Electric Motor Variable Valve Timing Control
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Solution Overview
Problem
Existing variable valve timing systems face challenges in accurately controlling valve timing, especially in cold environments or during engine starting, due to insufficient hydraulic pressure and slow camshaft response, leading to increased processing load on control units.
Innovation Solution
A variable valve timing system that utilizes an electric motor as an actuator, with a dual-controller configuration where one controller calculates the valve timing based on sensor inputs and sets a rotational speed command, and the other controller controls the electric motor's power supply to achieve high-speed valve timing control without excessive processing load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydraulic system is used to drive the camshaft, then the system structure is simple, but the valve timing control accuracy is insufficient and response is slow in cold environments or during engine starting
Solution Approach 1:
The patent replaces the hydraulic drive system with an electric motor-driven system. The electric motor directly drives the camshaft through a reduction mechanism, eliminating the hydraulic system's dependency on fluid pressure and pump operation. This substitution enables faster response and more accurate control, especially in cold conditions where hydraulic fluid viscosity increases and pressure buildup is delayed.
Solution Approach 2:
The patent implements variable valve timing control by dynamically adjusting the camshaft phase angle through electric motor control. The system can rapidly change the camshaft position based on real-time engine conditions, enabling adaptive valve timing that optimizes performance across different operating conditions, including cold start and idle operations.
2Extent of automation
If the VVT ECU performs multiple functions including target value setting and control signal generation, then the valve timing control can be integrated, but the processing load on the ECU excessively increases
Solution Approach 1:
The patent divides the control system into separate functional modules: a VVT ECU that calculates target valve timing values based on engine conditions, and a dedicated motor control unit that generates control signals for the electric motor. This segmentation reduces the processing burden on each individual controller while maintaining integrated automation, as each unit focuses on specific tasks rather than attempting to perform all control functions.
3Measurement precision
If feedback control is implemented to match actual valve timing with desirable timing, then the control accuracy improves, but the processing load on the control unit excessively increases
Solution Approach 1:
The patent segments the feedback control function into two parts: the VVT ECU measures actual valve timing using sensors and compares it with target values to calculate timing deviations, while the motor control unit receives these deviations and generates appropriate motor control signals. This division allows accurate feedback control to be implemented without overloading a single controller, as each unit performs only its specific portion of the control loop.
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 configuration enables high-speed valve timing control by efficiently managing the electric motor's rotational speed, reducing processing load on controllers and improving accuracy and responsiveness, particularly in challenging conditions.
Implementation Method 1
a variable valve timing system that uses an electric motor as an actuator
Data Source
AI summary
A valve timing control is executed by an ECU that controls an engine and an electric-motor ECU that controls an electric motor. The ECU and the electric-motor EDU serve different functions. The ECU sets the target phase of an intake valve based on the engine operating state, and prepares a rotational speed command value for the electric motor that serves as an actuator such that a phase feedback control loop, in which the intake valve phase is caused to match the target phase, is formed. The electric-motor EDU forms a feedback control loop for the motor speed, in which the electric power supplied to the electric motor is controlled such that the electric motor rotates in accordance with the rotational speed command value.