Variable Compression Release Valve for Engine Coasting
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Solution Overview
Problem
Internal combustion engines with compression release mechanisms face high energy consumption and significant pumping losses, especially at high engine speeds, which hampers efficient inertial energy utilization during coasting with fuel cut off.
Innovation Solution
A controller system that variably controls the opening degree of the compression release mechanism's valve member, increasing it at higher engine speeds to reduce energy consumption and pumping losses, while also adjusting the exhaust valve timing to prevent interference and optimize deceleration torque generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the valve opening degree of the compression release mechanism is made smaller to suppress energy consumption, then energy consumption for opening the valve member is reduced, but significant pumping losses occur in the region of high engine speed and inertial energy cannot be utilized effectively
Solution Approach 1:
The valve opening degree is made variable rather than fixed, allowing the compression release mechanism to adapt its opening degree according to engine speed conditions. The controller increases the opening degree at high engine speeds to reduce pumping losses and enable effective inertial energy utilization, while maintaining smaller opening degrees at low speeds to minimize energy consumption for valve operation.
Solution Approach 2:
The opening degree parameter of the valve member is dynamically adjusted based on engine speed. By changing this parameter according to operating conditions, the system optimizes the balance between energy consumption for valve operation and pumping losses, with higher opening degrees deployed at high speeds where pumping losses would otherwise be significant.
2Loss of energy
If the valve opening degree is increased to reduce pumping losses at high engine speed, then inertial energy utilization is improved, but energy consumption for operating the compression release mechanism increases
Solution Approach 1:
The system employs dynamic control of the valve opening degree that responds to engine speed conditions. Rather than maintaining a constantly large opening degree, the controller adjusts the opening degree in real-time, increasing it only when engine speed is high enough to warrant the reduced pumping losses, thereby avoiding unnecessary energy consumption at lower speeds.
Solution Approach 2:
The compression release mechanism operates periodically based on engine cycles and speed conditions, with the valve opening degree being modulated according to the periodic variation in engine speed during coasting operations, enabling energy-efficient operation across different operating phases.
3Power
If the exhaust valve timing is retarded to optimize deceleration torque generation, then electric power regeneration is enhanced, but valve interference with piston may occur
Solution Approach 1:
The exhaust valve timing is made dynamically adjustable through variable valve timing mechanisms, allowing the timing to be retarded optimally for deceleration torque generation during coasting with fuel cut off, while preventing excessive retardation that would cause valve-piston interference. The system adapts timing based on engine speed and load conditions.
Solution Approach 2:
The variable valve timing mechanism preemptively adjusts exhaust valve timing to prevent interference conditions before they occur. By controlling the extent of timing retardation based on predicted operating conditions, the system avoids valve-piston contact while still achieving optimal deceleration torque for electric power regeneration.
Data Source
AI summary
An apparatus for controlling an internal combustion engine is provided. An engine includes a compression release mechanism and a fuel injection valve. The compression release mechanism variably controls the opening degree of a valve member, and thereby connects the combustion chamber of the engine with at least one of the intake passage and the exhaust passage in order to release in-cylinder pressure during at least the compression stroke. A controller controls the fuel injection valve to execute coasting with the fuel cut off in which the fuel is cut off under a predetermined condition, and while executing coasting with the fuel cut off, controls the compression release mechanism to increase the opening degree of the valve member of the compression release mechanism as the speed of the engine is higher.