Engine Braking via Phase-Shifted Exhaust Valve Timing
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Solution Overview
Problem
Existing four-stroke internal combustion engines face challenges in achieving efficient engine braking while maintaining optimal gas temperature control, which can lead to suboptimal performance and increased reductant consumption in exhaust aftertreatment systems during long-lasting engine braking operations.
Innovation Solution
The implementation of a four-stroke internal combustion engine with phase-shifted exhaust and inlet valve control mechanisms, where exhaust valves are opened during the expansion stroke and closed during the exhaust stroke, and inlet valves are phase-shifted to regulate air flow, ensuring efficient engine braking and maintaining suitable gas temperatures to support the operation of exhaust aftertreatment systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If exhaust valves are opened during exhaust stroke in conventional engine braking, then engine structure is simple, but braking torque is insufficient and gas temperature control is poor
Solution Approach 1:
The patent applies dynamics by making the valve control mechanism adjustable and variable. The valve control arrangement is configured to phase-shift control of exhaust valves dynamically, allowing the system to adapt valve timing based on operating conditions. This transforms the static valve control into a dynamic system that can optimize braking torque and gas temperature control根据不同工况
Solution Approach 2:
The patent changes the timing parameter of exhaust valve control through phase-shifting. By adjusting the phase-shift angle of exhaust valve control relative to the crankshaft position, the system optimizes the timing of exhaust valve opening and closing during engine braking. This parameter change enables better control over gas temperature and braking torque without fundamental structural changes
2Temperature
If phase-shifted exhaust valve control is implemented, then gas temperature control improves, but valve control complexity increases
Solution Approach 1:
The valve control arrangement performs multiple functions: it controls exhaust valve timing for both power operation and engine braking, provides phase-shifting capability, and manages gas temperature control. By making the valve control arrangement multi-functional, the patent reduces the need for separate dedicated systems for each function, thereby managing complexity while achieving temperature control
3Temperature
If inlet valves are phase-shifted to regulate air flow, then gas temperature control improves, but control system complexity increases
Solution Approach 1:
The patent merges the control of inlet and exhaust valves into a coordinated phase-shifting system. Both inlet valve control arrangement and exhaust valve control arrangement work together with phase-shifting capabilities, allowing simultaneous regulation of air flow and exhaust gas temperature. This integration reduces overall system complexity compared to having separate independent control systems
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 solution provides enhanced engine braking torque and maintains the temperature of exhaust aftertreatment systems within a suitable range, reducing reductant consumption and ensuring environmental sustainability by optimizing gas temperature and air flow during engine braking.
Implementation Method 1
As a piston travels upward during its compression stroke, the gases that are trapped in the cylinder are compressed. The compressed gases oppose the upward motion of the piston.
Implementation Method 2
The inlet valve control arrangement comprises an inlet valve phase-shifting device configured to regulate the amount of air pumped through the engine during the engine braking by regulating the phase-shift of the at least one inlet valve
Data Source
Figure 1
Figure 2a~2c
Figure 2d~2f
AI summary
Herein a four-stroke internal combustion engine (1) is disclosed comprising an exhaust valve control arrangement (28) with an exhaust valve phase-shifting device (30) configured to phase-shift control of the at least one exhaust valve (24) to a state where the at least one exhaust valve (24) is controlled in such a way that it is opened during the expansion stroke of the engine (1) and closed during the exhaust stroke of the engine (1), in order to achieve engine-braking via compression in the cylinders (10) during the exhaust stroke. An inlet valve control arrangement (22) comprises an inlet valve phase-shifting device (32) configured to regulate the amount of air pumped through the engine (1) during the engine braking by regulating the phase-shift of the at least one inlet valve (18). The present disclosure also relates to a vehicle comprising an engine (1) and method of controlling an engine (1), a computer program and a computer program for performing a method of controlling an engine (1).