Electrohydraulic Variable Valve Actuator Bypass Control
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Solution Overview
Problem
Current electrohydraulic and electromechanical actuators for engine valve control face challenges such as high energy consumption, difficulty in controlling lift, and limited ability to handle high and varying cylinder air pressure, particularly at high engine speeds, due to inefficiencies in energy transfer and frictional losses, and lack of effective means to adjust valve lift and lash.
Innovation Solution
An electrohydraulic actuator system with a bypass mechanism that short-circuits fluid spaces during certain strokes, using differential pressure forces to assist the spring-mass system, and incorporating snubbing mechanisms to manage friction and energy transfer, allowing for efficient valve control with reduced energy consumption and improved lift adjustment capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If electrohydraulic actuators are used to control engine valves at high speeds, then valve timing control is improved, but energy consumption increases due to frictional losses and inefficient energy transfer
Solution Approach 1:
The patent converts the harmful frictional losses and energy dissipation into beneficial effects by using a bypass mechanism that allows controlled energy dissipation during valve transitions. The bypass valve enables the system to manage energy losses efficiently during high-speed operation, transforming what would be pure waste into a controllable energy management strategy that supports high-speed valve actuation.
Solution Approach 2:
The system dynamically changes operational parameters by adjusting the bypass valve position and hydraulic pressure levels based on engine speed and valve position. This parameter adjustment optimizes energy transfer efficiency at different operating conditions, allowing the actuator to maintain high-speed performance while minimizing energy consumption through adaptive control.
2Ease of operation
If conventional electrohydraulic systems are used, then valve timing control is achieved, but ability to control valve lift is limited
Solution Approach 1:
The patent implements a universal control system where the same electrohydraulic actuator mechanism performs both valve timing control and valve lift control functions. The bypass mechanism and hydraulic system are designed to provide versatile control capabilities, allowing the system to adjust both when the valve opens/closes and how far it travels, eliminating the need for separate control systems.
Solution Approach 2:
The system dynamically adjusts valve lift by controlling the duration and pressure of hydraulic fluid delivery to the actuator. By varying the timing and magnitude of hydraulic pressure application, the system can achieve different lift amounts, transforming a static timing-control-only system into a dynamic system capable of both timing and lift control.
3Stress or pressure
If electrohydraulic actuators operate under high cylinder air pressure, then engine performance is maintained, but frictional losses increase reducing efficiency
Solution Approach 1:
The bypass mechanism converts the harmful effect of high cylinder pressure resistance into a manageable parameter by providing an alternative hydraulic flow path. This allows the system to overcome high cylinder pressure during valve opening while controlling energy dissipation during valve closing, transforming the challenge of high-pressure operation into an efficient energy management opportunity.
4Loss of energy
If bypass mechanism is added to reduce energy losses, then energy efficiency is improved, but device complexity increases
Solution Approach 1:
The patent merges the bypass mechanism with the existing electrohydraulic actuator components, integrating the energy efficiency function into the current system architecture rather than adding a completely separate mechanism. The bypass valve and associated components are incorporated into the existing hydraulic circuitry, reducing overall system complexity compared to adding entirely new subsystems.
Data Source
AI summary
Actuators, and corresponding methods and systems for controlling such actuators, provide independent lift and timing control with minimum energy consumption, while supplying sufficient supplemental energy to overcome friction. In an exemplary embodiment, an actuation cylinder in a housing defines a longitudinal axis and having first and second ends in first and second directions. An actuation piston in the cylinder, with first and second surfaces, is moveable along the longitudinal axis. First and second actuation springs bias the actuation piston in the first and second directions, respectively. A first fluid space is defined by the first end of the actuation cylinder and the first surface of the actuation piston, and a second fluid space is defined by the second end of the actuation cylinder and the second surface of the actuation piston. A fluid bypass short-circuits the first and second fluid spaces when the actuation piston is not substantially proximate to either the first or second end of the actuation cylinder. A first flow mechanism is provided in fluid communication between the first fluid space and a first port, and a second flow mechanism is provided in fluid communication between the second fluid space and a second port. The term "fluid" includes both liquids and gases, and the actuator may be coupled to a stem to form a variable valve actuator in an internal combustion engine, for example.