Variable Valve Gear Control for Pre-ignition Prevention
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Solution Overview
Problem
Internal combustion engines with variable valve mechanisms face challenges in preventing pre-ignition, which can lead to increased vibration and noise, especially when operating at high temperatures, and existing solutions either reduce engine output or cause vibration and noise issues when modifying valve timing.
Innovation Solution
A control device and method that continuously varies the intake valve's closing timing and operating angle, detects pre-ignition conditions, and adjusts the throttle opening to prevent pre-ignition, while setting upper limits for the intake valve operating angle and throttle opening to manage noise and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the valve timing is modified to reduce the actual compression ratio to prevent pre-ignition, then pre-ignition is prevented, but vibration or noise occurs in a vehicle
Solution Approach 1:
The invention changes the operating angle parameter of the intake valve to prevent pre-ignition while controlling vibration and noise. By increasing the operating angle upper limit when pre-ignition is detected, the valve timing is modified to reduce compression ratio without causing excessive vibration or noise, thus resolving the contradiction between pre-ignition prevention and vibration/noise control.
2Reliability
If the intake air amount is limited to prevent pre-ignition, then pre-ignition is prevented, but a reduction in engine output torque occurs
Solution Approach 1:
Instead of limiting intake air amount, the invention changes the operating angle parameter of the intake valve to prevent pre-ignition. By adjusting the operating angle upper limit, the system prevents pre-ignition through valve timing modification while maintaining normal intake air flow, thus avoiding the loss of engine output torque.
3Reliability
If the intake valve operating angle is increased to prevent pre-ignition, then pre-ignition is prevented, but the upper limit of operating angle must be controlled to suppress noise and vibration
Solution Approach 1:
The invention dynamically adjusts the operating angle upper limit based on detected pre-ignition conditions and noise/vibration requirements. The control device modifies the operating angle limit in real-time, allowing increased operating angle when pre-ignition prevention is needed while suppressing noise and vibration by enforcing upper limits under normal conditions.
Solution Approach 2:
The system changes the operating angle parameter dynamically based on operating conditions. When pre-ignition is detected, the operating angle upper limit is increased to prevent pre-ignition, while under normal conditions, the operating angle is kept within limits that suppress noise and vibration, thus resolving the contradiction between pre-ignition prevention and noise/vibration control.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
In a control device 13 for an internal combustion engine includes an intake valve, a variable valve mechanism 9 capable of controlling a closing timing and an operating angle of an intake valve 7 continuously and variably, a detection unit B60 for detecting a possibility of pre-ignition, and a throttle 15 for controlling an intake air amount such that when the possibility of pre-ignition is detected, the intake valve closing timing is retarded from bottom dead center by increasing the intake valve operating angle, the control device 13 includes, an operating angle upper limit limiting value calculation unit B55 that calculates an operating angle upper limit limiting value for limiting an upper limit value of the intake valve operating angle, and a throttle opening upper limit limiting value calculation unit B61 that calculates a throttle opening upper limit limiting value for limiting an upper limit value of a throttle opening on the basis of the intake valve operating angle.