Variable Valve Timing Control System for Internal Combustion Engines
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Solution Overview
Problem
Existing systems for modifying inlet valve timing in internal combustion engines are mechanically complex, require hydraulic energy, and suffer from limited torque continuity and slow response times, especially in electric engines.
Innovation Solution
A control system using two camshafts per cylinder, where a basic camshaft controls the first inlet and exhaust valves, and a control camshaft manages the second inlet and exhaust valves, with an electronic control unit, motor/generator unit, differential, actuator, and solenoids to adjust valve timing dynamically based on engine load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple cams with different lifts and opening times are used to modify inlet valve timing, then engine performance at mid- and low-range torque is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic valve timing control by making the inlet valve lift variable through a mechanism that allows the valve to follow different cam profiles (first cam for high lift, second cam for low lift) based on engine operating conditions. This dynamic adjustment enables optimization of engine performance across different torque ranges without requiring multiple fixed valve train systems.
Solution Approach 2:
The patent creates a universal valve control system where a single inlet valve serves multiple functions by being able to follow different cam profiles. The valve can operate in high-lift mode for maximum performance, low-lift mode for efficiency, or intermediate positions, making one valve component perform the work that would traditionally require multiple dedicated valves or complex mechanical selection systems.
2Adaptability or versatility
If hydraulic control is used to actuate valve timing changes, then adaptability to different torque conditions is improved, but response time decreases
Solution Approach 1:
The patent replaces hydraulic control mechanisms with a mechanical control system that uses a control cam and follower mechanism to directly actuate the inlet valve. This mechanical substitution eliminates the delays inherent in hydraulic fluid transmission and compression, providing immediate response to valve timing requirements while maintaining the ability to adapt to different torque conditions through cam profile selection.
3Use of energy by moving object
If the inlet valve closes early to reduce air intake volume, then fuel consumption is reduced, but pumping losses increase
Solution Approach 1:
The patent implements dynamic control of inlet valve timing and lift, allowing the valve to close at optimized moments and maintain controlled opening durations. By making the valve lift and timing variable rather than fixed, the system can reduce air intake volume to lower fuel consumption while simultaneously managing pumping losses through precise control of valve event timing and duration based on real-time engine operating conditions.
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 system reduces pumping losses, improves engine performance under partial load conditions, and enhances fuel efficiency without affecting maximum power output, while simplifying the mechanical design and improving torque continuity and response speed.
Implementation Method 1
a control system with camshafts, wherein a phase shift is provided, in each cylinder, upon opening, upon closing or in both cases, the second inlet valve with respect to the first
Implementation Method 2
a control system with camshafts, wherein a phase shift is provided, in each cylinder, upon opening, upon closing or in both cases, the second inlet valve with respect to the first
Data Source
AI summary
A control system for internal combustion engines having four valves per cylinder. An inlet valve and an exhaust valve are controlled by a basic camshaft. Another inlet valve and another exhaust valve are controlled by a control camshaft. The two camshafts are connected to a crankshaft and engine torque is managed by an electronic control unit. The system comprises a motor/generator unit, connected to the control camshaft; a differential, connected to the crankshaft and to the control camshaft; a control shaft, connected to the differential; an actuator, connected to the control shaft; a one-way restrictor valve connected to a shut-off valve and to the actuator; an oil circuit, connected to the actuator by means of the shut-off valve and a control solenoid that acts on the shut-off valve.