Electric Cam Phaser Position Sensing via Hall Effect Sensors

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Solution Overview

Problem

Existing camshaft position sensing technologies, such as vane-type cam phasers, face challenges at low engine speeds and low temperatures due to low oil pressure and viscosity issues, leading to slow response and increased fuel consumption, and they require additional components for accurate positioning, especially at zero RPM.

Innovation Solution

A method utilizing a gear reduction mechanism with a predetermined gear reduction ratio and Hall Effect sensors to determine the rotational position of the electric motor, which calculates the camshaft position, eliminating the need for additional components and enabling accurate positioning even at zero RPM.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a vane-type cam phaser is used for camshaft positioning, then the structure is simple and cost-effective, but the response is slow at low engine speeds and low temperatures due to high oil viscosity and low oil pressure

Engineering Contradiction:

Improvestructural simplicityVSAvoidresponse speed

Core Design Contradiction:

Ease of manufactureVSSpeed

Solution Approach 1:

The patent replaces the oil-pressure-driven mechanical vane-type cam phaser with an electrically-driven cam phaser that uses a motor and gear mechanism. This substitution eliminates the dependency on oil pressure and viscosity, allowing the system to respond quickly at low engine speeds and low temperatures without being constrained by fluid dynamics limitations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Speed

If a vane-type cam phaser is used, then additional oil pump capacity is required for fast actuation, but this increases fuel consumption

Engineering Contradiction:

Improveactuation speedVSAvoidfuel consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The patent replaces the oil-pressure-based actuation system with an electric motor-driven system. This allows fast actuation to be achieved through electrical power delivery rather than mechanical oil pump capacity, eliminating the need for oversized oil pumps and the associated fuel consumption penalty while maintaining rapid response capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If a target wheel with slots is used for camshaft position sensing, then the position can be detected, but one complete revolution is required to synchronize and establish position

Engineering Contradiction:

Improveposition detection accuracyVSAvoidsynchronization time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the mechanical target wheel with slots sensing method with an electronic position sensing system using Hall effect sensors or magnetic sensors. This electronic approach allows immediate position detection without requiring mechanical rotation or synchronization, eliminating the time loss associated with waiting for a complete revolution to establish position.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Device complexity

If engine oil is used to drive the cam phaser, then the system is parasitic on the oil system, but using alternative drive methods increases device complexity

Engineering Contradiction:

Improvesystem simplicityVSAvoidsystem independence

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent replaces the oil-pressure-driven mechanical system with an electrically-driven system. This substitution creates system independence from the oil system, eliminating parasitic effects on oil pressure and consumption. The electric motor and gear mechanism provide direct actuation without requiring oil flow, achieving both simplicity and independence simultaneously.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution allows for quick and accurate determination of the camshaft position without additional components, improving response times and reducing fuel consumption by leveraging the electric variable cam phaser's ability to function reliably at low engine speeds and temperatures, and enabling precise control of valve timing.

Implementation Method 1

typically, three Hall Effect sensors are used to detect the position of a rotor of the motor

Methodology Applied

Scientific EffectHall Effect: Hall Effect

Data Source

PatentUS8682564B2Camshaft position sensing in engines with electric variable cam phasers

Publication Date: 2014.03.25 BORGWARNER US TECHNOLOGIES LLC

AI summary

A method is provided for sensing the position of a camshaft in an internal combustion engine having a camshaft phaser for controllably varying the phase relationship between a crankshaft of the internal combustion engine and the camshaft, the camshaft phaser being actuated by an electric motor and having a gear reduction mechanism with a predetermined gear reduction ratio and a sensor for determining the rotational position of the electric motor. The method includes generating a rotational position signal indicative of the rotational position of the electric motor by using the sensor to determine the rotational position of the electric motor and calculating the position of the camshaft based on the rotational position signal and the gear reduction ratio of the gear reduction mechanism.