CVVT and CVVD Valve Timing Control

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Solution Overview

Problem

Existing methods for controlling valve timing and duration in internal combustion engines using continuously variable valve timing (CVVT) and continuously variable valve duration (CVVD) systems face challenges in achieving optimal valve timing and duration adjustments, leading to inefficient engine performance at varying speed ranges.

Innovation Solution

A method and system that utilize a processor to determine desired valve opening and closing times, calculate desired valve duration, and control CVVT and CVVD apparatuses to achieve optimal valve timing and duration by adjusting valve lift and timing independently, allowing for real-time adjustments to valve opening and closing times.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If valve timing is adjusted to be retarded for low rpm operation, then expansion and explosion of mixture is improved, but discharge of mixture is delayed at high speed

Engineering Contradiction:

Improveengine power at low rpmVSAvoidvalve discharge speed at high rpm

Core Design Contradiction:

PowerVSSpeed

Solution Approach 1:

The patent implements dynamic adjustment of valve timing using a CVVT (Continuously Variable Valve Timing) apparatus that can continuously change the phase angle between camshaft and crankshaft. This allows the valve timing to be optimized for low-speed power generation while preventing high-speed discharge delays, resolving the contradiction between low-rpm expansion efficiency and high-rpm discharge speed

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the valve timing parameter dynamically based on operating conditions. By adjusting the phase angle parameter through hydraulic control in the CVVT apparatus, the valve timing can be optimized for different engine speeds, achieving both low-speed power and high-speed discharge requirements

Inventive Principle:

Principle #35Parameter changes

2Speed

If valve timing is adjusted to be advanced for high rpm operation, then discharge of mixture is improved, but compression of mixture is delayed at low speed

Engineering Contradiction:

Improvevalve discharge speed at high rpmVSAvoidengine power at low rpm

Core Design Contradiction:

SpeedVSPower

Solution Approach 1:

The CVVT apparatus enables dynamic reversal of valve timing adjustment based on operating conditions. At high rpm, the phase angle is advanced to improve discharge speed, while at low rpm, it is retarded to maintain compression and power, thus resolving the contradiction between high-speed discharge and low-speed compression

Inventive Principle:

Principle #15Dynamics

3Ease of operation

If CVVL system varies valve duration, then valve lift control is improved, but degree of freedom in control is reduced

Engineering Contradiction:

Improvevalve lift controlVSAvoidcontrol degree of freedom

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent separates the control of valve timing and valve duration into two independent systems: CVVT for timing control and CVVD for duration control. This segmentation allows each parameter to be optimized independently without interfering with the other, maintaining full control freedom while achieving both timing and duration optimization

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The combined CVVT-CVVD system provides multi-functional control capability, handling both valve timing and valve duration optimization simultaneously. This universal control system resolves the limitation of CVVL by adding independent timing control while maintaining duration control capabilities

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Ease of operation

If valve duration is varied using CVVD, then valve timing control is improved, but desired valve timing cannot be obtained due to timing change

Engineering Contradiction:

Improvevalve duration controlVSAvoidvalve timing accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The system employs feedback control where the actual valve timing is monitored and compared with the desired timing. The CVVT apparatus adjusts the phase angle based on this feedback to compensate for any timing deviations caused by CVVD operation, ensuring the desired valve timing is achieved despite duration variations

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary timing adjustment through CVVT before or during CVVD operation. By pre-setting the phase angle compensation, the system ensures that when valve duration is varied, the valve timing remains accurate, preventing timing errors before they occur

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10330026B2Method of controlling valve timing and valve duration using CVVT apparatus and CVVD apparatus

Publication Date: 2019.06.25 HYUNDAI MOTOR CO LTD

AI summary

A method of controlling valve timing and valve duration using a CVVT apparatus and a CVVD apparatus, the CVVT apparatus being configured to adjust an opening time of a valve in a vehicle engine, the CVVD apparatus being configured to adjust a duration of a valve lift, the method may include determining a desired valve opening time and a desired valve closing time; determining a desired valve duration by the desired valve opening time and the desired valve closing time; determining a desired valve timing through the desired valve opening time and an actual valve duration measured in real time; and controlling the CVVD apparatus to accomplish the desired valve duration while controlling the CVVT apparatus to accomplish the desired valve timing.