Shift-by-wire Park Verification via Electric Machine Energy Absorption

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Solution Overview

Problem

Conventional shift-by-wire systems face challenges in verifying the functionality of secondary mechanical or hydraulic backup systems, particularly in maintaining the intended gear position during testing without causing noise or unintended gear shifts, especially when using stored mechanical energy.

Innovation Solution

An electro-mechanical system employing a torsion spring and electric machines to delatch and relatch the secondary mechanism, allowing the system to return noiselessly to the park position, with electric machines acting as generators to absorb energy and maintain the vehicle in Park during verification testing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a secondary mechanical backup system is used in shift-by-wire systems, then system reliability is improved, but verification of the backup system creates noise and may cause unintended gear shifts

Engineering Contradiction:

Improvesystem reliabilityVSAvoidnoise and unintended gear shifts

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The electric machine serves as an intermediary between the torsion spring and the gear shift mechanism. During verification testing, the electric machine engages in generator mode to absorb the energy released by the torsion spring, acting as a mediator that prevents the spring's energy release from causing noise or unintended gear shifts while still allowing the backup system to be tested

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The torsion spring's energy release, which normally would cause noise and potential unintended gear shifts during verification, is converted into a beneficial testing opportunity. By engaging the electric machine as a generator, the harmful energy release is transformed into useful electrical energy absorption, allowing verification of the backup system without the negative effects

Inventive Principle:

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

2Reliability

If the torsion spring capacity is increased to ensure independent return to park, then the backup system reliability is improved, but the energy release during delatching becomes more intense

Engineering Contradiction:

Improvebackup system reliabilityVSAvoidenergy release force

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The electric machine acts as an intermediary that manages the force interaction between the high-capacity torsion spring and the gear shift mechanism. During delatching, the electric machine engages as a generator to absorb the intense energy release, mediating the force transfer and preventing the high force from causing noise or unintended gear shifts

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces a purely mechanical energy absorption mechanism with an electromechanical system. Instead of using mechanical friction or damping to absorb the torsion spring's energy, the system uses the electric machine in generator mode to convert the mechanical energy into electrical energy, providing a more controlled and efficient means of managing the force

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If verification testing of the backup system is performed, then system functionality is confirmed, but the gear position may change unintentionally during the test

Engineering Contradiction:

Improvesystem functionality verificationVSAvoidgear position stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The electric machine serves as a mediator that maintains gear position stability during verification testing. By engaging as a generator during delatching, it controls the energy release and prevents the gear shift mechanism from moving unintentionally, ensuring the gear position remains stable throughout the test

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system uses feedback control to maintain gear position stability during verification. The electric machine monitors and responds to the energy release from the torsion spring, adjusting its generator engagement to absorb energy and prevent unintended gear position changes, ensuring stable verification testing

Inventive Principle:

Principle #23Feedback

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

Ensures reliable verification of the secondary failsafe mechanism without human intervention, maintaining the vehicle in the intended gear position and preventing unintended gear shifts, thus ensuring system integrity and user confidence.

Implementation Method 1

using the electric machine to absorb energy released by a spring when delatching

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

an electro-mechanical backup system which uses a torsion spring of sufficient capacity that can return the system back to a gearshift park state

Methodology Applied

Scientific EffectElastic potential energy: Spring

Data Source

PatentUS8671745B2Shift-by-wire default-to-park functional verification

Publication Date: 2014.03.18 FORD GLOBAL TECH LLC

AI summary

A method for testing a transmission gear shift device includes using an electric machine and a primary mechanism to place the device and a secondary mechanism, latched to the primary mechanism, in a park position, using a motor to delatch the secondary mechanism from the primary mechanism, using the electric machine to absorb energy released by a spring when delatching, and using the electric machine to relatch the secondary mechanism to the primary mechanism.