Variable Intake Valve Actuation for Mild-Hybrid Pumping Loss Reduction
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Solution Overview
Problem
Mild-hybrid motor vehicle power propulsion systems face inefficiencies due to pumping losses when the internal combustion engine is driven by the BAS unit, leading to excessive energy loss and low performance in e-motoring modes.
Innovation Solution
Implementing a system for variable actuation of intake valves, such as the MULTIAIR system, which allows for advanced control of intake valve opening and closing times to minimize pumping losses by using solenoid valves to decouple the valves from the camshaft, and optionally opening valves during the exhaust phase to recirculate exhaust gases, reducing energy waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the internal combustion engine is driven by the BAS unit in e-motoring mode, then the BAS unit can provide propulsion, but pumping losses occur due to the engine being in cut-off condition
Solution Approach 1:
The patent applies dynamics by making the valve actuation system adjustable and adaptive. The camshaft profile can be dynamically changed via solenoid valves that control hydraulic pressure in the tappets, allowing the intake valves to be decoupled from the camshaft when needed. This dynamic adjustment enables the system to optimize performance for e-motoring conditions by minimizing pumping losses while maintaining propulsion capability.
Solution Approach 2:
The patent changes the operational parameters of the valve actuation system. By controlling the solenoid valves, the system alters the hydraulic pressure states in the tappets, which changes the valve lift profiles and timing. This parameter change allows the intake valves to remain closed or partially open during e-motoring, reducing the pumping effect and energy losses while the engine shaft continues to rotate.
2Loss of energy
If the intake valves are decoupled from the camshaft using solenoid valves, then pumping losses are reduced, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing the valve actuation system to perform multiple functions. The same hydraulic tappet system with solenoid valves that provides variable valve actuation for combustion modes also enables the decoupling function for e-motoring mode. This multi-functionality reduces the need for separate mechanisms, thereby limiting the increase in device complexity while achieving pumping loss reduction.
Solution Approach 2:
The system uses the existing hydraulic infrastructure of the valve actuation mechanism to achieve decoupling. The solenoid valves utilize the hydraulic pressure already present in the tappets to control valve timing, rather than requiring a separate mechanical decoupling mechanism. This self-service approach leverages existing system components to reduce energy losses, minimizing the added complexity.
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 approach significantly reduces pumping losses, enabling efficient operation with the BAS unit as the sole propulsion engine, enhancing performance and reducing fuel consumption by minimizing energy wastage during e-motoring conditions.
Implementation Method 1
The tappet is connected to the intake valve through hydraulic actuation means comprising a pressure hydraulic chamber, which can be connected to an exhaust channel through an electronically controlled solenoid valve
Data Source
AI summary
In a vehicle provided with a power propulsion system of the mild-hybrid type, a BAS unit—including an electric machine connected through a belt transmission to the shaft of an internal combustion engine—is exploited as the only propulsion engine of the vehicle in given operating conditions. The internal combustion engine is provided with a system for variable actuation of the intake valves which is controlled to reduce the pumping losses of the internal combustion engine in the phase in which such engine is in cut-off condition and it is driven by the aforementioned BAS unit. It is also provided for that the system for variable actuation of the intake valves be controlled to temporarily increase the pumping losses of the internal combustion engine in a phase in which it is required to accelerate the switching off of the engine.