Variable Valve Timing Control Device Noise Reduction

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Solution Overview

Problem

The variable valve timing mechanism experiences a decrease in controllability due to noise generated in the motor manipulated variable caused by stepwise changes in rotational phase measurement during calibration, leading to significant changes in the derivative term.

Innovation Solution

A control device and method that calibrate the rotational phase measurement based on the relative relationship between the crankshaft and camshaft angles, reducing the change in the derivative term by using the previous value of the derivative term during calibration to stabilize the motor manipulated variable.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the rotational phase is obtained by calibrating the rotational angle of the motor based on the relative relationship between the rotational angle of the crankshaft and that of the camshaft, then both responsiveness and accuracy in determination are improved, but noise is generated in the motor manipulated variable due to stepwise changes in measurement

Engineering Contradiction:

Improverotational phase measurement accuracyVSAvoidnoise in manipulated variable

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

A low-pass filter is introduced as an intermediary element between the derivative term calculation and the manipulated variable output. The filter processes the derivative term to remove high-frequency noise components while preserving the essential control information, thereby eliminating the harmful noise generation during calibration without compromising measurement accuracy

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies different filtering parameters based on operating conditions. During calibration processes, enhanced filtering is applied to suppress noise, while during normal operation, the filter parameters are adjusted to maintain responsiveness. This dynamic parameter adjustment resolves the contradiction between noise suppression and control responsiveness

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If the measurement of the rotational phase changes in a stepwise manner due to the calibration process, then the rotational phase can be accurately determined, but the derivative term proportional to the rate of change in the deviation greatly changes

Engineering Contradiction:

Improverotational phase measurement accuracyVSAvoidderivative term stability

Core Design Contradiction:

Measurement precisionVSStability of the object's composition

Solution Approach 1:

The low-pass filter serves as a mediator that smooths the stepwise changes in the derivative term. By introducing this filtering intermediary, the patent maintains the accuracy of rotational phase measurement during calibration while preventing the derivative term from exhibiting excessive fluctuations, thereby achieving stability in the control signal

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The filter is applied in advance to the derivative term calculation, cushioning against the potential instability caused by stepwise changes during calibration. This preemptive filtering ensures that even when calibration causes measurement adjustments, the resulting derivative term remains stable and does not generate noise in the manipulated variable

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If noise is generated in the manipulated variable of the motor, then the calibration process can be completed, but the controllability of the variable valve timing mechanism decreases

Engineering Contradiction:

Improvecalibration process completionVSAvoidcontrollability of variable valve timing mechanism

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The low-pass filter acts as a protective intermediary that allows the calibration process to complete while preventing noise from reaching the manipulated variable output. This mediator enables the system to undergo calibration adjustments without compromising the reliability and controllability of the variable valve timing mechanism during or after calibration

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the potentially harmful stepwise changes during calibration into beneficial controlled adjustments. By applying the low-pass filter, the calibration process can proceed to update rotational phase measurements accurately, while the filter simultaneously transforms the noisy derivative term into a stable control signal, thereby maintaining controllability throughout the calibration process

Inventive Principle:

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

Data Source

PatentUS11230988B2Control device and control method for variable valve timing mechanism

Publication Date: 2022.01.25 ASTEMO LTD

AI summary

A control device and a control method for variable valve timing mechanism according to the present invention obtains a first measurement of a rotational phase based on a rotational angle of the motor, obtains a second measurement of the rotational phase based on a relative relationship between a rotational angle of the crankshaft and a rotational angle of the camshaft, calibrates the first measurement based on the second measurement, obtains a derivative term proportional to a rate of change in a deviation between the first measurement and a target value, reduces change in derivative term when calibrating the first measurement based on the second measurement, and controls the motor based on a manipulated variable including the derivative term.