Split Cycle Engine Valve Timing for Engine Braking
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Solution Overview
Problem
Split cycle internal combustion engines lack an efficient mechanism to transition between active driving mode and engine braking mode, leading to inefficient energy utilization and increased wear on vehicle components.
Innovation Solution
A split cycle internal combustion engine design that includes a controller to adjust the positions of inlet and outlet valves to switch between active and engine braking modes, allowing for further compression of working fluid in the combustion cylinder without combustion, and utilizing a recuperator bypass passage to manage temperature and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the engine operates in active driving mode using conventional valve timing, then the engine can generate driving force, but energy is wasted during engine braking and wear increases on vehicle components
Solution Approach 1:
The patent implements dynamic valve timing adjustment that changes valve opening/closing positions based on the engine's operational mode. In active mode, conventional timing is used for power generation. In engine braking mode, the controller adjusts the inlet valve to open closer to BDC and the outlet valve to open closer to TDC, enabling the same physical hardware to adapt its timing characteristics dynamically to optimize energy recovery during braking while maintaining ease of operation through automated controller management
2Use of energy by moving object
If the outlet valve opens closer to TDC in engine braking mode, then further compression of working fluid is achieved, but the device complexity increases due to controller intervention
Solution Approach 1:
The patent changes the operational parameters of the valve system by adjusting opening and closing positions based on operational mode. The controller modifies timing parameters (inlet valve opens closer to BDC, outlet valve opens closer to TDC during engine braking) to achieve further compression of working fluid and harness energy during engine braking, transforming a simple engine into one that can recover energy during braking events
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 engine braking while reducing wear on vehicle components, harnessing energy for pressurized gas storage and improving overall energy efficiency by optimizing valve timing and temperature control.
Implementation Method 1
an inlet valve configured to control intake of compressed working fluid into the combustion cylinder
Implementation Method 2
an outlet valve configured to control exhausting of fluid from the combustion cylinder
Implementation Method 3
a compression cylinder accommodating a compression piston configured to provide compressed working fluid
Implementation Method 4
working fluid is being further compressed in the combustion cylinder for a majority of the movement of the combustion piston from its BDC position to its TDC position
Implementation Method 5
a controller configured to change the position during the engine cycle at which the inlet and/or outlet valves open to switch operation of the engine between an active mode and an engine braking mode
Data Source
AI summary
A split cycle internal combustion engine comprising: a compression cylinder accommodating a compression piston configured to provide compressed working fluid; a combustion cylinder accommodating a combustion piston, wherein the combustion cylinder is coupled to the compression cylinder to receive compressed working fluid therefrom, and wherein the combustion cylinder comprises: (i) an inlet valve configured to control intake of compressed working fluid into the combustion cylinder, and (ii) an outlet valve configured to control exhausting of fluid from the combustion cylinder, and a controller configured to change the position during the engine cycle at which the inlet and/or outlet valves open to switch operation of the engine between an active mode and an engine braking mode, wherein the controller is configured to control at least one of: the inlet valve to open at a position which is closer to a bottom dead centre, BDC, position when operating in the engine braking mode than when operating in the active mode; and the outlet valve to open at a position which is closer to a top dead centre, TDC, position when operating in the engine braking mode than when operating in the active mode.