Camshaft Position Detection Using Dual Sensor Algorithms

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Solution Overview

Problem

Internal combustion engines face challenges in accurately and quickly detecting the position of camshaft or crankshaft due to variations in rotational speed, leading to potential operating delays and misidentification of wheel position caused by noise in the signal.

Innovation Solution

A system comprising two position detection systems, each with a sensor associated with a rotatable wheel on a shaft, utilizing a pattern of targets and gaps to determine the angular position of the shaft, with a controller selecting the faster method between the two systems to ensure timely and accurate position identification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single position detection system is used, then the device complexity is low, but the reliability of position detection is insufficient under wide rotational speed variations

Engineering Contradiction:

Improveposition detection reliabilityVSAvoiddetection system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The position detection system is segmented into two independent detection algorithms: a first algorithm using a wheel with multiple targets and gaps, and a second algorithm using a wheel with consistent targets and one or more gaps. Each algorithm processes signals independently, and their results are combined to improve overall detection reliability under varying rotational speeds.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the parameters of the detection wheel by providing two different wheel configurations: one with multiple targets and gaps for normal operation, and another with consistent targets and fewer gaps for backup or alternative detection modes. This parameter variation allows the system to maintain reliability across different operational conditions.

Inventive Principle:

Principle #35Parameter changes

2Speed

If traditional single detection system is used, then the device complexity is low, but the detection speed is insufficient during engine cranking

Engineering Contradiction:

Improvedetection speedVSAvoiddetection system complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The controller is pre-configured with multiple detection algorithms and their corresponding processing logic. During engine cranking, the system can immediately switch between or combine these pre-prepared algorithms without requiring real-time system reconfiguration, thereby achieving fast detection response.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically selects or combines detection algorithms based on real-time operational conditions such as rotational speed variations. The controller can switch between the first detection algorithm (multiple targets) and second detection algorithm (consistent targets) depending on which provides faster or more reliable detection at the current moment.

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If signal processing is performed with noise filtering, then the measurement precision is improved, but the processing time increases causing operating delays

Engineering Contradiction:

Improveposition measurement accuracyVSAvoidprocessing time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system replaces complex mechanical signal filtering processes with algorithmic signal processing. The controller uses digital signal processing techniques to filter noise and determine wheel position, which can be performed faster and more accurately than traditional mechanical or analog filtering methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system creates multiple copies of the detection logic through different algorithms (first algorithm with multiple targets, second algorithm with consistent targets). These parallel processing paths allow the system to process signals simultaneously through different methods, selecting the fastest accurate result rather than sequentially applying multiple filters.

Inventive Principle:

Principle #26Copying

Data Source

PatentUS11639859B2Method for determining rotational position of a rotating camshaft on a reciprocating engine using a target with a pattern of teeth and a collection of detection algorithms

Publication Date: 2023.05.02 DEERE & CO

AI summary

Identifying position of a first rotating shaft may comprise a first position detection system and a second position detection system. A controller may be coupled to a first sensor and a second sensor and may identify the position of the first shaft using the identified shaft position from either the first detection system or the second detection system, whichever is identified faster. The first shaft may have a first wheel disposed thereon with targets and one or more gaps disposed about the first wheel. A second shaft may have a second wheel disposed thereon with targets and one or more gaps disposed thereon. The second wheel is in a fixed relationship relative to the first wheel. The first detection system may use data simultaneously from the first sensor and the second sensor to eliminate targets to determine position. The second detection system uses data only from the first sensor.