Electro-Hydraulic Variable Valve Lift Fluid Retention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional variable valve lift systems with hydraulic or electro-hydraulic actuation face issues with hydraulic fluid drainage during extended engine non-use, leading to prolonged repletion times upon engine restart, which is undesirable for vehicle drivers.
Innovation Solution
An electro-hydraulic actuator system with a medium pressure chamber, high pressure oil circuit, control valve, and pump is positioned in the cylinder head assembly to retain hydraulic fluid, ensuring fluid communication and retention during engine shutdown, utilizing an inclined actuator passage and vertically extending stacked-pipe portion to prevent fluid drainage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If hydraulic fluid is allowed to drain during engine shutdown, then the system simplifies fluid management, but the engine restart time increases due to fluid replenishment requirements
Solution Approach 1:
The system performs preliminary action by positioning the medium pressure chamber, control valve, and actuator in an elevated location within the cylinder head assembly before engine shutdown occurs. This elevation creates a gravity-based fluid retention mechanism that prevents hydraulic fluid from draining out during extended engine non-use, ensuring immediate availability of fluid for engine restart without requiring complex active retention systems
Solution Approach 2:
The elevated medium pressure chamber acts as an intermediary reservoir positioned between the hydraulic fluid source and the actuator components. By placing this chamber above the control valve and actuator, the system creates a gravity-fed fluid supply path that maintains fluid presence in critical components during shutdown, mediating between the need for fluid retention and system simplicity
2Reliability
If the actuator passage is inclined upward from control valve to actuator, then hydraulic fluid is retained during engine shutdown, but the manufacturing complexity increases
Solution Approach 1:
The actuator passage is designed with asymmetric inclination, sloping upward from the control valve location toward the actuator location. This asymmetric geometry exploits gravity to retain hydraulic fluid in the passage and components during engine shutdown. The inclined design, while adding some manufacturing complexity, provides reliable passive fluid retention without requiring additional active retention mechanisms
3Quantity of substance
If the medium pressure chamber is positioned higher than the control valve, then hydraulic fluid remains in the chamber during shutdown, but the vertical space requirement increases
Solution Approach 1:
The medium pressure chamber is positioned at a higher vertical elevation within the cylinder head assembly, utilizing the vertical dimension to create gravity-based fluid retention. By arranging components in a vertical hierarchy (chamber above valve above actuator), the system retains hydraulic fluid in critical components during shutdown. This vertical arrangement, while requiring additional height, provides effective passive fluid retention without complex mechanisms
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
The system effectively retains hydraulic fluid in the actuation components, minimizing the delay in engine valve actuation and startup time upon extended engine non-use by maintaining a supply of hydraulic fluid, thus enhancing operational efficiency and user convenience.
Implementation Method 1
The pump is configured to pump hydraulic fluid in the high pressure oil circuit
Implementation Method 2
The control valve is configured to be controlled to selectively block fluid communication between the high pressure oil circuit and the medium pressure chamber
Implementation Method 3
The medium pressure chamber and the actuator are each positioned in the cylinder head assembly at a location higher than the control valve such that during an engine shutdown event, hydraulic fluid is retained in the medium pressure chamber and the control valve
Implementation Method 4
the actuator passage is inclined such that the hydraulic fluid flows upwardly in the actuation passage from the valve end toward the actuator end when the engine is in a level operating position
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An electro-hydraulic variable valve lift system includes a medium pressure chamber, a high pressure circuit, a valve, a pump and an actuator. The chamber is formed in a cylinder head assembly and is in fluid communication with a hydraulic fluid source. The high pressure circuit is positioned in the cylinder head assembly and is in selective fluid communication with the chamber. The valve is in fluid communication with the chamber and the high pressure circuit, and the pump is configured to pump hydraulic fluid in the high pressure circuit. The actuator is in fluid communication with the pump, control valve and high pressure circuit, and is in engagement with an intake valve. The chamber and the actuator are each positioned in the cylinder head assembly at a location above the valve such that during an engine shutdown event, hydraulic fluid is retained in the chamber and the valve.