Compression Release Hydraulic Valve Actuator for CVVL Engine Restart
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vehicle engines equipped with stop/start systems face challenges in reducing fuel consumption and noise, vibration, and harshness (NVH) due to high restart torques, which limit the frequency of stop/start events and increase emissions.
Innovation Solution
Implementing a compression release hydraulic valve actuator in the CVVL system to adjust the valve position during engine restarts, reducing the torque required to restart the engine by providing compression release during the compression stroke, thereby reducing NVH and increasing fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine uses a stop/start system to reduce fuel consumption, then fuel efficiency is improved, but high restart torques increase noise, vibration, and harshness (NVH) and limit the frequency of stop/start events
Solution Approach 1:
The compression release hydraulic valve actuator is activated before the compression stroke to open the intake valve, allowing air to escape from the cylinder. This preliminary action reduces the compression pressure that would otherwise occur during engine restart, thereby reducing restart torque and associated NVH while enabling more frequent stop/start events
Solution Approach 2:
The patent extracts the harmful compression pressure from the cylinder by providing a release path through the open intake valve. By removing the compressed air before it builds up significant pressure, the system reduces the torque required for engine restart and minimizes NVH without compromising the fuel efficiency benefits of the stop/start system
2Use of energy by moving object
If the engine uses a stop/start system to reduce fuel consumption, then fuel efficiency is improved, but the frequency of stop/start events is limited due to high restart torques
Solution Approach 1:
The system performs preliminary compression release by opening the intake valve before the compression stroke, reducing the torque required for engine restart. This enables the stop/start system to be activated more frequently without exceeding torque limits, thereby increasing productivity in terms of stop/start event frequency while maintaining fuel efficiency improvements
3Power
If a larger electric machine is used to provide sufficient torque for engine restart, then restart capability is improved, but vehicle cost and complexity increase
Solution Approach 1:
The patent extracts the need for high restart torque by removing the compressed air from the cylinder through the compression release mechanism. This reduces the actual torque requirement for engine restart, allowing the use of a smaller, less complex electric machine while maintaining sufficient restart capability
Solution Approach 2:
By performing compression release before the compression stroke, the system preliminarily reduces the torque demand on the electric machine. This allows for downsizing the electric machine and associated belt drive system, reducing vehicle cost and complexity while maintaining adequate restart power
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 allows for more frequent stop/start events, reduces battery power consumption, decreases NVH issues, and enhances overall fuel efficiency by lowering the torque needed for engine restarts, thus improving customer satisfaction and reducing emissions.
Implementation Method 1
adjusting the compression release hydraulic valve actuator to open the valve during a compression stroke of the first cylinder
Data Source
AI summary
Methods and systems are provided for providing compression release during a stop/start event in an engine. In one example, a method includes: responsive to a request for a stop/start event in an engine with a continuously variable valve lift (CVVL) system including a compression release hydraulic valve actuator coupled to a valve of a first cylinder, determining a desired stop position of the engine; and prior to restarting the engine during the stop/start event, adjusting the compression release hydraulic valve actuator to open the valve during a compression stroke of the first cylinder. In this way, an amount of torque used to restart the engine may be reduced.