Cam Phaser Control for Auto-Stop Power Reduction

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Solution Overview

Problem

Existing camshaft phaser control systems in internal combustion engines face challenges in efficiently managing camshaft position during auto-stop/start events, leading to increased power consumption and temperature issues when continuously applying power to electric cam phasers, while disabling power results in suboptimal startup conditions and vibration.

Innovation Solution

A control system that uses an electric motor to phase the camshaft relative to the crankshaft, with a current module toggling power ON and OFF during auto-stop events to maintain the camshaft position closer to a predetermined position, reducing power consumption and temperature, and adjusting the position during startup for better engine performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If power is continuously applied to the electric cam phaser during auto-stop events, then the camshaft position is maintained precisely, but power consumption increases and temperature rises

Engineering Contradiction:

Improvecamshaft position control precisionVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies periodic action by alternating between active phasing mode (electric motor engaged) and coast mode (electric motor disengaged) during auto-stop events. The control system monitors camshaft position and selectively activates the electric motor only when position correction is needed, rather than maintaining continuous power application. This periodic engagement resolves the contradiction by achieving position maintenance through intermittent correction rather than continuous power consumption.

Inventive Principle:

Principle #19Periodic action

2Measurement precision

If power is continuously applied to the electric cam phaser during auto-stop events, then the camshaft position is maintained precisely, but temperature of the electric motor increases

Engineering Contradiction:

Improvecamshaft position control precisionVSAvoidelectric motor temperature

Core Design Contradiction:

Measurement precisionVSTemperature

Solution Approach 1:

Inventive Principle:

Principle #19Periodic action

3Use of energy by moving object

If power is disconnected from the electric cam phaser during auto-stop events, then power consumption decreases, but the camshaft position drifts from the predetermined position

Engineering Contradiction:

Improvepower consumptionVSAvoidcamshaft position accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The patent applies feedback by continuously monitoring camshaft position during auto-stop events and using this information to determine when to reactivate the electric motor. The control system compares the actual camshaft position against the target position and selectively engages the electric motor only when position deviation exceeds a threshold, creating a feedback-controlled intermittent operation mode that maintains position accuracy while reducing power consumption.

Inventive Principle:

Principle #23Feedback

4Use of energy by moving object

If the camshaft position is allowed to drift during auto-stop events, then power consumption decreases, but engine startup performance deteriorates with increased vibration

Engineering Contradiction:

Improvepower consumptionVSAvoidengine vibration during startup

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by proactively monitoring camshaft position during auto-stop events and reactivating the electric motor before significant position drift occurs. The control system uses feedback to detect early position deviations and corrects them by engaging the electric motor, preventing the camshaft from drifting to positions that would cause problematic engine startup conditions and vibration.

Inventive Principle:

Principle #10Preliminary action

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

This approach decreases power consumption and temperature of the electric cam phaser, provides better engine startups with reduced vibration, and maintains the camshaft position optimally during auto-stop/start events.

Implementation Method 1

an electric motor configured to phase rotation of an camshaft of an engine relative to rotation of a crankshaft of the engine

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentUS10954830B1Cam phaser control systems and methods for engine off conditions

Publication Date: 2021.03.23 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A control system of a vehicle includes: an electric motor configured to phase rotation of an camshaft of an engine relative to rotation of a crankshaft of the engine; a current module configured to, while the engine is off: selectively transition a current signal back and forth between a first state and a second state; and a motor driver module configured to, while the engine is off: apply power to the electric motor from a battery and adjust a position of the camshaft toward a predetermined position when the current signal is in the first state; and disconnect the electric motor from the battery and allow the position of the camshaft to move away from the predetermined position when the current signal is in the second state.