Marine Drive Shift Control Using Throttle Sensor for Gear Changes

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Solution Overview

Problem

Marine propulsion systems are rendered inoperable or severely limited when the shift demand sensor fails, as they cannot receive operator input to control gear position, leading to the operator being locked in a specific gear with no ability to shift, even after restarting the engine.

Innovation Solution

The system employs the throttle demand sensor to provide a modified shift control by assigning predetermined throttle demand lever positions as shift command positions, allowing the generation of shift commands to change gear positions when the control lever reaches a specific shift command position, enabling limited shifting control and operation in a 'limp home' mode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the shift demand sensor fails, then the marine drive cannot receive operator input to control gear position, but the system becomes inoperable and the operator is locked in a specific gear with no ability to shift

Engineering Contradiction:

Improvesystem operability after sensor failureVSAvoidability to control gear position

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The throttle demand sensor is made multi-functional by using it for both throttle control and shift control when the shift demand sensor fails. The control module detects sensor failure and reconfigures the system to use throttle demand lever positions as shift command positions, allowing the same sensor to perform multiple functions and maintain system operability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The control module changes the functional parameters of the throttle demand sensor by reinterpreting throttle demand lever positions as shift command positions. This parameter change allows the system to operate in a degraded mode where the throttle sensor provides shift control functionality, transforming the system's operational parameters to maintain usability after failure.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If the system uses a dedicated shift demand sensor for gear position control, then shift control precision is improved, but the system loses redundancy and becomes severely limited when the sensor fails

Engineering Contradiction:

Improveshift demand detection accuracyVSAvoidsystem adaptability after sensor failure

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The throttle demand sensor is designed to serve dual purposes: normal throttle control and emergency shift control. When the dedicated shift demand sensor fails, the system adapts by using the throttle demand sensor for shift commands, demonstrating multi-functionality that enhances system adaptability without compromising normal operational precision.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system prepares for potential sensor failure by establishing a backup control mode in advance. The control module is programmed to detect sensor failures and automatically switch to using the throttle demand sensor for shift control, providing beforehand cushioning that ensures continued operability and adaptability when the dedicated shift sensor fails.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If the system allows continued operation after shift demand sensor failure, then system reliability is improved, but the operator experiences limited control and must operate in a 'limp home' mode

Engineering Contradiction:

Improvecontinued operation capabilityVSAvoidoperator control authority

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The system implements partial control functionality by allowing shift commands to be issued through the throttle demand lever at predetermined positions. While this provides limited control authority compared to a fully functional shift demand sensor, it enables sufficient operation for the operator to navigate to a safe port, accepting partial action as a trade-off for maintaining continued operability.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The system accepts degraded performance as a temporary state, allowing operation in 'limp home' mode until the failed sensor can be replaced. The control module enables limited shift control functionality that suffices for getting the vessel to safety, treating the degraded operational state as a temporary solution rather than requiring immediate system shutdown.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS10155578B1Method and system for controlling a marine drive during shift sensor fault

Publication Date: 2018.12.18 BRUNSWICK CORP

AI summary

A system for controlling propulsion of a marine vessel by a marine drive is provided, the marine drive having a marine engine that effectuates rotation of propulsor through a shift system that shifts amongst at least a forward gear position, a reverse gear position, and a neutral position. The system includes a remote control having a lever movable to provide a throttle demand input for controlling the marine engine and a shift demand input for controlling the shift system. A shift demand sensor measures a shift demand lever position to provide the shift demand input, and a throttle demand sensor measures a throttle demand lever positions to provide the throttle demand input. A control module is configured to detect shift demand sensor failure based on the shift demand lever position values and assign a predetermined throttle demand lever position as shift command position. When the throttle demand lever position reaches the shift command position, a shift command is generated instructing a change in gear position of the shift system.