Actuator Control for Partial EGR Valve Oscillation
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Solution Overview
Problem
Internal combustion engines, particularly diesel engines with air intake flaps, experience oscillations in valve or flap actuators during low-flow air regulation, leading to jerks and noise due to the two-stage cascade control system's inability to maintain the required instantaneous setpoint, causing damage and discomfort to the driver.
Innovation Solution
A method and system for controlling the actuator of a partial exhaust gas recirculation valve by comparing the flow measurement with a setpoint, interrupting regulation when the difference exceeds a threshold, and resuming it when the deviation is within a second threshold, allowing controlled valve closing with a varying speed to prevent damage and oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-stage cascade control system is used to regulate valve opening, then the valve is protected from damage by limiting closing speed, but oscillations occur during low-flow regulation causing jerks and noise
Solution Approach 1:
The patent extracts the problematic second regulation stage that causes oscillations and separates its function. When the actuator is within a predefined distance from the stop, the second stage is deactivated, allowing the first stage to directly control the actuator position without the speed-limiting intervention that causes oscillations. This resolves the contradiction by removing the source of harmful oscillations while maintaining valve protection through controlled closing sequences.
Solution Approach 2:
The patent dynamically adjusts the control strategy based on the actuator's position relative to the stop. The switching between direct position control (first stage) and speed-limited control (second stage) is dynamically determined by the distance to the stop. This dynamic approach allows the system to achieve both precise position control and valve protection without the oscillations caused by static speed limitations.
2Reliability
If the second regulation stage limits actuator closing speed to prevent damage, then valve protection is improved, but the actuator cannot reach the required position setpoint instantaneously
Solution Approach 1:
The patent segments the control process into two distinct phases: a first stage for normal position control where the actuator responds quickly to position setpoints, and a second stage for protected closing near the stop where speed is limited. This segmentation allows the actuator to maintain high response speed during most of the travel while only applying speed limitations during the final approach to the stop, thus resolving the contradiction between speed and protection.
Solution Approach 2:
The first regulation stage performs preliminary positioning of the actuator to near the target position before the second stage activates for the final controlled approach. This preliminary action allows the majority of the movement to occur at full speed, with only the final portion requiring speed limitation, thereby maintaining overall response speed while ensuring protected closing.
3Productivity
If the first regulation stage forces the actuator to open to achieve flow setpoint, then flow regulation is improved, but the second stage repeatedly limits speed causing oscillating behavior
Solution Approach 1:
The patent introduces an intermediary switching mechanism that determines when to apply the second regulation stage based on the actuator's distance from the stop. This intermediary logic prevents the conflicting actions of the first and second stages from occurring simultaneously, thereby eliminating the oscillations caused by their interaction while maintaining the flow regulation accuracy provided by the first stage.
Solution Approach 2:
The patent applies the speed-limiting second regulation stage only partially, specifically only when the actuator is within a predefined distance from the stop. This partial application avoids the excessive speed limitation that would occur if the second stage were always active, thereby preventing oscillations while maintaining flow regulation accuracy during the majority of the actuator's range of motion.
Data Source
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AI summary
Method and system for controlling the actuator of a small-opening and regulated-delivery valve. System for controlling the actuator of a partial exhaust gas recirculation valve (16) in an internal combustion engine (10) for a motor vehicle equipped with at least one means (12) of measuring the flowrate of air admitted and with at least one circuit (15) for partial exhaust gas recirculation and controlled by a means (17) of controlling the admitted gases which is able to determine an admitted-air setpoint value, . the control system comprising a means of comparing the flowrate measurement against a flowrate setpoint value (19) able to emit a setpoint value for the position of the actuator which is regulated by an actuator control means (22) capable of preventing damage to the valve, . a means (23) of determining a break in regulation, a means (24) of determining resumed regulation, which means are connected to a regulation control means (25) able to stop regulation and close the valve at a velocity profile that protects the valve from damage when the position of the valve reaches a predefined threshold position indicating that it is near its end stops.