellation time is extended to overcome combustion engine response delay, then torque cancellation completeness is improved, but gear shift time increases

Engineering Contradiction:

Improvetorque cancellation completenessVSAvoidgear shift time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-positioning the sliding gear in a declutching-ready state and pre-coordinating the electric motor torque application with the combustion engine torque estimation. The electric motors are prepared to immediately apply counter-torque when declutching is commanded, reducing the overall time required for complete torque cancellation despite the combustion engine's slow response characteristics.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs periodic action through iterative torque cancellation attempts. Instead of relying on a single prolonged torque application, the system uses periodic measurements of reactive force and iterative adjustments of electric motor torque, canceling torque in controlled increments until complete declutching is achieved, thereby reducing total gear shift time while ensuring completeness.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS11167633B2Method of controlling the declutching of a sliding gear

Publication Date: 2021.11.09 NISSAN MOTOR CO LTD

AI summary

A control method is provided for controlling a declutching of a sliding gear of a vehicle gearbox having dogs. The sliding gear rotates with a shaft of the vehicle gearbox on which the sliding gear moves axially between a declutched position and an engaged position to transmit rotation to a vehicle wheel. The control method comprises applying a zero torque request to all power sources of the vehicle, applying a declutching instruction to the sliding gear, estimating a resistance torque on the dogs in absence of rapid declutching, calculating a residual torque on the dogs as a function of a calculated resistance torque and an anti-disengagement angle of the resistance torque on the dogs, cancelling the residual torque by application of two opposing cancellation torques on the sliding gear, and declutching the sliding gear.