Variable Actuation of Internal-Combustion Engine Valves
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Solution Overview
Problem
Current engine valve actuation systems for internal-combustion engines are limited in their ability to efficiently operate across a wide range of compression ratios, especially high values, and do not effectively reduce pumping work or allow for smaller engine dimensions while maintaining power delivery, nor can they seamlessly transition between four-stroke and two-stroke modes without mechanical cam selection mechanisms.
Innovation Solution
A hydraulic system with a dual cam profile and solenoid valve configuration that allows selective actuation of engine valves in both four-stroke and two-stroke modes based on engine load conditions, using a single hydraulic apparatus to drive slave pistons and control valve lift and timing independently of the camshaft motion, enabling adaptive control of valve operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single cam profile is used for valve actuation, then the device complexity is reduced, but the adaptability to different operating modes (four-stroke and two-stroke) is limited
Solution Approach 1:
The camshaft is designed with two different cam profiles on the same physical component, allowing it to serve multiple functions by governing valve actuation in both four-stroke and two-stroke operating modes. This eliminates the need for separate camshafts or complex switching mechanisms while maintaining adaptability to different engine cycles.
Solution Approach 2:
The hydraulic apparatus dynamically switches between following the cam profile and operating independently through solenoid valve control. This dynamic capability allows the system to adapt to different operating modes (four-stroke/two-stroke) and compression ratios without mechanical changes to the camshaft itself.
2Adaptability or versatility
If the hydraulic apparatus operates independently from the camshaft, then the adaptability to vary valve lift and timing is improved, but the device complexity increases due to additional control mechanisms
Solution Approach 1:
The solenoid valve acts as an intermediary between the hydraulic apparatus and the camshaft. It controls the connection between the master and slave pistons, enabling the hydraulic system to either follow the cam profile or operate independently. This intermediary component provides precise control with minimal additional complexity.
Solution Approach 2:
The system replaces purely mechanical cam-based valve actuation with a hybrid hydraulic-electronic system. The solenoid valve (electronic) controls hydraulic pressure to the slave piston, substituting direct mechanical coupling with controllable fluid pressure actuation for enhanced adaptability.
3Productivity
If the engine operates in two-stroke mode with high compression ratios, then the power density and efficiency are improved, but the reliability and control precision of valve timing are worsened
Solution Approach 1:
The control unit receives input from sensors monitoring engine operating conditions and adjusts solenoid valve actuation accordingly. This feedback loop ensures precise valve timing control in two-stroke mode, maintaining accuracy despite the challenging high-compression operating conditions and enabling optimal power density.
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
Enables efficient engine operation across a wide range of compression ratios, reduces pumping work, allows for smaller engine designs, and facilitates seamless mode switching between four-stroke and two-stroke operations, optimizing engine efficiency and performance by varying valve opening, closing, and lift based on real-time engine conditions.
Implementation Method 1
a solenoid valve (60) configured for assuming a state in which said second volume of fluid (V2) is set in communication with an outlet (66) so as to render said slave piston (52) independent from the movement of said second master piston (48) through the electromagnetic force of its mobile member (67)
Implementation Method 2
a hydraulic apparatus including: a master piston (46, 48); a slave piston (52) that can be driven by said master piston (46, 48) through the fluid pressure of a volume of fluid (V, V1) set between said master piston (46, 48) and said slave piston (52)
Data Source
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AI summary
Described herein is a system for variable actuation of an engine valve of an internal-combustion engine, which is characterized in that it is able to actuate the engine valves, selectively, in a four-stroke operating mode and in a two-stroke operating mode, on the basis of the operating conditions of the engine.