Shift-by-Wire Actuator with Capacitor Fail-Safe for Space-Constrained Transmissions

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Solution Overview

Problem

Conventional mechanical transmission gear shift assemblies occupy significant space in vehicles, making them less efficient in terms of compartment space utilization, especially with the introduction of new automotive features and technologies.

Innovation Solution

A shift-by-wire transmission range selector system with a dual redundant motor configuration and a fail-safe release motor, which allows the actuator to operate at low voltage and high temperature without gear reduction, and safely returns the transmission to the PARK position in case of system failure using energy stored in a capacitor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mechanical linkage system is used for transmission gear shift, then the gear position can be reliably changed, but significant compartment space is occupied

Engineering Contradiction:

Improvegear position controlVSAvoidcompartment space

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent replaces the mechanical linkage system with an electro-mechanical actuator that uses electrical signals and a motor-driven mechanism to control transmission gear positions. This substitution eliminates the need for extensive mechanical linkages while maintaining reliable gear position control through electronic actuation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and removes the mechanical linkage components from the transmission control system, retaining only the essential actuation function through a compact electro-mechanical actuator. This extraction eliminates unnecessary mechanical parts that occupied significant compartment space.

Inventive Principle:

Principle #2Taking out (Extraction)

2Volume of moving object

If a shift-by-wire system with electro-mechanical actuator is used, then compartment space is saved, but system reliability may be compromised during power failures

Engineering Contradiction:

Improvecompartment spaceVSAvoidsystem operation during failure

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent incorporates a spring-loaded mechanism that is pre-loaded and ready to automatically return the transmission to park position upon power failure. This preliminary action ensures that the fail-safe mechanism is already prepared and requires no external power or control signals to function when needed.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the potential harm of power failure into a beneficial automatic safety feature. The loss of power triggers the spring-loaded mechanism to automatically return the transmission to park, transforming a harmful condition into a protective action that ensures vehicle safety.

Inventive Principle:

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

3Reliability

If redundant motors are added to ensure operation under extreme conditions, then reliability improves, but device complexity increases

Engineering Contradiction:

Improveoperation at low voltage and high temperatureVSAvoidactuator configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent modifies the operating parameters of the electro-mechanical actuator to tolerate extreme conditions such as low voltage and high temperature. This is achieved through selective motor design and control strategy adjustments rather than adding redundant components, thereby maintaining system simplicity while improving reliability under extreme conditions.

Inventive Principle:

Principle #35Parameter changes

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

The solution effectively saves space by eliminating the need for mechanical linkages, ensures reliable gear position shifting, and provides a safe return to PARK position during system failures, enhancing operational reliability and efficiency.

Implementation Method 1

In the event of a power or system failure, a fail safe release motor is actuated by energy stored in a capacitor

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

The actuator may include at least one electric motor configured to drive an output shaft through a gear train for shifting a gear position

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS9239108B2Shift-by-wire transmission range selector system and actuator for the same

Publication Date: 2016.01.19 STONERIDGE CONTROL DEVICES INC

AI summary

In general, a shift-by-wire transmission range selector system consistent with the present disclosure may include an actuator one or more electric motors to allow the actuator to operate for shifting the gear position of a transmission. In the event of a power or system failure, a fail safe release motor may be actuated by energy stored in a capacitor. The fail safe release motor drives a slide cam to release a trigger arm. Upon release of the trigger arm, a spring-driven mechanism safely returns the transmission to the PARK position by rotating an output shaft. A redundant control link may be provided, configured to actuate the fail safe release motor in the event of a power or system failure.