Dual Camshaft Engine Valve Control System
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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 phase shift and torque continuity issues, especially under varying load conditions.
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 solenoid system to adjust valve timing dynamically based on engine torque, reducing mechanical complexity and enhancing phase shift capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If hydraulic control systems with multiple cams are used to modify inlet valve timing, then fuel consumption is reduced under partial load, but device complexity increases and torque continuity is limited
Solution Approach 1:
The system divides the valve control into two independent camshafts: a basic camshaft for normal operation and a control camshaft for Atkinson cycle operation. Each camshaft controls specific valves independently, allowing seamless switching between operating modes without requiring complex mechanical switching mechanisms.
Solution Approach 2:
The patent replaces complex hydraulic control systems with a simpler mechanical differential mechanism. The differential automatically manages the phase relationship between the basic camshaft and control camshaft, eliminating the need for complex hydraulic actuators and switching mechanisms while maintaining continuous torque delivery.
2Loss of energy
If early inlet valve closing is used to reduce air intake, then pumping losses are reduced, but engine performance under maximum power is compromised
Solution Approach 1:
The system dynamically adjusts valve timing based on operating conditions. Under partial load, the control camshaft closes the inlet valve early to reduce pumping losses. Under maximum power demand, both camshafts work together to maintain optimal valve timing, ensuring full power output is available when needed.
Solution Approach 2:
The dual camshaft system serves multiple functions: the basic camshaft handles normal operation, while the control camshaft provides Atkinson cycle operation during partial load. Both camshafts can operate simultaneously or independently, allowing the system to adapt to different operating conditions and maintain both fuel efficiency and power capability.
3Loss of energy
If discrete valve timing diagrams are used, then fuel efficiency improves at specific operating points, but torque continuity is degraded
Solution Approach 1:
The differential mechanism continuously adjusts the phase relationship between the basic camshaft and control camshaft, enabling smooth transitions between different valve timing configurations. This continuous adjustment capability eliminates the discrete switching inherent in traditional systems, maintaining torque continuity while achieving fuel efficiency improvements across a range of 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 optimizes engine performance by reducing pumping losses and improving fuel efficiency under partial load conditions without compromising maximum power output, offering continuous torque adjustment and robust operation.
Implementation Method 1
a motor/generator unit (5), connected to the control camshaft (3)
Implementation Method 2
a differential (4), connected to the crankshaft (1) and to the control camshaft (3)
Implementation Method 3
a control solenoid (15) capable of acting on the shut-off valve (14)
Implementation Method 4
a one-way restrictor valve (13) connected, on the one hand, to the shut-off valve (14) and, on the other, to the actuator (7)
Data Source
Figure 1~2
Figure 3
Figure 4~6
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.